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Mouloud Kecha

University Abderahmane Mira, Bejaia, Microbiology, Faculty Member

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Mouloud KECHA spent two years during his doctoral research in Reims University (France)

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University of Washington

Massachusetts Institute of Technology (MIT)

Sergei Shchebetenko

National Research University “Higher School of Economics” (HSE), Moscow, Russia

Snezana Zhana Vrangalova

New York University

Friederike Moltmann

Centre National de la Recherche Scientifique / French National Centre for Scientific Research

University of Belgrade

José Ignacio Pichardo Galán

Universidad Complutense de Madrid

University of Massachusetts Amherst

Bar-Ilan University

Róża Bazińska

Szkoła Wyższa Psychologii Społecznej

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Papers by Mouloud Kecha

Isolement et sélection de souches d’actinomycètes productrices d’antibiotiques « Essai d’identification phénotypique et chimiotaxonomique »

AMWEst, a new thermostable and detergent-tolerant esterase retrieved from the Albian aquifer

Applied Microbiology and Biotechnology, Jan 9, 2024

A fosmid library was constructed with the metagenomic DNA from the high-temperature sediment-rich... more A fosmid library was constructed with the metagenomic DNA from the high-temperature sediment-rich water of the Albian aquifer (Algeria). Functional screening of this library was subsequently done looking for genes encoding lipolytic enzymes. We identified a novel gene named AMWEst (1209 base pairs) encoding a protein of 402 amino acids with a predicted molecular weight of 43.44 kDa and conferring esterase activity. AMWEst was successfully overexpressed in the yeast mesophilic host Saccharomyces cerevisiae, and the expression system used proved to be efficient and produced sufficient activity for its biochemical characterization. Multiple sequence alignment indicated that AMWEst contained a conserved pentapeptide motif (Gly120-His121-Ser122-Gln123-Gly124). The optimum pH and temperature of the recombinant esterase AMWEst were 8 and 80 °C, respectively. Additionally, AMWEst showed higher activity towards short carbon substrates and showed maximum activity for p-nitrophenyl hexanoate (C6). Notably, AMWEst has a remarkable thermostability, and the enzyme retains almost maximum activity at 70 °C after incubation for 1 h. Moreover, enzyme activity was enhanced by high concentrations of SDS and Triton X-100 detergents.

Characterization and optimization of extracellular L-Asparaginase production by selected Actinomycete strain isolated from an algerian wheat bran

Cellular and Molecular Biology, Nov 30, 2018

L-Asparaginase is an enzyme that hydrolyses the amino acid L-Asparagine into aspartic acid and am... more L-Asparaginase is an enzyme that hydrolyses the amino acid L-Asparagine into aspartic acid and ammonia. As a medication, L-Asparaginase is used in chemotherapy to treat acute lymphoblastic leukaemia by depleting circulating Asparagine and depriving tumor cells. Interest in Actinomycetes as potential producers of antibiotics and enzymes encouraged us to investigate an isolated strain (CA01) from soft wheat bran.The Actinomycete strain was characterized based on its morphological and biochemical characteristics and selected due to a proved promising ability to produce L-Asparaginase optimized in both solid and liquid media cultures.The conditions of enzyme production were standardized according to a one-factor-at-a-time (OFAT) experimental design.To obtain optimal medium combination, a Box-Behnken Response Surface Methodology (RSM) has been adopted by choosing the most influential factors. The optimal conditions for the enzyme production were (g/l): L-Asparagine 10.7; Glucose 2.7; starch 7, in based medium containing (g/l): K 2 HPO 4 0.5; MgSO 4 , 7H 2 O 0.1, corresponding to an optimal enzymatic activity of 8.03 IU/ml at 27.83°C. The maximum production of enzyme was reached on the sixth day of experiment. The ANOVA test (P value ˂ 0.05) and adjusted R 2 values close to the experimental R 2 show that the obtained model of the active L-Asparaginase of CA01 strain production is significant with the following linear terms: temperature, substrate concentration, Glucose concentration and there squared.

Caractérisation culturale, biochimique et physiologique d’une souche Streptomyces sp. productrice d’antibiotiques

Activité antagoniste de deux souches de Streptomyces à l’égard d’une nouvelle collection

Activité antagoniste de deux souches de Streptomyces à l'égard d'une nouvelle collection de bacté... more

