Papers by Luca Chiodaroli
Molecules/Molecules online/Molecules annual, May 1, 2024
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Microbiology, Dec 1, 2015
Pseudomonas aeruginosa is an opportunistic pathogen known to be resistant to different classes of... more Pseudomonas aeruginosa is an opportunistic pathogen known to be resistant to different classes of antibiotics and disinfectants. P. aeruginosa also displays a certain degree of tolerance to photodynamic therapy (PDT), an alternative antimicrobial approach exploiting a photo-oxidative stress induced by exogenous photosensitizers and visible light. To evaluate whether P. aeruginosa pigments can contribute to its relative tolerance to PDT, we analysed the response to this treatment of isogenic transposon mutants of P. aeruginosa PAO1 with altered pigmentation. In general, in the presence of pigments a higher tolerance to PDT-induced photooxidative stress was observed. Hyperproduction of pyomelanin makes the cells much more tolerant to stress caused by either radicals or singlet oxygen generated by different photosensitizers upon photoactivation. Phenazines, pyocyanin and phenazine-1-carboxylic acid, produced in different amounts depending on the cultural conditions, are able to counteract both types of PDT-elicited reactive oxygen species. Hyperproduction of pyoverdine, caused by a mutation in a quorum-sensing gene, rendered P. aeruginosa more tolerant to a photosensitizer that generates mainly singlet oxygen, although in this case the observed tolerance to photooxidative stress cannot be exclusively attributed to the presence of the pigment.
Microbiologia medica, Mar 31, 2011
Purificazione e attività antimicrobica di estratti ottenuti da foglie di piante africane apparten... more Purificazione e attività antimicrobica di estratti ottenuti da foglie di piante africane appartenenti alla famiglia delle Combretaceae SUMMARY The dry leaves of two African plants of the Combretaceae family, furnished by the botanist of the St. Jean de Dieu hospital of Tangueità (Benin, central Africa), were extracted with a sequence of 5 solvents with increasing polarity (from cyclohexane to water).The raw materials, obtained from these extractions following solvent evaporations, were tested for antibiotic activity against gram negative and gram positive bacterial strains. According to the results of a modified Kirby-Bauer test, no promising effect was obtained against Gram negative bacteria while interesting dose-effect activities were observed against Gram positive strains. In particular, from G. senegalensis active compounds were found in the low polarity extract (dichloromethane) which, at a concentration of 800 µg/disk (13 mm diameter disk), resulted in a grow inhibition crown of 4.7 mm and 2.6 mm on Enterococcus faecalis and Staphylococcus aureus MSSA, respectively. An higher amount of the aqueous extract (4760 µg/disk) also produced a good result as 5.7 mm and 5.0 mm crowns were observed. The extracts from C. micranthum showed an inhibiting effect in the more polar extracts (i.e. from ethanol and water) which gave 1 mm of grow inhibition crown on both strains at a concentration of 1000 µg/disk. The most promising extract from each plant was partially purified and then tested on some clinical relevant bacterial strains: S. aureus MRSA, Clostridium difficile, Streptococcus pyogenes, Streptococcus pneumoniae, Corynebacterium striatum, Neisseria gonorrhoeae, Haemophylus influenzae, Escherichia coli, obtaining a good killing effects on the Gram positive bacteria of the panel.
Research Journal of Microbiology, Feb 1, 2014
Functional Foods in Health and Disease, 2017
Background: Mushrooms produce a large amount of medicinal compounds, and are also an optimal sour... more Background: Mushrooms produce a large amount of medicinal compounds, and are also an optimal source of fibres, proteins, vitamins (like groups B and D), and other micronutrients including potassium, magnesium, etc. Consequently, mushrooms are commonly considered to be functional foods. Many works report the high biological potentials of medicinal mushrooms involving their antibacterial, hypoglycaemic, anticholesterolemic, radical scavenging, and anti-inflammatory effects.Context and purpose of this study: First off, this work aimed to find strains of Lentinula edodes and Pleurotus ostreatus from a bank of edible mushrooms bought from international strain banks (Table I) that could possess health benefit related properties, such as a radical scavenging activity (antioxidant effect), antibacterial effects against common pathogenic bacteria, and being able to produce interesting nutrients and secondary metabolites. As the fungal bank comprises of 20 strains of L. edodes and 20 strains ...
