A novel hybrid technology for remediation of molasses-based raw effluents.

A novel three-step technology for treatment of four molasses-based raw industrial effluents, varying in their COD, color and turbidity is reported here. Sequential steps involved in this treatment are; (1) sonication of the effluents, (2) whole-fungal treatment of these by a ligninolytic marine fungus and (3) biosorption of the residual color with heat-inactivated biomass of the same fungus. Sonication reduced the foul odor and turbidity of the effluents. It increased biodegradability of the effluents in the second stage of treatment. Laccase production in the presence of all the four effluents was directly correlated with their decolorization. After the third step, a reduction of 60-80% in color, 50-70% in COD and 60-70% in total phenolics were achieved. Comparative mass and nuclear magnetic resonance spectra indicated increasing degradation of the effluent components after each stage. Toxicity (LC(50) values) against Artemia larvae was reduced by two to five folds.

Four marine-derived fungi for bioremediation of raw textile mill effluents.

Textile dye effluents pose environmental hazards because of color and toxicity. Bioremediation of these has been widely attempted. However, their widely differing characteristics and high salt contents have required application of different microorganisms and high dilutions. We report here decolorization and detoxification of two raw textile effluents, with extreme variations in their pH and dye composition, used at 20-90% concentrations by each of the four marine-derived fungi. Textile effluent A (TEA) contained an azo dye and had a pH of 8.9 and textile effluent B (TEB) with a pH of 2.5 contained a mixture of eight reactive dyes. The fungi isolated from mangroves and identified by 18S and ITS sequencing corresponded to two ascomycetes and two basidiomycetes. Each of these fungi decolorized TEA by 30-60% and TEB by 33-80% used at 20-90% concentrations and salinity of 15 ppt within 6 days. This was accompanied by two to threefold reduction in toxicity as measured by LC(50) values against Artemia larvae and 70-80% reduction in chemical oxygen demand and total phenolics. Mass spectrometric scan of effluents after fungal treatment revealed degradation of most of the components. The ascomycetes appeared to remove color primarily by adsorption, whereas laccase played a major role in decolorization by basidiomycetes. A process consisting of a combination of sorption by fungal biomass of an ascomycete and biodegradation by laccase from a basidiomycete was used in two separate steps or simultaneously for bioremediation of these two effluents.

Biotransformation of citrinin to decarboxycitrinin using an organic solvent-tolerant marine bacterium, Moraxella sp. MB1.

Organic solvent tolerant microorganisms (OSTMs) are novel group of extremophilic microorganisms that have developed resistance to withstand solvent toxicity. These organisms play an important role in biotransformation of organic compounds. In the present study, we used an organic solvent-tolerant marine bacterium, Moraxella sp. MB1. 16S rRNA sequencing revealed that the bacterium shows 98% similarity with an uncultured marine bacterium with GenBank accession no. AY936933. This bacterium was used for the transformation of a toxin, citrinin, into decarboxycitrinin in a biphasic system. This transformation was affected by decarboxylase enzyme produced by MB1. Transformation of citrinin to decarboxycitrinin was monitored by thin-layer chromatography (TLC) and spectrophotometrically. Citrinin decarboxylase activity responsible for transformation was studied in cell-free growth medium and cell lysate of Moraxella sp. MB1. Citrinin decarboxylase was found to be intracellular in nature. The biotransformed product was purified and identified as decarboxycitrinin using electrospray ionization mass spectrometry (ESI-MS/MS) and nuclear magnetic resonance (NMR) spectrometry. The antibiotic activity of both citrinin and decarboxycitrinin is also reported.