Evaluation of marine microorganisms for characteristic presence of novel biomolecules

摘要

Marine bacteria are an important and relatively unexplored resource for novel microbial products such as drugs, chemicals, different types of useful lipids, enzymes of unusual resistance etc. In the present work, eight different bacterial cultures from different marine samples (two from the Indian Ocean and four from Antarctica) have been isolated and screened for the presence of bioactive compounds such as industrial enzymes (amylase and lipase), exopolysaccharides (EPS), biosurfactant and intracellular lipid granules. Interestingly, five out of eight isolates produced multiple compounds of industrial importance. All the cultures (i) were Gram negative rods, (ii) showed optimum pH of 7- 8, (iii) grew well at 30 °C and (iv) tolerated NaCl upto 25%. Three of them were catalase positive and citrate was used as carbon source by five of them. MBRI 2 and BRI 27 were amylase positive while BRI 11, BRI 13, BRI 28 and BRI 29 were lipase positive. MBRI 2 was the only isolate which showed positive result when screened for EPS using YMG agar. Six isolates viz. MBRI 2, BRI 11, BRI 13, BRI 16, BRI 27 and BRI 29 were able to produce biosurfactant as observed in drop collapsing test. MBRI 2 and BRI 29 showed presence of intracellular lipid granules in Sudan Black B staining. In the light of our observations, bacterial isolates from marine samples are novel sources of industrial enzymes and other bioactive compounds, capable of producing them at high salt concentration. Moreover, research on the interactive effects of salt concentration, pH and temperature will be useful to understand their true potentialities for industrial applications.