Integrated metabolomic, molecular networking, and genome mining analyses uncover novel angucyclines from <i>Streptomyces</i> sp. RO-S4 strain isolated from Bejaia Bay, Algeria

bioRxiv (Cold Spring Harbor Laboratory), Dec 21, 2021

Multi-omic approaches have recently made big strides toward the effective exploration of microorg... more Multi-omic approaches have recently made big strides toward the effective exploration of microorganisms, accelerating the discovery of new bioactive compounds. We combined metabolomic, molecular networking, and genomic-based approaches to investigate the metabolic potential of the Streptomyces sp. RO-S4 strain isolated from the polluted waters of Bejaia Bay in Algeria. Antagonistic assays against methicillin-resistant Staphylococcus aureus with RO-S4 organic extracts showed an inhibition zone of 20 mm by using the agar diffusion method, and its minimum inhibitory concentration was 16 µg/ml. A molecular network was created using GNPS and annotated through the comparison of MS/MS spectra against several databases. The predominant compounds in the RO-S4 extract belonged to the angucycline family. Three compounds were annotated as known metabolites, while all the others were putatively new to Science. Notably, all compounds had fridamycin-like aglycones, and several of them had a lactonized D ring analogous to that of urdamycin L. The whole genome of Streptomyces RO-S4 was sequenced to identify the biosynthetic gene cluster (BGC) linked to these angucyclines, which yielded a draft genome of 7,497,846 bp with 72.4% G+C content. Subsequently, a genome mining analysis revealed 19 putative biosynthetic gene clusters, including a grincamycin-like BGC with high similarity to that of Streptomyces sp. CZN-748, that was previously reported to also produce mostly open fridamycin-like aglycones. As the ring-opening process leading to these compounds is still not defined, we performed a comparative analysis with other angucycline BGCs and advanced some hypotheses to explain the ring-opening and lactonization, possibly linked to the uncoupling between the activity of GcnE and GcnM homologs in the RO-S4 strain. The combination of metabolomic and genomic approaches greatly improved the interpretation of the metabolic potential of the RO-S4 strain.

Epidemiological investigation of subclinical bovine mastitis in Algeria and molecular characterization of biofilm-forming Staphylococcus aureus

Tropical Animal Health and Production, Jul 23, 2019

Thirty dairy farms were selected for this study; the first objective of our study was to investig... more Thirty dairy farms were selected for this study; the first objective of our study was to investigate the prevalence of subclinical bovine mastitis (SCM) in Eastern Algeria, from 600 lactating cows, and to identify potential risk factors associated with the occurrence of bovine mastitis and bacteria isolation using logistic regression. The second objective was to evaluate biofilm formation capacity and detect biofilm-associated genes of S. aureus, isolated from SCM cases. Molecular typing was investigated by spa typing. The prevalence of mastitis at cow and quarter level was 37.66% (226/600) and 27.17% (555/2042), respectively. Stage of lactation, cow breed, milk production, and the study area were factors associated with SCM. In addition, the most frequent pathogens isolated from mastitic milk were coagulase-negative staphylococci (CNS), E. coli, and S. aureus. The study area was highly associated with SCM caused by S. aureus; cows from Setif province were 18 times more affected with SCM caused by S. aureus compared to cows from Batna province (OR = 18.6, 95%CI 2.038–171.2), but were less affected with SCM caused by CNS isolates (OR = 0.17, 95%CI 0.033–0.868). Moreover, cows with milk production less than 10 L per day increased (p < 0.05) the prevalence of mastitis caused by E. coli. All the S. aureus isolates had biofilm-forming ability, and 41.66% of isolates were positive for adhesion genes (icaA, icaD, fbnA, and clfA). This study, therefore, warrants the need for improving sanitary measures and strict hygienic measures, and presents the first insight into biofilm-forming ability of S. aureus strains causing mastitis in dairy herds in Algeria, which will help in tracking the evolution of epidemic strains responsible for causing bovine mastitis.

Interaction of primary mammary bovine epithelial cells with biofilm-forming staphylococci associated with subclinical bovine mastitis

PubMed, 2019

Background: Staphylococci are recognized worldwide as one of the most important etiological agent... more Background: Staphylococci are recognized worldwide as one of the most important etiological agents of bovine mastitis due to their virulence factors such as their ability to penetrate inside mammary epithelial cells and their ability to form biofilm. Aims: The objectives of this study were to establish a model of primary mammary epithelial cells originating from the secretory tissue of the bovine udder in order to evaluate the invasion ability of 42 staphylococci isolated from subclinical bovine mastitis cases. Methods: Two techniques were used to establish a model of primary mammary epithelial cells, the explant technique and the enzymatic method. Biofilm formation was detected using a quantitative spectrophotometric assay. When compared with the enzymatic digestion method, the epithelial cells obtained by the explant technique grew faster and reached quickly to confluence. Results: The results showed that 60% of Staphylococcus aureus isolates (n=12) were able to invade the epithelial cells and 72.7% of coagulase negative staphylococci (CNS) isolates were invasive (n=16). Staphylococcus xylosus isolates showed higher invasion values compared to S. aureus isolates and non-biofilm forming staphylococci were able to invade primary epithelial cells, but no significant difference was found between the internalization capabilities of biofilm positive and negative isolates. Conclusion: The results show that the explant technique is a valuable method for developing primary epithelial cells without damaging the cells, and provides new insights regarding the ability of staphylococci to penetrate inside primary mammary epithelial cells.

