Vinod Bihari

High‐Density Cultivation of Sporeformers

Sporeformers are sources of a large number of industrially important biological products including enzymes, antibiotics, and bioinsecticides. Cultivation of these microorganisms to high cell densities offers potential for enhancing the rates of formation as well as the concentration of the desired products in the fermentation broths in bioreactors. With this objective, investigations have been carried out involving fed-batch cultivation of Bacillus thuringiensis, which is known to produce an insecticidal crystal protein during sporulation. With appropriate management of aeration and nutrient supply, it was possible to grow the cells to > 50 g DW/l density. Nevertheless, the achievement of high cell density did not enhance the formation of crystal protein in the same proportion as the cell concentration. Further examination of this system suggested a complex interplay of energetic requirements for protein turnover during sporulation. Energy reserve material, poly-beta-hydroxybutyric acid, appeared to be linked to formation of spores and crystal protein during the sporulation phase.

PRODUCTION OF ANTIBACTERIAL AND ANTIFUNGAL METABOLITES BY STREPTOMYCES VIOLACEUSNIGER AND MEDIA OPTIMIZATION STUDIES FOR THE MAXIMUM METABOLITE PRODUCTION

An antibiotic producing strain Streptomyces violaceusniger was isolated from soil sample, characterized and studied for antibacterial and antifungal activity profile. Fermentation broth and cell extracts were tested against typed test organisms. The activity profiles of the intracellular and extracellular crude extracts showed that the antibiotic producing culture produces two or more compounds, one being intracellular (antifungal), other being extracellular (antibacterial). Broth extract showed activity against E. coli, bacillus subtilis, B. cereus, Pseudomonas aeruginosa and Klebsiella pneumoniae. The cell extract showed activity against Candida albicans, Aspergillus niger, Trichoderma viridae, Fusarium moniliforme and Alternaria brassicicola. Production medium was optimized for antibiotic production.

Production, optimization and purification of an antifungal compound from Streptomyces capoamus MTCC 8123

A microbial isolate showed strong antibacterial and antifungal activity against various multidrug-resistant test organisms. Based on physiological and biochemical characteristics and 16S ribosomal RNA sequence homology studies, it was found to be similar to Streptomyces capoamus (gene sequence similarity 98%). The antifungal metabolite was produced majorly intracellularly. The active metabolite was extracted and purified by gel filtration chromatography and high-performance liquid chromatography (HPLC). Partial chemical characterization of the active compound has been completed. To the best of our knowledge this strain has not been reported to produce antifungal compounds. The paper presented here describes the activity profile of the strain, classical medium optimization, and purification of the antifungal compound.

Production of L-phenylacetyl carbinol by immobilized cells of Saccharomyces cerevisiae.

Conversion of benzaldehyde to l-phenylacetyl carbinol (l-PAC) was achieved with immobilized, growing cells of Saccharomyces cerevisiae in different reactors. Product formation increased (31%) with the subsequent initial reuses of the entrapped cells. Biomass production and PAC formation depleted (40 and 57%, respectively) after 4–5 continuous growth and biotransformation cycles. With the regeneration of the biocatalysts, catalytic activity of the cells was resumed. The highest yields were in a stirred tank reactor (29 g PAC) from 77 g benzeldehyde with 14 repeated uses of entrapped cells.

Production of actinomycin-D by the mutant of a new isolate of Streptomyces sindenensis

An actinomycin-D producing strain was isolated from soil and characterized as Streptomyces sindenensis. The culture was subjected to UV irradiation and a mutant with 400% higher actinomycin-D production was isolated (400 mg/l-1 as compared to 80 mg/l-1 produced by the parent). Production medium was optimized and antibiotic yield with the mutant was enhanced to 850 mg/l-1 which is 963% higher as compared with the parent.

Studies on physiology, zoospore morphology and entomopathogenic potential of the aquatic oomycete: Lagenidium giganteum.