Microbiology, 2015
Pseudomonas aeruginosa is an opportunistic pathogen known to be resistant to different classes of... more Pseudomonas aeruginosa is an opportunistic pathogen known to be resistant to different classes of antibiotics and disinfectants. P. aeruginosa also displays a certain degree of tolerance to photodynamic therapy (PDT), an alternative antimicrobial approach exploiting a photo-oxidative stress induced by exogenous photosensitizers and visible light. To evaluate whether P. aeruginosa pigments can contribute to its relative tolerance to PDT, we analysed the response to this treatment of isogenic transposon mutants of P. aeruginosa PAO1 with altered pigmentation. In general, in the presence of pigments a higher tolerance to PDT-induced photooxidative stress was observed. Hyperproduction of pyomelanin makes the cells much more tolerant to stress caused by either radicals or singlet oxygen generated by different photosensitizers upon photoactivation. Phenazines, pyocyanin and phenazine-1-carboxylic acid, produced in different amounts depending on the cultural conditions, are able to counteract both types of PDT-elicited reactive oxygen species. Hyperproduction of pyoverdine, caused by a mutation in a quorum-sensing gene, rendered P. aeruginosa more tolerant to a photosensitizer that generates mainly singlet oxygen, although in this case the observed tolerance to photooxidative stress cannot be exclusively attributed to the presence of the pigment.
Butyric acid, a short chain fatty acid (SCFA), has been reported to protect fish gut structure an... more Butyric acid, a short chain fatty acid (SCFA), has been reported to protect fish gut structure and having an anti-inflammatory property. It may be either introduced with feed or produced by intestinal bacteria, resulting of great relevance when high percentage fish meal (FM) substitutions with vegetable proteins (VP) is operated (Plöger et al., 2012, Tacon et Metian, 2008). So, monitoring the residual butyrate concentration in the fish gut content, may result of paramount importance when tuning fish feed formulation. The volatility of butyrate allowed to quantify the molecule in fish feces by the headspace method with GC-Mass (Valero et al.,2000).The method consisted in acidification and heating of feces in order to evaporate the butyrate. Many parameters (initial temperature and the characteristics of the ramp) have been challenged, in order to find the best analytical conditions and to avoid errors due to contaminants.
Research Journal of Microbiology, 2014
Microbiologia Medica, 2011
Purificazione e attività antimicrobica di estratti ottenuti da foglie di piante africane apparten... more Purificazione e attività antimicrobica di estratti ottenuti da foglie di piante africane appartenenti alla famiglia delle Combretaceae SUMMARY The dry leaves of two African plants of the Combretaceae family, furnished by the botanist of the St. Jean de Dieu hospital of Tangueità (Benin, central Africa), were extracted with a sequence of 5 solvents with increasing polarity (from cyclohexane to water).The raw materials, obtained from these extractions following solvent evaporations, were tested for antibiotic activity against gram negative and gram positive bacterial strains. According to the results of a modified Kirby-Bauer test, no promising effect was obtained against Gram negative bacteria while interesting dose-effect activities were observed against Gram positive strains. In particular, from G. senegalensis active compounds were found in the low polarity extract (dichloromethane) which, at a concentration of 800 µg/disk (13 mm diameter disk), resulted in a grow inhibition crown of 4.7 mm and 2.6 mm on Enterococcus faecalis and Staphylococcus aureus MSSA, respectively. An higher amount of the aqueous extract (4760 µg/disk) also produced a good result as 5.7 mm and 5.0 mm crowns were observed. The extracts from C. micranthum showed an inhibiting effect in the more polar extracts (i.e. from ethanol and water) which gave 1 mm of grow inhibition crown on both strains at a concentration of 1000 µg/disk. The most promising extract from each plant was partially purified and then tested on some clinical relevant bacterial strains: S. aureus MRSA, Clostridium difficile, Streptococcus pyogenes, Streptococcus pneumoniae, Corynebacterium striatum, Neisseria gonorrhoeae, Haemophylus influenzae, Escherichia coli, obtaining a good killing effects on the Gram positive bacteria of the panel.
Uploads
Papers by Luca Chiodaroli