Papers by Dr.Srividya Shivakumar
Potassium (K) is a very essential element needed by plants for healthy growth and good yield. Mos... more Potassium (K) is a very essential element needed by plants for healthy growth and good yield. Most soils have abundance of potassium underneath in rock as insoluble forms that are unavailable for plant use. This research was carried out to join in the search to unearth microorganisms from the rhizosphere soil that are able to act on the mineral containing substances, solubilizing them to release the needed soluble form of the potassium for plant use. An isolate, which was characterized and identified to be Cellulosimicrobium funkei, showed significant solubilization on feldspar (a potassium containing compound) supplemented media. It is novel for potassium solubilization. The amount of potassium released by the isolate in comparison to reference cultures varied but favourably compared with the reference cultures. In glucose amended broth, solubilization was: Cellulosimicrobium funkei 7.04mg/l, Enterobacter hormaechei 7.15 mg/l and 6.91mg/l for Aspergillus terreus. Urea supplemented broth: Cellulosimicrobium funkei 5.45mg/l, Enterobacter hormaechei 5.38mg/l and Aspergillus terreus 6.33mg/l. KCl supplemented broth: Cellulosimicrobium funkei 10.23mg/l, Enterobacter hormaechei 8.05mg/l and Aspergillus terreus 9.11mg/l. For temperature, the cultures solubilized best at these respective temperatures: Cellulosimicrobium funkei 27 o C, Enterobacter hormaechei 35 o C and Aspergillus terreus 30 o C. P H was 7.5 for Cellulosimicrobium funkei, 8 for Enterobacter hormaechei and for 7.5 for Aspergillus terreus. When they were now cultured using the combination of the above parameters Cellulosimicrobium funkei, Enterobacter hormaechei and Aspergillus terreus gave a maximum yield of 7.24mg/l, 7.03mg/l and 6.81mg/l of solubilized potassium respectively. This means that the isolate Cellulosimicrobium funkei yielded more solubilized potassium from feldspar than the reference cultures and could therefore be a better potassium solubilizer.
Annals of Biological Research, 2013
Plant growth promoting rhizobacteria (PGPR) are beneficial bacteria that colonize plant roots and... more Plant growth promoting rhizobacteria (PGPR) are beneficial bacteria that colonize plant roots and enhance plant growth by a wide variety of mechanisms. Thus the present study focuses on the screening of effective PGPR isolate with multiple traits related to biocontrol of phytopathogenic fungi. In our study, a total of 51 bacterial isolates from the rhizosphere soil samples were isolated and screened for their antagonistic activity against wide range of phytopathogens. Bacterial antagonist showing highest percent and broad spectrum antagonism against fungal phytopathogens was selected and further identified as Pseudomonas aeruginosa FP6 on the basis of 16S rDNA gene sequence analysis. P. aeruginosa FP6 was screened for other plant growth promoting factors like phosphate solubilization, production of IAA, ammonia, siderophore and cell wall degrading enzyme activities- cellulase, chitinase and protease. The isolate was able to solubilize phosphate, produce IAA, siderophore, HCN, ammoni...
International journal of pharma and bio sciences, 2013
Limiting nutrient in the culture conditions is crucial for PHA production. In this study, B. thur... more Limiting nutrient in the culture conditions is crucial for PHA production. In this study, B. thuringiensis IAM 12077 was grown in different culture conditions with limitation of potassium, nitrogen, sulphur and phosphorous. In all the limiting conditions used, a similar range of PHAs were produced with glucose as carbon source (10g/L). The PHA yields and accumulation obtained were found to be 1.61g/L, 65.9%; 1.86g/L, 64.1%; 1.66g/L, 65.9% and 1.7g/L, 68.9% dry cell weight (DCW) for potassium, nitrogen, sulphur and phosphorus limitations, respectively, showing that any of the above deficiency can trigger PHB production in this strain. Time course study in N2 deficient medium revealed that though cell biomass remained almost steady from 0h after transfer to production medium till the end of fermentation (120h), PHB yield showed increase from 0.533 g/L at 0h to 4g/L by 48h and later gradually decreased, with PHB accumulation increase from 11% to 77% by 96h. PCR identified the presence ...
International journal of pharma and bio sciences, 2013
Exploiting the innate hydrolytic enzyme/s potential of the genus Bacillus for costeffective produ... more Exploiting the innate hydrolytic enzyme/s potential of the genus Bacillus for costeffective production of PHAs, using various agro-industrial wastes will contribute to cost reduction and elimination of pre-treatment protocols. PHA producing Bacillus spp. from different rhizospheric soils capable of producing a variety of hydrolytic enzymes were isolated. Two promising isolates: Ti1 and Ti3, from tomato rhizospheric soil samples depicted the PHA yield of 1.44 - 1.6 g/L and the % PHA accumulation of 50.58 and 50.1, respectively. The isolate Ti1 produced amylase, cellulase and protease and Ti3 produced amylase, cellulase, ligninase, lipase and protease of the seven enzymes screened. Combinatorial qualitative innate enzyme based PHA production assay revealed production of PHA by these isolates on some of these complex substrates. Molecular phylogenetic analysis identified Ti3 with close homology to B.megaterium which showed comparable PHA accumulation on starch during preliminary invest...
