Green gram husk--an inexpensive substrate for alkaline protease production by Bacillus sp. in solid-state fermentation.

Alkaline protease production under solid-state fermentation was investigated using isolated alkalophilic Bacillus sp. Among all agro-industrial waste material evaluated, green gram husk supported maximum protease production. Solid material particle size regulated the enzyme production and yield was improved with the supplementation of carbon and nitrogen sources to the solid medium. Optimum enzyme production was achieved with 1.5% maltose and 2.0% yeast extract with 371% increase than control. Glucose did not repressed enzyme production but inorganic nitrogen sources showed little negative impact. The physiological fermentation factors such as pH of the medium (pH 9.0), moisture content (140%), incubation time (60 h) and inoculum level played a vital role in alkaline protease production. The enzyme production was found to be associated with the growth of the bacterial culture.

Xylitol production from corn fiber and sugarcane bagasse hydrolysates by Candida tropicalis.

A natural isolate, Candida tropicalis was tested for xylitol production from corn fiber and sugarcane bagasse hydrolysates. Fermentation of corn fiber and sugarcane bagasse hydrolysate showed xylose uptake and xylitol production, though these were very low, even after hydrolysate neutralization and treatments with activated charcoal and ion exchange resins. Initial xylitol production was found to be 0.43 g/g and 0.45 g/g of xylose utilised with corn fiber and sugarcane bagasse hydrolysate respectively. One of the critical factors for low xylitol production was the presence of inhibitors in these hydrolysates. To simulate influence of hemicellulosic sugar composition on xylitol yield, three different combinations of mixed sugar control experiments, without the presence of any inhibitors, have been performed and the strain produced 0.63 g/g, 0.68 g/g and 0.72 g/g of xylose respectively. To improve yeast growth and xylitol production with these hydrolysates, which contain inhibitors, the cells were adapted by sub culturing in the hydrolysate containing medium for 25 cycles. After adaptation the organism produced more xylitol 0.58 g/g and 0.65 g/g of xylose with corn fiber hydrolysate and sugarcane bagasse hydrolysate respectively.

Biotreatability studies of pharmaceutical wastewater using an anaerobic suspended film contact reactor.

The pharmaceutical industrial effluents, which include several organic solvents and other toxic chemicals, are generally treated by aerobic process, which is cost intensive in nature. The alternative anaerobic route to degrade the toxic effluents is attractive due to the lower cost of treatment and the generation of gas, which can supplement the energy requirements. There are few reports on the anaerobic treatment of the pharmaceutical effluents. In the present investigation, the effluents from a bulk drug industry, which utilizes several organic chemicals, have been taken to assess their applicability for anaerobic treatment. The organic loading rates were varied from 0.25 kg/m3/day to 2.5 kg/m3/day and the COD reduction was found to be in the range of 60 to 80%. Long term operation of an anaerobic suspended film contact reactor carried out with 1.25 kg/m3/day was found to be optimum. The biogas generated during the degradation process was monitored and the methane content was found to be 60-70%.