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We reported our comparative observations on oligotrophs vs. copiotrophs from a hyper-alkaline and hypersaline habitat, Lonar Lake, situated in the Buldhana district of Maharashtra, India. Cell numbers of oligotrophic and copiotrophicmicrobes fromthe sediment were enumerated by the three-tube most probable number (MPN) method using an array of nutrient-rich and oligotrophic (≈10-20mg carbon L-1) media offering simulated natural conditions of pH and salinity. A total of 50 strains from 15 different genera and 30 different species were isolated from the highest positive dilutions of MPN to identify the taxa of oligotrophs and copiotrophic microorganisms dominating in Lonar Lake. We did not get any true oligotrophs due to their adaptation to higher carbon levels during the isolation procedure. On the contrary, several true copiotrophs, which could not adapt and survive on a low-carbonmedium, were isolated. It is also observed that changes inmedium composition and nutrient level altered the selection of organisms from the same sample. Our data indicate that copiotrophic microorganisms dominate the eutrophic Lonar Lake, which is also supported by the past metagenomics studies from the same site. We also reported that quick depletion of carbon fromoligotrophicmediumworked as a limiting factor, inducing cell death after 2-3 generations and preventing the development of visible colonies on plates and suffcient optical density in liquid medium. Therefore, a long-term supply of low levels of carbon, followed by isolation on enriched media, can serve as a good strategy in isolation of novel taxa of microorganism, with industrial or environmental importance. [ABSTRACT FROM AUTHOR]

Water resources such as rivers and oceans an indispensable resource for the living. The present investigation was carried out for biodegradation of industrial effluent by using bacterial isolates immobilized in PDMS sponges. Bacterial isolates DP4 Bacillus and DP7 Stenotrophomonas (black cotton soil of Maharashtra, India) was performed to degrade the industrial spentwash. In first experiment, effluent was added to the nutrient broth (NB) inoculated with DP4 and DP7 strains in different flasks containing PDMS sponges. DP4 strain degraded 84% of melanoidin as compared to DP7 strain, which degraded 50% melanoidin in 6 days. In second experiment, both bacterial strains were inoculated in (i) NB media (ii) immobilized in PDMS sponges, inoculated in NB media and the effluent was added. Degradation of melanoidin was determined at intervals of 24h using spectrophotometer (OD 520nm). Immobilized cells degraded melanoidin better than free cells and Bacillus DP4 showed a higher degradation rate as compared to Stenotrophomonas DP7. • Immobilized bacterial isolates were used to degrade melanoidins from spent wash. • Biodegradation efficiency of free and immobilized cells were compared. • Melanoidin degradation was improved using 'repeated addition' strategy. [ABSTRACT FROM AUTHOR]