Acetamide hydrolyzing activity of Bacillus megaterium F-8 with bioremediation potential: optimization of production and reaction conditions

Bacillus megaterium F-8 exhibited an intracellular acetamide hydrolyzing activity (AHA) when cultivated in modified nutrient broth with 3% tryptone, 1.5% yeast extract, and 0.5% sodium chloride, at pH 7.2, 45 °C for 24 h. Maximum AHA was recorded in the culture containing 0.1 M of sodium phosphate buffer, (pH 7.5) at 45 °C for 20 min with 0.2 % of acetonitrile and resting cells of B. megaterium F-8 equivalent to 0.2 ml culture broth. This activity was stable up to 55 °C and was completely inactivated at or above 60 °C. Maximum acyl transferase activity (ATA) was recorded in the reaction medium containing 0.1 M of potassium phosphate buffer, (pH 8.0) at 55 °C for 5 min with 0.85 mM of acetamide as acyl donor and hydroxylamine hydrochloride as acyl acceptor and resting cells of B. megaterium F-8 equivalent to 0.94 mg cells (dry weight basis). This activity was stable up to 60 °C and a rapid decline in enzyme activity was recorded above it. Under the optimized conditions, this organism hydrolyzed various nitriles and amides such as propionitrile, propionamide, caprolactam, acetamide, and acrylamide to corresponding acids. Acyl group transfer capability of this organism was used for the production of acetohydroxamic acid. ATA of B. megaterium F-8 showed broad substrate specificity such as for acetamide followed by propionamide, acrylamide, and lactamide. This amide hydrolyzing and amidotransferase activity of B. megaterium F-8 has potential applications in enzymatic synthesis of hydroxamic acids and bioremediation of nitriles and amides contaminated soil and water system.

Assessment of teratogenecity and embryotoxicity of sludge from textile industries at Pali (India) in Swiss albino mice exposed during organogenetic period

The present investigation was carried out to assess the teratological effects of in-utero exposure of sludge leachate from textile and dyeing industries located in Pali, Rajasthan. Sludge was collected at the combined effluent treatment plant (CETP). Two groups of 10 pregnant Swiss albino mice each, were given sludge leachate of 1/10 and 1/100 dilutions with water ad libitum from 6th day to 15th day of gestation covering the critical period of organogenesis. Cesarean sections were performed on day 18 of gestation and all foetuses were examined for reproductive and teratological tests. Sludge induced maternal toxicity was evidenced by significant increase in leachate consumption, reduction in body weight gain and reduction in fur of the body. Developmental toxicity was evidenced by a significant decrease in foetal weight per litter increase in the number of resorptions and an increase in total number of foetuses showing bone retardation and skeletal variations (specially of skull, sternebrae and vertebrae). The leachate of the sludge that is being dumped in the open areas of the town Pall seems to elicit teratogenic as well as embryotoxic potential as indicated by the findings of the present investigation.

Organochlorine residues in water from the Mahala water reservoir, Jaipur, India

Residues of p,p'-DDE, p,p'-DDT alpha-, beta-, gamma-isomers of HCH, aldrin and heptachlor in water, from four different sites of the Mahala water reservoir were monitored periodically from September 1985 to October 1987. All the samples contained the above residues in varying concentrations. Isomers of HCH predominated and were followed in relative dominance by aldrin, total DDT and heptachlor residues, p,p'-DDE and p,p'-DDD constituted the major fraction of total p,p'-DDT. Monthly total organochlorine residue levels in water ranged between 1.07 and 81.23 microg litre-1. The variation is attributed to the run-off or subsoil water movement from the catchment area.