Seasonal dynamics of phytoplankton population and water quality in Bidoli reservoir.

Seasonal water quality analysis helps to evaluate the impact of anthropogenic activities on reservoirs. The water quality may be judged by estimating various chemical parameters like dissolved oxygen (DO), free CO2, total alkalinity, total hardness, pH, Ca++, Mg++, Cl-, NO3-, SO4- bicarbonate, and total dissolved solids (TDS) along with environmental parameters like rainfall and temperature. Most of these abiotic factors are subject to human interventions and are interrelated. This cumulative effect directly influences the biota of the reservoir ecosystem where plankton communities are significant. The current work was carried out with the goal to understand the effect of abiotic factors on planktonic growth in a medium-sized artificial reservoir. The study was attempted to analyze two objectives, which were the variations of parameters with respect to three distinct seasons encountered in the region (summer, monsoon, and winter) and second being the impact of such varying parameters on countable/detectable planktonic diversity. From the water samples collected, 44 genera of planktons belonging to Cyanophyceae, Chlorophyceae, Dinophyceae, Desmids, Bacillariophyceae, and Euglenozoa were identified. There was a marked variation in the seasonal parameters pH, EC, temperature, CO2, and HCO3-. Comparison to the BIS and WHO values shows that though water is not potable, it can be used for agriculture and fishing. Thus, it is necessary that this predominantly rainfed reservoir be maintained for sustainable use.

Fermentation behavior of osmophilic yeast Candida tropicalis isolated from the nectar of Hibiscus rosa sinensis flowers for xylitol production.

Eighteen yeast species belonging to seven genera were isolated from ten samples of nectar from Hibiscus rosa sinensis and investigated for xylitol production using D-xylose as sole carbon source. Amongst these isolates, no. 10 was selected as the best xylitol producer and identified as Candida tropicalis on the basis of morphological, biochemical and 26S rDNA sequencing. C. tropicalis produced 12.11 gl(-1) of xylitol in presence of 50 gl(-1) of xylose in 72 h at pH 5, 30°C and 200 rpm. The strain of C. tropicalis obtained through xylose enrichment technique has resulted in a yield of 0.5 gg(-1) with a xylitol volumetric productivity of 1.07 gl(-1)h(-1) in the presence of 300 gl(-1) of xylose through batch fermentation. This organism has been reported for the first time from Hibiscus rosa sinensis flowers. Realizing, the importance of this high valued compound, as a sugar substitute, xylose enrichment technique was developed in order to utilize even higher concentrations of xylose as substrate for maximum xylitol production.

Bacillus sphaericus: the highest bacterial tannase producer with potential for gallic acid synthesis.

An indigenously isolated strain of Bacillus sphaericus was found to produce 1.21 IU/ml of tannase under unoptimized conditions. Optimizing the process one variable at a time resulted in the production of 7.6 IU/ml of tannase in 48 h in the presence of 1.5% tannic acid. A 9.26-fold increase in tannase production was achieved upon further optimization using response surface methodology (RSM), a statistical approach. This increase led to a production level of 11.2I U/ml in medium containing 2.0% tannic acid, 2.5% galactose, 0.25% ammonium chloride, and 0.1% MgSO(4) pH 6.0 incubated at 37°C and 100 rpm for 48 h with a 2.0% inoculum level. Scaling up tannase production in a 30-l bioreactor resulted in the production of 16.54 IU/ml after 36 h. Thus far, this tannase production is the highest reported in this bacterial strain. Partially purified tannase exhibited an optimum pH of 5.0 with activity in the pH range of 3 to 8; 50°C was the optimal temperature for activity. Efficient conversion of tannic acid to purified gallic acid (90.80%) was achieved through crystallization.

Characterization of cross-linked immobilized lipase from thermophilic mould Thermomyces lanuginosa using glutaraldehyde.

