Brevibacillus laterosporus strain BPM3, a potential biocontrol agent isolated from a natural hot water spring of Assam, India.

A bacterial strain designated as BPM3 isolated from mud of a natural hot water spring of Nambar Wild Life Sanctuary, Assam, India, strongly inhibited growth of phytopathogenic fungi (Fusarium oxysporum f. sp. ciceri, F. semitectum, Magnaporthe grisea and Rhizoctonia oryzae) and gram-positive bacterium (Staphylococcus aureus). The maximum growth and antagonistic activity was recorded at 30°C, pH 8.5 when starch and peptone were amended as carbon and nitrogen sources, respectively. In greenhouse experiment, this bacterium (BPM3) suppressed blast disease of rice by 30-67% and protected the weight loss by 35-56.5%. The maximum disease protection (67%) and weight loss protection (56.5%) were recorded when the bacterium was applied before 2 days of the pathogen inoculation. Antifungal and antibacterial compounds were isolated from the bacterium which also inhibited the growth of these targeted pathogens. The compounds were purified and on spectroscopic analysis of a purified fraction having R(f) 0.22 which showed strong antifungal and antibacterial activity indicated the presence of C-H, carbonyl group, dimethyl group, -CH(2) and methyl group. The bacterium was characterized by morphological, biochemical and molecular approaches and confirmed that the strain BPM3 is Brevibacillus laterosporus.

Optimization of medium and cultivation conditions for L-amino acid oxidase production by Aspergillus fumigatus.

A fungal strain was selected from the microbial repository of the North-East Institute of Science and Technology, Jorhat, India, which could produce a high yield of L-amino acid oxidase. 18SrRNA, ITS1, 5.8SrRNA ITS2, and partial 28 S rRNA sequencing and phenotypic characteristics indicate that it belong to the species Aspergillus fumigatus (designated as P13). Maximum production of enzyme (59.55 x 10-3 U/mg dry cell mass) was obtained in a medium containing 10 g/L glucose, 4 g/L yeast extract, and 4 g/L ammonium sulfate, with 20 mmol/L of L-threonine as the inducer. The optimum temperature for enzyme production was 30 degrees C at pH 7.0, with a shaking speed of 200 r/min. At 96 h, the enzyme activity was maximum. The A. fumigatus P13 L-amino acid oxidase accepts a broad substrate range, and the maximum enzyme activity (20.41 x 10-3 U/mg dry cell mass) was obtained with 50 mmol/L of L-tyrosine. In the literature, no reports have been found regarding the production of L-amino acid oxidase by A. fumigatus. The enzyme showed enantiomerically pure amino acid formation, which has tremendous demand in industrial applications.

Agar immobilized yeast cells in tubular reactor for ethanol production.

Saccharomyces cerevisiae cells were immobilized in agar gel and used in a tubular reactor for conversion of cane molasses to ethanol at 30 degrees C, pH 4.5. Reactor was used in a continuous operation to test the operational stability and ethanol productivity. After 100 days of continuous fermentation at a dilution rate of 0.67 hr-1, some deactivation of cells was observed, but ethanol productivity was recovered by reactivating the cells by sparging air intermittently. It was found that intermittent reactivation during continuous operation was very important for satisfactory performance of the reactor. During operation, gel beads maintained their rigidity. Maximum ethanol concentration (94.9 g/L) was obtained with a feed containing 255 g/L reducing sugar, at a dilution rate of 0.2 hr-1. Maximum volumetric productivity (79.5 g ethanol /L/hr), specific ethanol productivity (0.58 g ethanol/g cells/hr), specific sugar uptake rate (1.12 g sugar/g cells/hr) and ethanol yield coefficient (0.43 g ethanol/g sugar) were obtained with a feed containing 195 g/L reducing sugar at a dilution rate of 1.33 hr-1.

Filariasis in the labour population of a tea estate in Upper Assam.

Preliminary random and mass blood surveys undertaken between 2000-0100 h in a tea garden of Upper Assam revealed more than 8 per cent positivity for microfilaria (mf) of Wuchereria bancrofti. The mf carriers were considerably high among males (73) as compared to females (48). Culex quinquefasciatus was incriminated as a vector with man hour density of 68.5 in human dwellings (indoors). The detection of mf in children who had never moved from the area and filaria larvae in vector mosquitoes collected from human dwellings indicate that indigenous transmission is going on in the garden and that filariasis has become a local health problem.

Effect of growth temperature and media composition on the fatty acid composition of Bacillus stearothermophilus AN 002.

The influence of growth temperature, media composition and cell age on the chemical composition of Bacillus stearothermophilus strain AN 002 has been determined. The total cellular protein decreased and the free amino acid content increased with growth temperature, in both exponential and stationary growth phase. The protein and free amino acid contents of cells were higher in the stationary phase than in the exponential phase, irrespective of growth temperature and media composition. The RNA content was only reduced in cells grown at 55 degrees C. No significant variations were observed in the DNA and carbohydrate contents with respect to growth temperature and cell age. The total lipid and fatty acid compositions on the other hand varied as a function of growth temperature, cell age and media composition. Differences in the relative concentrations of even, odd and branched chain fatty acids were noticed. No variation was observed in the antiiso and unsaturated fatty acids with respect to growth temperature. The unique variations in the fatty acid composition and total lipids at the growth temperature of 50 degrees C and their variations in the stationary growth phase seem to be characteristic for B. stearothermophilus AN 002.

Interference with sporulation can stimulate the rate of a proteinase synthesis in Bacillus megaterium.

Bacillus megaterium, in which sporulation was blocked either by mutation or with netropsin, synthesizes during the stationary phase more exocellular proteinase than the sporulating culture. The asporogenic mutant synthesizes the enzyme at a higher rate and for a longer time than does the sporulating population. The culture, whose sporulation was inhibited by netropsin, produces the proteinase at a higher rate, although for only a limited time interval.