The consortium of Bacillus cereus (DQ002384), Serratia marcescens (AY927692) and Serratia marcescens (DQ002385) were used for pentachlorophenol (PCP) degradation. The consortia showed better overall removal efficiencies than single strains by utilization of PCP as a carbon and energy source confirmed by pH dependent dye indicator bromocresol purple (BCP) in mineral salt media (MSM). Mixed culture was found to degrade up to 93% of PCP (300 mg/l) as compared to single strains (62.75-90.33%), at optimized conditions (30 ± 1°C, pH 7 ± 0.2, 120 rpm) at 168 h incubation. PCP degradation was also recorded at 20°C (62.75%) and 37°C (83.33%); pH 6 (70%) and pH 9 (75.16%); 50 rpm (73.33%) and 200 rpm (91.63%). The simultaneous release of chloride ion up to 90.8 mg/l emphasized the bacterial dechlorination in the medium. GC-MS analysis revealed the formation of low molecular weight compound, i.e., 6-chlorohydroxyquinol, 2,3,4,6-tetrachlorophenol and tetrachlorohydroquinone, from degraded sample as compared to control.

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The common Indian freshwater catfish, Hetempnewtea fOa8&3, was exposed t o the 96 h-LCm (0.007-0.013 ppm) of the organochloride thiodan (endosulfan) for 4 days. The stressed fishes showed various histopathological changes. I n the liver, extensive degeneration of cytoplasm, pycnosis of nuclei, and loss of glycogen was observed most commonly. Stasis of circulation and constriction of bile duct lumen was also seen frequently. I n the kidney, shrinkage of glomeruli, cytoplasmic damage and epithelial desquemation in tubules, and extensive degeneration of hemopoietic stroma was commonly observed. I n the intestine, the damage was comparatively negligible, the most common effect was an increased mucus cell aotivity leading t o accumulation of mucoid exudates in the lumen.

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Behaviour of Heteropneustes fossilis under Stress of Thiodan To xi citySumniury: The freshwater catfish, H . fossdis, exposed to the 96 h-LCjo (0.007 ... 0.013 ppm) of the organochlorine thiodan (endosulfan) for 4 days, developed behavioiiral anomalies within 30 niin of exposure. Increased opercalar movement rate, greater frequency of surfacing for gulping air, restIessnFss, aimless wandering, tendency to move individually instead of in groups, let,hargy and disoriented locomotion were commonly observed and became marked by the end of 12 h of exposure. Subseqiiently, some individualstended to recover while others developed uncontrolled, continuous and irreversible contortions and died.

Singh et al.: Effect of pyridine and formaldehyd on Lemna minor L and Tubifex tubifex Müller in freshwater microcosmsAbstract. Pyridine, a suspected genotoxic and formaldehyde, a potent carcinogen, are present in several industrial wastewater including commercial solvent, resin and pesticide manufacturing industries. The extent of pyridine and formaldehyde toxicity in aquatic organisms is unknown. Therefore, in present study the toxicity of pyridine and formaldehyde were investigated in artificial aquatic ecosystem (microcosm) using two freshwater organisms of different trophic levels i.e. a common duckweed; Lemna minor L. and an oligochaete; Tubifex tubifex Müller. In microcosm, formaldehyde was found to be more toxic to chlorophyll (21 days IC50 = 0.08±0.02 mgL-1), protein (21 days IC50 = 0.15±0.02 mgL-1) and biomass (21 days IC50 = 0.18±0.02 mgL-1) contents of L. minor than pyridine. In addition, pyridine was found growth supportive to L. minor at concentration of 0.1-0.3 mgL-1. Formaldehyde was found more toxic than pyridine for T. tubifex. Lethal concentrations for formaldehyde were 0.08±0.004 (LC10-21 days), 0.2±0.03 (LC25-21 days) and 0.39±0.05 mgL-1 (LC50-21 days). For pyridine, lethal concentrations were 0.85±0.08 (LC10-21 days), 2.14±0.2 (LC25-21days) and 4.27±0.3 mgL-1 (LC50-21days). The concentration and time dependent decrease in growth rate, soluble protein and glycogen content was observed. To overcome the stress situation, high-energy requirement of worms lead to protein and glycogen catabolism. The results of present study might be an important consideration while assessing the hazards of materials to aquatic organisms or when deriving water quality criteria for aquatic organisms.