International Journal of ChemTech Research, 2014
Lactic acid, commonly used in food, chemical and pharmaceutical industries, has recently received... more Lactic acid, commonly used in food, chemical and pharmaceutical industries, has recently received much attention for the production of biodegradable plastics. In this study, Rhizopus oryzae MTCC 8784 was used to convert starch into optically pure L-Lactic acid. Effect of time, pH, addition of calcium car bonate and starch concentration were analyzed using shaker fla sks in order optimize the L-lactic acid concentrati on and volumetric productivity. Under optimized conditions (pH6.0, CaCO 3 (10g/L), starch (10g/L) and 72 h of cultivation) R.oryzae MTCC 8784 gave a lactic acid concentration of 50.48g /L with a volumetric productivity (Q p) of 0.7 (g/L/h) and lactic acid yield(Y P/s) of 4.54 g/g (2 fold increase), 100% starch sacchar ification, and 1.5 g/L mycelial biomass. To reduce the Lactic acid pro duction costs, inexpensive raw materials such as fo od waste (fruit and vegetable peel/waste) like sapota, banan a, papaya, potato, corn cob and carboxymethyl cellu lose were explored. ...
Plant growth promoting rhizobacteria (PGPR) are commonly used as inoculants for improving the gro... more Plant growth promoting rhizobacteria (PGPR) are commonly used as inoculants for improving the growth and yield of agricultural crops. Development of an effe ctive PGPR inoculant necessitates the presence of a diverse set of traits that can help in colonization of the rhizosphere and survival under varying environmental conditions. Thus the present study focuses on the s creening of effective PGPR isolates with multiple t raits related to biocontrol of phytopathogenic fungi. In the present study, 51 Pseudomonas isolates from the rhizospheric soil samples of different crops were s creened initially on the basis of their antagonisti c activity, and fifteen fluorescence Pseudomonas spp. designated FP1-FP15 were selected for further study. These isolates were then tested in vitro for specific PGPR traits such as the production of phosphate solubilizing enzymes, Indole Acetic Acid (IAA), siderophores, Hydrocyanic acid (HCN), salicylic acid, hydrolytic enzymes and biosurfactants. Of the 15...
Applied Biochemistry and Biotechnology, 2011
A fungal isolate, identified as Penicillium citrinum S2, produced ≈1 U/mL of PHB depolymerase by ... more A fungal isolate, identified as Penicillium citrinum S2, produced ≈1 U/mL of PHB depolymerase by 72 h when grown in BHM containing 0.2%, w/v PHB, pH 6.0 at 30°C. Partial purification of an extracellular poly(-β-)hydroxybutyrate (PHB) depolymerase PhaZ Pen from P. citrinum S2 by two steps using ammonium sulphate (80% saturation) and affinity chromatography using concanavalin A yielded 16.18-fold purity and 21.53% recovery of protein. The enzyme was composed of three polypeptide chains of 66, 43 and 20 kDa, respectively, as determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. All the three bands stained positive for glycoprotein by PAS staining. Optimum enzyme activity was detected at pH 6.0 and 50°C. The enzyme was stable between pH 4.0 and 7.0 at 50°C, 2 h. β-hydroxybutyrate monomer was detected as the major end product of PHB hydrolysis. The enzyme also showed distinct behaviour towards different inhibitors tested, which suggests the role of serine, serine residue, carboxyl group, tyrosine and sulfhydryl groups in its active site.
This study presents one-factor approach for optimization of growth and physical parameters for in... more This study presents one-factor approach for optimization of growth and physical parameters for increasing production of three mycolytic enzymes viz. chitinase, β-1,3-glucanase and β1,4-glucanase (cellulase) by B.subtilis, a potent biocontrol agent. Maximum enzyme activity of all three enzymes was observed in the following physical parameters: pH 7.0, temperature of 30°C, and incubation period of 72h. Optimum nutritional parameters were found to be as follows: Carboxymethyl cellulose (CMC, 10g/L); Corn steep liquor (CSL, 1g/L) or KNO3 (1 g/L), CaCl2 (5mM) and Triton X 100 (0.1% v/v). Using one factor approach, production of all three enzymes significantly increased for chitinase (5.49 folds); â-1,3-glucanase (7.39 folds) and cellulase (1.91 folds) respectively as compared to the un-optimized media containing Nutrient broth. The crude mycolytic enzymes had activity in acidic pH (4 6) and temperature (50 60°C) range with optima at pH 6.0 and 55°C, respectively. However, chitinase showe...