Identification of staphylococci causing mastitis in dairy cattle from Algeria and characterization of<i>Staphylococcus aureus</i>

Journal of Applied Microbiology, Aug 9, 2019

Staphylococcus aureus isolates. Methods and Results: Quarter milk samples were collected separate... more Staphylococcus aureus isolates. Methods and Results: Quarter milk samples were collected separately, somatic cells were counted and samples with more than 200 000 somatic cells/mL were cultured on blood agar. Staphylococci isolates were identified by routine diagnostics, and S. aureus isolates were tested for antibiotic susceptibility by disk diffusion and microdilution. Congo red agar was used to detect biofilm formation and capsule synthesis was detected on serum soft agar (SSA). The S. aureus isolates were characterized by spa typing. DNA microarray analysis was performed to detect resistance and virulence genes. Overall, 40.0% (167/418) of the cows suffered from mastitis. In 63.5% (106/167) of them staphylococci were identified. Nine of the 106 Staphylococcus isolates (8.5%) were S. aureus. The coagulase-negative staphylococci (CoNS) belonged to 14 species. All S. aureus isolates were multiresistant and biofilm forming, 66.67% of them showed diffuse colonies on SSA and belonged to CC97-agrI-cap5. Biofilm genes (icaA/C/D), 13 genes encoding for adhesion, six genes encoding proteases, 11 genes encoding super-antigen like toxins were found. Genes conferring resistance to tetracycline [tet(K)], penicillin (blaZ/I/R), and macrolide-lincosamidestreptogramin B [erm(B), erm(A)] were also detected in the S. aureus from this study. Conclusions: The current investigation provides a detailed molecular and biofilm formation ability of S. aureus involved in subclinical mastitis in Algeria and shows the wide distribution Accepted Article This article is protected by copyright. All rights reserved. of adhesion and enterotoxin(-like) genes among S. aureus responsible for causing subclinical bovine mastitis.

5th World Conference on Applied Microbiology and Beneficial Microbes Awards 2020

Research and Reviews: Journal of Microbiology and Biotechnology, 2020

Antifungal Molecules Produced by a New Salt-Tolerant and Alkaliphilic Streptomyces sp. BS30 Isolated from an Arid Soil

Proceedings of the National Academy of Sciences, India, Section B: biological sciences, Aug 11, 2015

A salt-tolerant and alkaliphilic actinomycete BS30 isolated from a Saharan soil sample of Algeria... more A salt-tolerant and alkaliphilic actinomycete BS30 isolated from a Saharan soil sample of Algeria, exhibited optimum growth at 2 % (w/v) NaCl and pH10. The strain exhibited antimicrobial activity against yeast and toxinogenic fungi. Analysis of the 16S rRNA gene sequence (1476 nucleotides) of the BS30 strain showed 98.77 % similarity with 16S rRNA gene sequence of Streptomyces spiroverticillatus NBRC 12821 T , the most closely related type species. The phylogenetic analysis indicated that the BS30 strain represent a distinct phyletic line suggesting a potential new genomic species. Two bioactive molecules were isolated from the culture broth using various separation and purification steps. The first partially purified bioactive product was subjected to gas chromatography-mass spectrometry (GC-MS). The second fraction was analyzed by ultraviolet-visible (UV-VIS) spectrometry, electro-spray ionization mass (ESI-MS) and high resolution mass spectrometry (HR-ESI-MS) coupled with analytical liquid chromatography (HPLC) with a diode array detector (DAD). The two compounds showed significant antifungal activity against Aspergillus niger 2CA936.

Screening of Fungal Strains Isolated from Algerian Soil for the Production of Extracellular Enzymes

Natural Resources and Sustainable Development, 2022

Optimization of antifungal production by an alkaliphilic and halotolerant actinomycete, Streptomyces sp. SY-BS5, using response surface methodology

Journal De Mycologie Medicale, Jun 1, 2015

Optimization of medium components and physicochemical parameters for antifungal production by an ... more Optimization of medium components and physicochemical parameters for antifungal production by an alkaliphilic and salt-tolerant actinomycete designated Streptomyces sp. SY-BS5; isolated from an arid region in south of Algeria. The strain showed broad-spectrum activity against pathogenic and toxinogenic fungi. Identification of the actinomycete strain was realized on the basis of 16S rRNA gene sequencing. Antifungal production was optimized following one-factor-at-a-time (OFAT) and response surface methodology (RSM) approaches. The most suitable medium for growth and antifungal production was found using one-factor-at-a-time methodology. The individual and interaction effects of three nutritional variables, carbon source (glucose), nitrogen source (yeast extract) and sodium chloride (NaCl) were optimized by Box-Behnken design. Finally, culture conditions for the antifungal production, pH and temperature were studied and determined. Analysis of the 16S rRNA gene sequence (1454 nucleotides) assigned this strain to Streptomyces genus with 99% similarity with Streptomyces cyaneofuscatus JCM4364(T), the most closely related. The results of the optimization study show that concentrations 3.476g/L of glucose, 3.876g/L of yeast extract and 41.140g/L of NaCl are responsible for the enhancement of antifungal production by Streptomyces sp. SY-BS5. The preferable culture conditions for antifungal production were pH 10, temperature 30°C for 09 days. This study proved that RSM is usual and powerful tool for the optimization of antifungal production from actinomycetes.

