Screening for industrially important enzymes from thermophilic bacteria; selection of lipase-producing microorganisms and optimization of culture conditions
Zehra Burcu Bakir, Kubilay Metin
In this study, 201 thermophilic bacteria that were isolated from natural hot springs in Aydin/Turkey and registered in Adnan Menderes University Department of Biology culture stocks were used. It was determined that 43 of these bacteria exhibited lipolytic activity and 22 of them exhibited lipase activity. These 22 lipase positive isolates were grown in LB broth medium and the quantitative lipase activities were determined. HBB 134 was chosen as the best lipase producing isolate with the activity of 19.925 U/mL. According to 16S rRNA sequences, it was found that the isolate showed maximum similarity (% 99) with Anoxybacillus flavithermus. The best enzyme production from HBB 134 was determined in medium including 0.5% olive oil as carbon source and 0.5% pepton as nitrogen source, pH 6.50 and 45 °C. When the isolate HBB 134 was grown in optimum culture conditions it was determined that production of the lipase started at the beginning of the logarithmic growth phase and it reached maximum level in the middle (12 hour) of the logarithmic phase. It was determined that most of the enzyme activity was intracellular.