Cross-linked enzyme aggregates (CLEAs) have emerged as an interesting biocatalyst design for immobilization. Using this approach, a 1,3 regiospecific, alkaline and thermostable lipase from Thermomyces lanuginosa was immobilized. Efficient cross-linking was observed when ammonium sulphate was used as precipitant along with a two fold increase in activity in presence of SDS. The TEM and SEM microphotographs of the CLEAs formed reveal that the enzyme aggregates are larger in size as compared to the free lipase due to the cross-linking of enzyme aggregates with glutaraldehyde. The stability and reusability of the CLEA with respect to olive oil hydrolysis was evaluated. The CLEA showed more than 90% residual activity even after 10 cycles of repeated use.

Production of milk-clotting protease from Bacillus subtilis.

An indigenous Bacillus subtilis strain isolated from soil was found to be a potent milk-clotting protease (mcp) producer. Production optimized using response surface methodology (RSM) yielded 1,190 U/ml of enzyme in medium containing 6% fructose, 1% casein, 0.3% NH4NO3, 10 mM CaCl2, pH 6.0 and inoculated with 3% inoculum and incubated at 250 rpm for 72 h. Solid-state fermentation resulted in 1,080 and 952.3 U/gds of milk-clotting protease using soybean meal and rice bran, respectively, with higher proteolytic values of 18.97 and 9.1 IU/gds. Production in a biphasic system using an overlay of RSM-optimized medium on solid layer of 6% fructose and 1% casein with 1.5% agar resulted in significant enzyme production. Maximum mcp was obtained using a biphasic system where solid: liquid ratio of 3.0 resulted in a final yield of 1,276.65 U/ml with a yield index of 1.80 as compared to static liquid culture. However, significant increase or difference was noted as compared to yield obtained after RSM. This is the first report on the use of RSM for production of mcp from a bacterial species.

Anaerobic fermentative production of lactic acid using cheese whey and corn steep liquor.

Cheese whey was the most suitable substrate for production of lactic acid under anaerobic conditions by Entercoccus flavescens which, on supplementating with corn steep liquor (5% v/v) and 10 mM CaCO(3) at pH 5.5, 37 degrees C, yielded 12.6 g lactic acid/l in 36 h. Production was scaled up to a 10 l bioreactor under controlled pH and continuous CO(2) supply and gave 28 g lactic acid/l in 30 h resulting in a net 8.7-fold increase in production as compared to unoptimized conditions.

Statistical optimization for succinic acid production from E. coli in a cost-effective medium.

Response surface methodology (RSM) was employed for optimization of medium components and cultural parameters in cost effective cane molasses based medium for attaining high yield of succinic acid. The important factors obtained by "one-variable-at-a-time-approach" (cane molasses, corn steep liquor, sodium carbonate, and inoculum density) were further optimized by RSM. The optimum values of the parameters obtained through RSM (cane molasses 12.5%, corn steep liquor 7.5%, and sodium carbonate 25 mM) led to almost double yield of succinic acid (15.2 g/l in 36 h) as against "one-variable-at-a-time-approach" (7.1 g/l in 36 h) in 500-ml anaerobic bottles containing 300-ml cane molasses based medium. Subsequently, in 10-l bioreactor succinic acid production from Escherichia coli was further improved to 26.2 g/l in 30 h under conditions optimized through RSM. This fermentation-derived succinic acid will definitely help in replacing existing environmentally hazardous and cost-intensive chemical methods for the production of succinic acid.

A highly thermostable and alkaline amylase from a Bacillus sp. PN5.

A highly thermostable alkaline amylase producing Bacillus sp. PN5 was isolated from soil, which yielded 65.23 U mL(-1) of amylase in medium containing (%) 0.6 starch, 0.5 peptone and 0.3 yeast extract at 60 degrees C, pH 7.0 after 60 h of incubation. Maximum amylase activity was at pH 10.0 and 90 degrees C. The enzyme retained 80% activity after 1 h at pH 10.0. It exhibited 65% activity at 105 degrees C and had 100% stability in the temperature range between 80 and 100 degrees C for 1 h. In addition, there was 86.36% stability after 1-h incubation with sodium dodecylsulphate. These properties indicated possible use of this amylase in starch saccharification and detergent formulation.