Extraction et purification de l’exo-p-(i-3)-glucanase du suc digestif d’escargot (Helix pomatia)

Extraction et purification de l'exo-P-(1-3)-glucanase du suc digestif d'escargot (Helix pomatia). Étude de la protoplastisation sur Saccharomyces cerevisiae

L'extraction et la purification de la β-(1,3)-glucanase du suc d'Helix pomatia par precip... more L'extraction et la purification de la β-(1,3)-glucanase du suc d'Helix pomatia par precipitation au sulfate d'ammonium 25, 40, 60 et 80% montre que la fraction 40% presente une meilleure activite specifique 17U/mg avec un rendement de 24,40%, L'elution chromatographique de la fraction -40% indique que les eluats compris entre les tubes 25 et 31 constituent un seul pic avec un maximum d'activite specifique a 104 U/mg. Ces eluats rassembles forme la fraction dite '25-31' avec une activite specifique de 161 U/mg et un rendement de 2%. L'etude comparative de la protoplastisation de la levure Saccharomyces cerevisiae avec la cytohelicase commerciale et la preparation enzymatique obtenue a ete realisee avec et sans pretraitement au mercapto-ethanol. Les rendements sans pretraitement s'averent dans les deux cas trop faibles, par contre les rendements obtenus avec un pretraitement sont de 83 et 80% respectivement avec la cytohelicase commerciale et l'extrait enzymatique. Par ailleurs, les taux de protoplastisation pourraient etre ameliores en utilisant des cellules en phase de croissance de 15 heures de culture et avec une concentration d'enzyme egale a 0,022mg/ml.

Etude Des Phenotypes De Resistance Aux -Lactamines Des Souches D’Enterobacteries Isolees en Milieu Hospitalier : Cas De L’Hopital D’Amizour (W. Bejaia)

Sciences & Technologie, Jun 1, 2003

Taxonomy and Study of Antimicrobial Activity of Two HalophilicActinomycetes AH1 and AH2 Isolated from a Saline Soil of Bejaia(Algeria)

Research and reviews in biosciences, 2012

In this study we are interested in the taxonomic characterization of two isolates of halophilic a... more In this study we are interested in the taxonomic characterization of two isolates of halophilic actinomycetes, the identification of their antimicrobial and antifungal activities, and the determination of the chemical nature of bioactive molecules. Both strains AH1 and AH2 were isolated from saline soil in the region of Bejaia (Algeria). Based on morphological and chemotaxonomic characteristics, these isolates AH1 and AH2 are related to the genus Streptomyces. The growth and the antibiotic production by the two isolates are evaluated on two liquid culture media (ISP2 and M2) at different concentrations of NaCl. The results obtained showed that the antibiotic activity (antibacterial and antifungal) is very important. Extraction of antibiotic from Crude extracts by dichloromethane and n-butanol from the culture filtrate of the isolate AH1 and AH2 respectively, showed good activities, also, the crude extracts with hexane for both isolates showed a very important antifungal activity. The antibiotic complexes were located by bioautgraphy, and suggest that these molecules belong to subfamilies of aminoglycosides and polyether, and these antibiotics are non-polyenic.

Physiology and growth of Pyrococcus sp. HT3 in bach culture with cellobiose and maltose as the principal carbon sources

BioTechnology: An Indian Journal, 2012

The hydrothermal hot spring archaeonPyrococcussp. T3 was grown in batch cultures in closed bottle... more The hydrothermal hot spring archaeonPyrococcussp. T3 was grown in batch cultures in closed bottles, both in the presence and in the absence of elemental sulfur. Growth on carbohydrates, proteinaceous substrates and amino acids was investigated. The disaccharides maltose and cellobiose were shown not to be able to enhance growth suggesting that Pyrococcussp. T3 is unable to use them as sole carbon sources. By contrast, proteinaceous substrates such as peptone and brain heart infusion were shown to be very good substrates for the growth of Pyrococcussp. T3. Growth on brain heart infusion was shown to require additional nutrients when sulfur was not present in the culture medium. Growth on amino acids only took place in the presence of sulfur. These results indicate that sulfur plays an important role in the metabolism and energetics of Pyrococcussp. HT3.

Statistical Medium Optimization for the Production of Anti-Methicillin-Resistant Staphylococcus aureus Metabolites from a Coal-Mining-Soil-Derived Streptomyces rochei CMB47

Fermentation, Apr 15, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more

Characterization of a Haloalkaline Nocardiopsis sp. Strain S10 Isolated from Wastewater and Optimization of Culture Medium for Improving Production of Antifungal Compounds

Anti-Infective Agents

Background: The emerging antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG... more Background: The emerging antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are a pressing global concern. Furthermore, the limited number of available antifungal agents requires the discovery of new antimicrobials. Introduction: This paper focused on the isolation and characterization of an actinobacterium designated S10, the study of its antimicrobial activity, on the one hand, and the optimization of antifungal production using statistical methods, on the other hand. Methods and Results: A haloalkaliphilic actinobacterium designated S10 was isolated from a wastewater treatment plant in the Souk-El-Tenine region (Bejaia, Algeria). This strain showed a broad spectrum of activity against bacteria (B. subtilis, L. innocua, M. luteus, S. aureus, MRSA, E. coli, P. aeruginosa, S. Typhi, and V. cholerae), molds (A. niger, G. geotricum, and F. oxysporum) and a pathogenic yeast (C. albicans). The extracellular enzymes producer Nocardiopsis sp. S10 was identified bas...