The oomycete Lagenidium giganteum, a facultative parasite of mosquito larvae requires exogenous sterols for the genesis of zoospores when grown saprobically. Growth media prepared from oil rich materials such as soy or sunflower seed were very effective inducers of virulent zoospores. The external morphology of zoospores of L. giganteum was studied with the aid of philips scanning electron microscope 515. Zoospores were ovoid, bluntly pointed with the groove parallel to the long axis and 0.7 × 1.4 μm. Insect cell walls are known to contain lipid and chitin. L. giganteum was tested for chitinase activity and found to possess 0.76 ± SD0.14 chitinase activity. Use of oil seed for growth of the organism confirms phospholipase activity. Phospholipase production was studied further by egg-yolk plate method. Presence of these two key enzymes that can initiate host cell damage suggests the entomopathogenic potential of L. giganteum. L. giganteum failed to grow at 37 °C limiting its effectiveness in warmer climates. Introduction of this organism to variety of habitats with various mosquito species will demonstrate the efficacy of the organism as a bioinsecticide.

Studies on medium optimization for the production of antifungal and antibacterial antibiotics from a bioactive soil actinomycete

A microbial isolate, characterized as Streptomyces sp. (MTCC 6819), produced antifungal metabolite intracellularly and antibacterial metabolite extracellularly under submerged fermentation conditions. This Gram-positive bacterium showed broad antimicrobial activity spectra against both Gram-positive and Gram-negative bacteria. The minimum inhibitory concentration (MIC) of partially purified (68.4%) antibacterial metabolite ranged between 50 and 12.5 μg/mL against multiple-drug-resistant bacteria. The producer organism exhibited strong activity against various yeast and fungi. The MIC values of the partially purified (70%) antifungal metabolite ranged between 6.25 and 3.125 μg/mL for unicellular fungi and 12.5 and 6.25 μg/mL for filamentous fungi. The conditions for the production of these bioactive agents were optimized and the effects of various nutritional factors were studied by classical and statistical methods.

Production of actinomycin-D by a new isolate,Streptomyces sindenensis

An actinomycete strain, designated as C-5, was isolated from the soil sample collected from steel plant effluent sediment. The strain produced actinomycin-D in substantial quantities (80 mg/L). The strain C-5 was taxonomically characterised on the basis of morphological and phenotypic characteristics, genotypic data and phylogenetic analysis. A nearly complete 16S rRNA sequence of the isolate was determined and found to have 100% identity withStreptomyces sindenensis. Streptomyces sindenensis is not reported earlier to produce actinomycin-D. Anticancer activities were determined against various human cancer cell lines. Production of actinomycin-D was scaled up in bench scale fermentors and optimised to a titre of 120 mg/L.

A support-spacer-ligand system for specific affinity adsorption of penicillin acylase

SummaryAn affinity system for specific adsorption of penicillin acylase is reported in the present work. When all the active enzyme was adsorbed by an appropriate amount of carrier, 50% of the total protein containing only inactive portion remained in solution exhibiting strong and preferential adsorption of enzyme.

Growth and enzyme production kinetics of a heparinase-producing fungal isolate

Heparinases are microbially produced enzymes that degrade heparins, the sulfated glycosaminoglycans, to generate low-molecular-weight heparins (LMWHs). A heparinase-producing fungus, Aspergillus oryzae, was isolated from soil sample. The fungus produced heparinase, both extracellularly and intracellularly, in its late log phase of growth. Heparinase production and growth kinetics was studied in complex protein digest medium, with heparin employed as the inducer. Heparinase activity was found to be dependent on the rate of utilization of heparin during growth. Heparin was taken up rapidly in the initial exponential phase of the growth at a rate of 0.16 g cell−1 h−1. Enzyme activity increased at a rate of 1.53 Units h−1 with the exhaustion of heparin in the medium. Enhancement of enzyme production by 92% was achieved by manipulation of the fermentation conditions and medium ingredients.