Proteolytic heterotrophic bacteria of cyanobacterial assemblage from Schirmacher oasis, Antarctica, capable of growing under extreme conditions

摘要

Physiologically diverse groups of bacteria were isolated from cyanobacterial assemblages of Schirmacher oasis Antarctica. Psychrotrophs have been the most dominant, with little population of thermo-tolerant and halo-tolerant bacteria. One-third of the isolates showed pigmentation, which has been temperature-dependent in thermo-tolerant strains. Almost half of the isolates produced extracellular proteases depending on temperature, pH or salt concentration. Isolates also produced other hydrolytic enzymes, e.g. urease, phosphatase, lipase, etc. Two isolates showed multiple antibiotic resistance; however one halo-tolerant has been sensitive to all the antibiotics tested. Isolates preferred different protein and carbohydrate sources for growth, and in most of the cases protease was maximally induced in the presence of glucose/lactose. The effect of temperature and pH on growth, and enzyme production and activity have also been studied.