Isolement et sélection de souches d’actinomycètes productrices d’antibiotiques « Essai d’identification phénotypique et chimiotaxonomique »

AMWEst, a new thermostable and detergent-tolerant esterase retrieved from the Albian aquifer

Applied Microbiology and Biotechnology, Jan 9, 2024

A fosmid library was constructed with the metagenomic DNA from the high-temperature sediment-rich... more A fosmid library was constructed with the metagenomic DNA from the high-temperature sediment-rich water of the Albian aquifer (Algeria). Functional screening of this library was subsequently done looking for genes encoding lipolytic enzymes. We identified a novel gene named AMWEst (1209 base pairs) encoding a protein of 402 amino acids with a predicted molecular weight of 43.44 kDa and conferring esterase activity. AMWEst was successfully overexpressed in the yeast mesophilic host Saccharomyces cerevisiae, and the expression system used proved to be efficient and produced sufficient activity for its biochemical characterization. Multiple sequence alignment indicated that AMWEst contained a conserved pentapeptide motif (Gly120-His121-Ser122-Gln123-Gly124). The optimum pH and temperature of the recombinant esterase AMWEst were 8 and 80 °C, respectively. Additionally, AMWEst showed higher activity towards short carbon substrates and showed maximum activity for p-nitrophenyl hexanoate (C6). Notably, AMWEst has a remarkable thermostability, and the enzyme retains almost maximum activity at 70 °C after incubation for 1 h. Moreover, enzyme activity was enhanced by high concentrations of SDS and Triton X-100 detergents.

Characterization and optimization of extracellular L-Asparaginase production by selected Actinomycete strain isolated from an algerian wheat bran

Cellular and Molecular Biology, Nov 30, 2018

L-Asparaginase is an enzyme that hydrolyses the amino acid L-Asparagine into aspartic acid and am... more L-Asparaginase is an enzyme that hydrolyses the amino acid L-Asparagine into aspartic acid and ammonia. As a medication, L-Asparaginase is used in chemotherapy to treat acute lymphoblastic leukaemia by depleting circulating Asparagine and depriving tumor cells. Interest in Actinomycetes as potential producers of antibiotics and enzymes encouraged us to investigate an isolated strain (CA01) from soft wheat bran.The Actinomycete strain was characterized based on its morphological and biochemical characteristics and selected due to a proved promising ability to produce L-Asparaginase optimized in both solid and liquid media cultures.The conditions of enzyme production were standardized according to a one-factor-at-a-time (OFAT) experimental design.To obtain optimal medium combination, a Box-Behnken Response Surface Methodology (RSM) has been adopted by choosing the most influential factors. The optimal conditions for the enzyme production were (g/l): L-Asparagine 10.7; Glucose 2.7; starch 7, in based medium containing (g/l): K 2 HPO 4 0.5; MgSO 4 , 7H 2 O 0.1, corresponding to an optimal enzymatic activity of 8.03 IU/ml at 27.83°C. The maximum production of enzyme was reached on the sixth day of experiment. The ANOVA test (P value ˂ 0.05) and adjusted R 2 values close to the experimental R 2 show that the obtained model of the active L-Asparaginase of CA01 strain production is significant with the following linear terms: temperature, substrate concentration, Glucose concentration and there squared.

Caractérisation culturale, biochimique et physiologique d’une souche Streptomyces sp. productrice d’antibiotiques

Activité antagoniste de deux souches de Streptomyces à l’égard d’une nouvelle collection

Activité antagoniste de deux souches de Streptomyces à l'égard d'une nouvelle collection de bacté... more

Integrated metabolomic, molecular networking, and genome mining analyses uncover novel angucyclines from <i>Streptomyces</i> sp. RO-S4 strain isolated from Bejaia Bay, Algeria