Archives of Applied Science Research, 2012
The study aimed at isolating a potential acid protease producing fungal strain from local soil so... more The study aimed at isolating a potential acid protease producing fungal strain from local soil source. The fungal strains were isolated from garden soil on the basis of clearance zone on casein-glycerol agar flooded by coomassie blue stain. Aspergillus sp. showing maximum clearance on casein agar plates (pH 5) was selected for further studies. Optimization of various factors influencing maximum enzyme production by Aspergillus sp. using solid state fermentation was investigated. Optimum fermentation conditions for enzyme production were - substrate (wheat bran & gelatin; 1%, w/v), fermentation time (120 h), moisture content (20 %), growth pH (5.0) and temperature (30oC). Wheat bran supplemented with nitrogen sources viz., gelatin and potassium nitrate showed 15-17 % increase in enzyme productivity. However, supplementation with additional carbon sources or salt solution had no profound influence on enzyme productivity. The crude acid protease of Aspergillus sp. showed pH and tempera...
Biotic and abiotic stresses are major constrains to agricultural production. Among abiotic stress... more Biotic and abiotic stresses are major constrains to agricultural production. Among abiotic stress, drought and salinity are the major environmental factors limiting growth and productivity of many crops including vegetables, particularly in arid and semiarid areas of the world. Abiotic stress causes more than 50% average yield loss worldwide. Globally, demand for vegetables is increasing, and this has boosted the vegetable production in recent times. The substantial increase in production of key vegetables such as tomato, onion, cucumber, eggplant, cauliflower, pepper, lettuce, carrot, and spinach has been recorded. However, vegetables are generally considered more vulnerable than staple crops to stressful environmental conditions including extremes of temperature, drought, salinity, water logging, mineral nutrient excess and deficiency, and changes in soil pH which are likely to be exacerbated by the prevalent climatic change in many parts of the world. Plant growth under stress co...
Biotechnological Applications of Polyhydroxyalkanoates, 2019
Antibiotic resistance is a risk which has gradually become common knowledge. Steps are being acti... more Antibiotic resistance is a risk which has gradually become common knowledge. Steps are being actively taken to limit the use of antibiotics. The meat industry (poultry, piggery and sea food) are prone to infections. Containing these infections becomes cardinal for the meat which is ultimately meant for human consumption. Alternatives are therefore sought. Two alternatives which show promising pathogen containment are short chain fatty acids (SCFA) and Polyhydroxyalkanoates (PHA). SCFA are known to impart bactericidal effect apart from other benefits to the host. PHAs which have been viewed as alternatives to conventional plastic are rich sources of SCFA monomer pools. The most widely studied PHA is Polyhydroxybutyrate (PHB), a homopolymer made of 3-Hydroxybutrate (3HB) monomers. Many studies have been conducted on both SCFA and PHA on their use as biocontrol agents to understand the physiological mechanism of action for both.
Biotechnological Applications of Polyhydroxyalkanoates, 2019
Synthetic plastics have been very well recognized for the packaging industry. An evident inclinat... more Synthetic plastics have been very well recognized for the packaging industry. An evident inclination towards development of biodegradable Bioplastics based on biological material and, particularly for bulk packaging applications has been perceived as a strategy to overcome the dependency of packaging sector on fossil fuels and diminish the biospheric plastic waste burden. The packaging industry demands the raw material in quantity and quality both. Quality includes properties such as ample tensile strength, less brittleness, adequate gas, aroma, ultra-violet (UV) and water barrier properties as per the product to be packaged. The inherent hydrophobicity, biodegradability and enormous property range has branded the microbial poly (hydroxyalkanoates) (PHAs) as promising competitors of petro-plastics in the packaging market. This chapter addresses the basic characteristics and alluring advantages of PHAs as packaging materials. The major focus has been on discussing recent developments...
Turkish Journal of Biology, 2012
A gram-positive bacterium that accumulated poly(3-hydroxybutyric) acid (PHB) was isolated from pe... more A gram-positive bacterium that accumulated poly(3-hydroxybutyric) acid (PHB) was isolated from petrol bunk soil. From its morphological and physiological properties and the nucleotide sequence (about 1.5 kb) of its 16S rDNA, it was identified as Microbacterium barkeri DSM 20145. Based on the available literature, this is the first report of PHB accumulation by Microbacterium sp. The isolate accumulated 0.6 g/L, or 29.7%, of PHB under growth conditions in a nitrogen-deficient medium containing glucose and yeast extract (4:1 ratio), with maximum production by 48 h. The capacity of the isolate to produce PHB under different carbon and nitrogen sources was also investigated. The strain produced appreciable levels of PHB by utilizing hemicellulosic sugars such as glucose, xylose, and arabinose, as well as disaccharides such as lactose and sucrose, alternative carbon sources like wheat bran and carboxymethyl cellulose, and organic acids such as propionic acid, with maximum production achi...
