A microbial consortium that can utilize alpha-hexachlorocyclohexane (alpha-HCH) as a sole source of carbon and energy was isolated from soil and sewage through a novel technique involving an initial enrichment in a glass column reactor followed by a shake flask enrichment. This consortium took 14 days to completely mineralize 5 and 10 microg mL(-)(1) alpha-HCH in mineral salts medium in shake flasks. The degradative ability of this consortium improved very markedly on acclimation by successive and repeated passages through media containing increasing concentrations of alpha-HCH. The acclimated consortium could degrade 100 microg mL(-)(1) of alpha-HCH within 72 h at a degradation rate of 58 microg mL(-)(1) day(-)(1) with concomitant release of stoichiometric amounts of chloride. Accumulation of any intermediary metabolites was not detected in the culture broth as tested by TLC and GC, implying complete mineralization of the substrate. The acclimated consortium contained eight bacterial strains and a fungus. The individual strains and the different permutations and combinations of them, however, were able to utilize only 10 microg mL(-)(1) of alpha-HCH. Mesophilic temperatures (20-30 degrees C) and near-neutral pH (6.0-8.0) were most favorable for alpha-HCH degradation. Among the auxiliary carbon sources tested, ethanol, benzoate, and glucose (at higher concentrations) retarded the degradation of alpha-HCH, whereas the addition of cellulose, sawdust, and low concentrations of glucose (<200 microg mL(-)(1)) and acetone enhanced the rate of degradation.

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A mixed culture of a chlorobenzoate-(3-CBA)-degradingPseudomonas aeruginosa, strain 3mT, and a phenol/cresols-degradingPseudomonas sp., strain CP4, simultaneously and efficiently degraded mixtures of 3-CBA and phenol/cresols. However, strains 3mT and CP4 usedortho- andmeta-ring cleavage pathways, respectively. Degradation of 3-CBA was complete when the 3-CBA was equal in amount to or less than that of phenol. CP4/3mT inoculum ratios (w/w) of 1:1 or 1:2 gave the most effective degradation of both the substrates in the mixture. The mixed culture degraded equimolar mixtures of 3-CBA/phenol up to 10MM. Equimolar mixtures of 3-CBA ando-, m- orp-cresol were also degraded by the mixed culture.

The effect of 2,4,5-trichlorophenoxy acetic acid (2,4,5-T) on the germination and seedling vigor of different crop seeds was tested. Seeds of rice, maize, sorghum, finger millet, and horse gram were comparatively more tolerant to the chemical with no marked effect up to a concentration of 200 mg 2,4,5-T L(-)(1) as tested by the filter paper method. Tomato and brinjal (egg plant) were highly susceptible. Even at 5 and 10 mg 2,4,5-T L(-)(1), marked reduction in the germination and seedling vigor of tomato and egg plant, respectively, was observed. At 20 and 30 mg L(-)(1), the germination of tomato and egg plant seeds, respectively, were completely inhibited on filter paper, whereas the inhibitory concentrations in soil was 40 mg 2,4,5-T kg(-)(1) soil. Several abnormalities were observed in the chemically affected seedlings. Protease activity of the seeds germinating in the presence of the chemical was drastically reduced. Bioremediation of the chemically contaminated soil with Burkholderia cepacia AC1100, by inoculation of the soil 7 days before sowing the seeds, completely protected the seeds, resulting in normal germination and an improved seedling vigor.

A Pseudomonas sp. strain, CP4, was isolated that used phenol up to 1.5 g/l as sole source of carbon and energy. Optimal growth on 1.5 g phenol/l was at pH 6.5 to 7.0 and 30°C. Unadapted cells needed 72 h to decrease the chemical oxygen demand (COD) of about 2000 mg/l (from 1 g phenol/l) to about 200 mg/l. Adapted cells, pregrown on phenol, required only 65 h to decrease the COD level to below 100 mg/l. Adaptation of cells to phenol also improved the degradation of cresols. Cell-free extracts of strain CP4 grown on phenol or o-, m- or p-cresol had sp. act. of 0.82, 0.35, 0.54 and 0.32 units of catechol 2,3-dioxygenase and 0.06, 0.05, 0.05 and 0.03 units of catechol 1,2-dioxygenase, respectively. Cells grown on glucose or succinate had neither activity. Benzoate and all isomers of cresol, creosote, hydroxybenzoates, catechol and methyl catechol were utilized by strain CP4. No chloroaromatic was degraded, either as sole substrate or as co-substrate.