bioRxiv (Cold Spring Harbor Laboratory), Dec 21, 2021

Multi-omic approaches have recently made big strides toward the effective exploration of microorg... more Multi-omic approaches have recently made big strides toward the effective exploration of microorganisms, accelerating the discovery of new bioactive compounds. We combined metabolomic, molecular networking, and genomic-based approaches to investigate the metabolic potential of the Streptomyces sp. RO-S4 strain isolated from the polluted waters of Bejaia Bay in Algeria. Antagonistic assays against methicillin-resistant Staphylococcus aureus with RO-S4 organic extracts showed an inhibition zone of 20 mm by using the agar diffusion method, and its minimum inhibitory concentration was 16 µg/ml. A molecular network was created using GNPS and annotated through the comparison of MS/MS spectra against several databases. The predominant compounds in the RO-S4 extract belonged to the angucycline family. Three compounds were annotated as known metabolites, while all the others were putatively new to Science. Notably, all compounds had fridamycin-like aglycones, and several of them had a lactonized D ring analogous to that of urdamycin L. The whole genome of Streptomyces RO-S4 was sequenced to identify the biosynthetic gene cluster (BGC) linked to these angucyclines, which yielded a draft genome of 7,497,846 bp with 72.4% G+C content. Subsequently, a genome mining analysis revealed 19 putative biosynthetic gene clusters, including a grincamycin-like BGC with high similarity to that of Streptomyces sp. CZN-748, that was previously reported to also produce mostly open fridamycin-like aglycones. As the ring-opening process leading to these compounds is still not defined, we performed a comparative analysis with other angucycline BGCs and advanced some hypotheses to explain the ring-opening and lactonization, possibly linked to the uncoupling between the activity of GcnE and GcnM homologs in the RO-S4 strain. The combination of metabolomic and genomic approaches greatly improved the interpretation of the metabolic potential of the RO-S4 strain.

Epidemiological investigation of subclinical bovine mastitis in Algeria and molecular characterization of biofilm-forming Staphylococcus aureus

Tropical Animal Health and Production, Jul 23, 2019

Thirty dairy farms were selected for this study; the first objective of our study was to investig... more Thirty dairy farms were selected for this study; the first objective of our study was to investigate the prevalence of subclinical bovine mastitis (SCM) in Eastern Algeria, from 600 lactating cows, and to identify potential risk factors associated with the occurrence of bovine mastitis and bacteria isolation using logistic regression. The second objective was to evaluate biofilm formation capacity and detect biofilm-associated genes of S. aureus, isolated from SCM cases. Molecular typing was investigated by spa typing. The prevalence of mastitis at cow and quarter level was 37.66% (226/600) and 27.17% (555/2042), respectively. Stage of lactation, cow breed, milk production, and the study area were factors associated with SCM. In addition, the most frequent pathogens isolated from mastitic milk were coagulase-negative staphylococci (CNS), E. coli, and S. aureus. The study area was highly associated with SCM caused by S. aureus; cows from Setif province were 18 times more affected with SCM caused by S. aureus compared to cows from Batna province (OR = 18.6, 95%CI 2.038–171.2), but were less affected with SCM caused by CNS isolates (OR = 0.17, 95%CI 0.033–0.868). Moreover, cows with milk production less than 10 L per day increased (p < 0.05) the prevalence of mastitis caused by E. coli. All the S. aureus isolates had biofilm-forming ability, and 41.66% of isolates were positive for adhesion genes (icaA, icaD, fbnA, and clfA). This study, therefore, warrants the need for improving sanitary measures and strict hygienic measures, and presents the first insight into biofilm-forming ability of S. aureus strains causing mastitis in dairy herds in Algeria, which will help in tracking the evolution of epidemic strains responsible for causing bovine mastitis.

Interaction of primary mammary bovine epithelial cells with biofilm-forming staphylococci associated with subclinical bovine mastitis

PubMed, 2019

Background: Staphylococci are recognized worldwide as one of the most important etiological agent... more Background: Staphylococci are recognized worldwide as one of the most important etiological agents of bovine mastitis due to their virulence factors such as their ability to penetrate inside mammary epithelial cells and their ability to form biofilm. Aims: The objectives of this study were to establish a model of primary mammary epithelial cells originating from the secretory tissue of the bovine udder in order to evaluate the invasion ability of 42 staphylococci isolated from subclinical bovine mastitis cases. Methods: Two techniques were used to establish a model of primary mammary epithelial cells, the explant technique and the enzymatic method. Biofilm formation was detected using a quantitative spectrophotometric assay. When compared with the enzymatic digestion method, the epithelial cells obtained by the explant technique grew faster and reached quickly to confluence. Results: The results showed that 60% of Staphylococcus aureus isolates (n=12) were able to invade the epithelial cells and 72.7% of coagulase negative staphylococci (CNS) isolates were invasive (n=16). Staphylococcus xylosus isolates showed higher invasion values compared to S. aureus isolates and non-biofilm forming staphylococci were able to invade primary epithelial cells, but no significant difference was found between the internalization capabilities of biofilm positive and negative isolates. Conclusion: The results show that the explant technique is a valuable method for developing primary epithelial cells without damaging the cells, and provides new insights regarding the ability of staphylococci to penetrate inside primary mammary epithelial cells.

Identification of staphylococci causing mastitis in dairy cattle from Algeria and characterization of<i>Staphylococcus aureus</i>