Journal of Scientific & Industrial Research, 2018
Screening of 13 avicelase positive bacterial isolates obtained from soil and leaf litter proved i... more Screening of 13 avicelase positive bacterial isolates obtained from soil and leaf litter proved isolate L4 to be a potent avicelase producer with highest zone of clearance (25 mm) and Enzymatic index of 1.8. The phylogenetic tree constructed on the basis of 16S rRNA gene sequences revealed its closeness to Serratia marcescens WW4 and was designated as Serratia marcescens L4. Maximum avicelase (8.2 IU) production by S. marcescens was supported at pH 7.0, 30°C with CMC (5 g/L). Avicelase production was repressed by sugars and showed non-dependence on metal ions. Among agrowastes, potato peel supported the highest activity (6.4 IU). The enzyme showed pH and temperature optima of 7.0 and 55°C and retained almost 72% activity at 55°C up to 2 h. Enzymatic biofinishing at pH 7.0, 55°C and 2 h incubation revealed some amount of weight loss, indigo dye and reducing sugar release from the denim fabric. Thus the neutral avicelase of S. marcescens may find application in denim biofinishing with...
Polish journal of microbiology, 2009
The study aimed at screening and identifying a potential poly-beta-hydroxybutyrate (PHB) accumula... more The study aimed at screening and identifying a potential poly-beta-hydroxybutyrate (PHB) accumulating Bacillus strain and optimization of media parameters for increased PHB production by the strain. A Gram-positive bacterium that accumulated PHB was isolated from local garden soil of Bangalore. Based on morphological and physiological properties, and nucleotide sequence (about 1.5 kb) of its 16S rDNA it was identified as Bacillus thuringiensis IAM 12077. PHB production was found to be comparable to most of the Bacillus sp. reported to date. PHB production by this strain was dependent on nutrient limitation. Cell dry weight and PHB accumulation increased significantly under biphasic growth condition (from nutrient broth to nitrogen-deficient medium) as compared with growth in nutrient broth alone (from 0.32 g/l to 2.76 g/l cell dry weight; 24% to 43.37% PHB accumulation; 0.2 g/l to 1.2 g/l PHB production), with maximum accumulation at 24 h in nitrogen-deficient medium. Time course st...
Polymeric biomaterials have played an important role in the advancement of modern medicine. Polyh... more Polymeric biomaterials have played an important role in the advancement of modern medicine. Polyhydroxyalkanoates (PHAs) have been established as natural, renewable, nontoxic, biodegradable, and biocompatible thermoplastics since the 20th century. The versatility of PHAs in terms of flexible monomer chemistry and desired surface modifications gives rise to polymers with great physical and mechanical property diversity. Polyhydroxybutyrate (PHB) has been explored as a promising material for biomedical applications. Diverse animal model and tissue response studies on this polymer have suggested it to be a suitable material for fabrication of resorbable medical devices, such as sutures, wound dressings, cardiovascular grafts, bone and cartilage scaffolds, and tissue engineering scaffolds, drug delivery, and nerve guides. Various modification reactions attempted to improve the mechanical, thermal, and hydrophilic properties of the polymer are briefly discussed. The chapter discusses the...
International Journal of ChemTech Research, 2012
Indian Journal of Natural Products and Resources, 2020
Endophytic fungi reside within the plant tissues asymptomatically and produce various secondary m... more Endophytic fungi reside within the plant tissues asymptomatically and produce various secondary metabolites of pharmaceutical interest. The current study aims to bio-prospect medicinal plants for the isolation and screening of lovastatin producing endophytic fungi. Endophytic population in the leaf, stem, root and flower (as applicable) of ten medicinal plants has been studied and their potential to produce the anti-hypercholesterolemia drug, lovastatin has been evaluated. A total of 98 fungal isolates were obtained from the plant tissues and lovastatin yield from them was quantified to be within the range of 5 mg/L to 71.5 mg/L in the first round of submerged fermentation. The subsequent levels of screening witnessed a great change in the yield which could be attributed to gene attenuation, a usual phenomenon in endophytes. A novel lovastatin producer, designated as HL1, belonging to candida sp. residing within the leaves of Hibiscus rosa-sinensis was found to consistently yield hi...
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Papers by Dr.Srividya Shivakumar