Journal of Applied Microbiology, Aug 9, 2019

Staphylococcus aureus isolates. Methods and Results: Quarter milk samples were collected separate... more Staphylococcus aureus isolates. Methods and Results: Quarter milk samples were collected separately, somatic cells were counted and samples with more than 200 000 somatic cells/mL were cultured on blood agar. Staphylococci isolates were identified by routine diagnostics, and S. aureus isolates were tested for antibiotic susceptibility by disk diffusion and microdilution. Congo red agar was used to detect biofilm formation and capsule synthesis was detected on serum soft agar (SSA). The S. aureus isolates were characterized by spa typing. DNA microarray analysis was performed to detect resistance and virulence genes. Overall, 40.0% (167/418) of the cows suffered from mastitis. In 63.5% (106/167) of them staphylococci were identified. Nine of the 106 Staphylococcus isolates (8.5%) were S. aureus. The coagulase-negative staphylococci (CoNS) belonged to 14 species. All S. aureus isolates were multiresistant and biofilm forming, 66.67% of them showed diffuse colonies on SSA and belonged to CC97-agrI-cap5. Biofilm genes (icaA/C/D), 13 genes encoding for adhesion, six genes encoding proteases, 11 genes encoding super-antigen like toxins were found. Genes conferring resistance to tetracycline [tet(K)], penicillin (blaZ/I/R), and macrolide-lincosamidestreptogramin B [erm(B), erm(A)] were also detected in the S. aureus from this study. Conclusions: The current investigation provides a detailed molecular and biofilm formation ability of S. aureus involved in subclinical mastitis in Algeria and shows the wide distribution Accepted Article This article is protected by copyright. All rights reserved. of adhesion and enterotoxin(-like) genes among S. aureus responsible for causing subclinical bovine mastitis.

5th World Conference on Applied Microbiology and Beneficial Microbes Awards 2020

Research and Reviews: Journal of Microbiology and Biotechnology, 2020

Antifungal Molecules Produced by a New Salt-Tolerant and Alkaliphilic Streptomyces sp. BS30 Isolated from an Arid Soil

Proceedings of the National Academy of Sciences, India, Section B: biological sciences, Aug 11, 2015

A salt-tolerant and alkaliphilic actinomycete BS30 isolated from a Saharan soil sample of Algeria... more A salt-tolerant and alkaliphilic actinomycete BS30 isolated from a Saharan soil sample of Algeria, exhibited optimum growth at 2 % (w/v) NaCl and pH10. The strain exhibited antimicrobial activity against yeast and toxinogenic fungi. Analysis of the 16S rRNA gene sequence (1476 nucleotides) of the BS30 strain showed 98.77 % similarity with 16S rRNA gene sequence of Streptomyces spiroverticillatus NBRC 12821 T , the most closely related type species. The phylogenetic analysis indicated that the BS30 strain represent a distinct phyletic line suggesting a potential new genomic species. Two bioactive molecules were isolated from the culture broth using various separation and purification steps. The first partially purified bioactive product was subjected to gas chromatography-mass spectrometry (GC-MS). The second fraction was analyzed by ultraviolet-visible (UV-VIS) spectrometry, electro-spray ionization mass (ESI-MS) and high resolution mass spectrometry (HR-ESI-MS) coupled with analytical liquid chromatography (HPLC) with a diode array detector (DAD). The two compounds showed significant antifungal activity against Aspergillus niger 2CA936.

Screening of Fungal Strains Isolated from Algerian Soil for the Production of Extracellular Enzymes

Natural Resources and Sustainable Development, 2022

Optimization of antifungal production by an alkaliphilic and halotolerant actinomycete, Streptomyces sp. SY-BS5, using response surface methodology

Journal De Mycologie Medicale, Jun 1, 2015

Optimization of medium components and physicochemical parameters for antifungal production by an ... more Optimization of medium components and physicochemical parameters for antifungal production by an alkaliphilic and salt-tolerant actinomycete designated Streptomyces sp. SY-BS5; isolated from an arid region in south of Algeria. The strain showed broad-spectrum activity against pathogenic and toxinogenic fungi. Identification of the actinomycete strain was realized on the basis of 16S rRNA gene sequencing. Antifungal production was optimized following one-factor-at-a-time (OFAT) and response surface methodology (RSM) approaches. The most suitable medium for growth and antifungal production was found using one-factor-at-a-time methodology. The individual and interaction effects of three nutritional variables, carbon source (glucose), nitrogen source (yeast extract) and sodium chloride (NaCl) were optimized by Box-Behnken design. Finally, culture conditions for the antifungal production, pH and temperature were studied and determined. Analysis of the 16S rRNA gene sequence (1454 nucleotides) assigned this strain to Streptomyces genus with 99% similarity with Streptomyces cyaneofuscatus JCM4364(T), the most closely related. The results of the optimization study show that concentrations 3.476g/L of glucose, 3.876g/L of yeast extract and 41.140g/L of NaCl are responsible for the enhancement of antifungal production by Streptomyces sp. SY-BS5. The preferable culture conditions for antifungal production were pH 10, temperature 30°C for 09 days. This study proved that RSM is usual and powerful tool for the optimization of antifungal production from actinomycetes.

Extraction et purification de l’exo-p-(i-3)-glucanase du suc digestif d’escargot (Helix pomatia)

Extraction et purification de l'exo-P-(1-3)-glucanase du suc digestif d'escargot (Helix pomatia). Étude de la protoplastisation sur Saccharomyces cerevisiae

L'extraction et la purification de la β-(1,3)-glucanase du suc d'Helix pomatia par precip... more L'extraction et la purification de la β-(1,3)-glucanase du suc d'Helix pomatia par precipitation au sulfate d'ammonium 25, 40, 60 et 80% montre que la fraction 40% presente une meilleure activite specifique 17U/mg avec un rendement de 24,40%, L'elution chromatographique de la fraction -40% indique que les eluats compris entre les tubes 25 et 31 constituent un seul pic avec un maximum d'activite specifique a 104 U/mg. Ces eluats rassembles forme la fraction dite '25-31' avec une activite specifique de 161 U/mg et un rendement de 2%. L'etude comparative de la protoplastisation de la levure Saccharomyces cerevisiae avec la cytohelicase commerciale et la preparation enzymatique obtenue a ete realisee avec et sans pretraitement au mercapto-ethanol. Les rendements sans pretraitement s'averent dans les deux cas trop faibles, par contre les rendements obtenus avec un pretraitement sont de 83 et 80% respectivement avec la cytohelicase commerciale et l'extrait enzymatique. Par ailleurs, les taux de protoplastisation pourraient etre ameliores en utilisant des cellules en phase de croissance de 15 heures de culture et avec une concentration d'enzyme egale a 0,022mg/ml.

Etude Des Phenotypes De Resistance Aux -Lactamines Des Souches D’Enterobacteries Isolees en Milieu Hospitalier : Cas De L’Hopital D’Amizour (W. Bejaia)

Sciences & Technologie, Jun 1, 2003

Taxonomy and Study of Antimicrobial Activity of Two HalophilicActinomycetes AH1 and AH2 Isolated from a Saline Soil of Bejaia(Algeria)

Research and reviews in biosciences, 2012

In this study we are interested in the taxonomic characterization of two isolates of halophilic a... more In this study we are interested in the taxonomic characterization of two isolates of halophilic actinomycetes, the identification of their antimicrobial and antifungal activities, and the determination of the chemical nature of bioactive molecules. Both strains AH1 and AH2 were isolated from saline soil in the region of Bejaia (Algeria). Based on morphological and chemotaxonomic characteristics, these isolates AH1 and AH2 are related to the genus Streptomyces. The growth and the antibiotic production by the two isolates are evaluated on two liquid culture media (ISP2 and M2) at different concentrations of NaCl. The results obtained showed that the antibiotic activity (antibacterial and antifungal) is very important. Extraction of antibiotic from Crude extracts by dichloromethane and n-butanol from the culture filtrate of the isolate AH1 and AH2 respectively, showed good activities, also, the crude extracts with hexane for both isolates showed a very important antifungal activity. The antibiotic complexes were located by bioautgraphy, and suggest that these molecules belong to subfamilies of aminoglycosides and polyether, and these antibiotics are non-polyenic.

Physiology and growth of Pyrococcus sp. HT3 in bach culture with cellobiose and maltose as the principal carbon sources

BioTechnology: An Indian Journal, 2012

The hydrothermal hot spring archaeonPyrococcussp. T3 was grown in batch cultures in closed bottle... more The hydrothermal hot spring archaeonPyrococcussp. T3 was grown in batch cultures in closed bottles, both in the presence and in the absence of elemental sulfur. Growth on carbohydrates, proteinaceous substrates and amino acids was investigated. The disaccharides maltose and cellobiose were shown not to be able to enhance growth suggesting that Pyrococcussp. T3 is unable to use them as sole carbon sources. By contrast, proteinaceous substrates such as peptone and brain heart infusion were shown to be very good substrates for the growth of Pyrococcussp. T3. Growth on brain heart infusion was shown to require additional nutrients when sulfur was not present in the culture medium. Growth on amino acids only took place in the presence of sulfur. These results indicate that sulfur plays an important role in the metabolism and energetics of Pyrococcussp. HT3.

Statistical Medium Optimization for the Production of Anti-Methicillin-Resistant Staphylococcus aureus Metabolites from a Coal-Mining-Soil-Derived Streptomyces rochei CMB47

Fermentation, Apr 15, 2023

This article is an open access article distributed under the terms and conditions of the Creative... more

Characterization of a Haloalkaline Nocardiopsis sp. Strain S10 Isolated from Wastewater and Optimization of Culture Medium for Improving Production of Antifungal Compounds

Anti-Infective Agents

Background: The emerging antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG... more Background: The emerging antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are a pressing global concern. Furthermore, the limited number of available antifungal agents requires the discovery of new antimicrobials. Introduction: This paper focused on the isolation and characterization of an actinobacterium designated S10, the study of its antimicrobial activity, on the one hand, and the optimization of antifungal production using statistical methods, on the other hand. Methods and Results: A haloalkaliphilic actinobacterium designated S10 was isolated from a wastewater treatment plant in the Souk-El-Tenine region (Bejaia, Algeria). This strain showed a broad spectrum of activity against bacteria (B. subtilis, L. innocua, M. luteus, S. aureus, MRSA, E. coli, P. aeruginosa, S. Typhi, and V. cholerae), molds (A. niger, G. geotricum, and F. oxysporum) and a pathogenic yeast (C. albicans). The extracellular enzymes producer Nocardiopsis sp. S10 was identified bas...