2013 International Conference on Agricultural and Natural Resources Engineering Biochemical Characterization and 16S rDNA Sequencing of Lipolytic Thermophiles from Selayang Hot Spring, Malaysia

摘要

Thermophiles are well known as organisms that can withstand extreme temperature. Thermoenzymes from thermophiles have numerous potential for biotechnological applications due to their integral stability to tolerate extreme pH and elevated temperature. Because of the industrial importance of lipases, there is ongoing interest in the isolation of new bacterial strain producing lipases. Six isolates of lipases producing thermophiles namely K7S1T53D5, K7S1T53D6, K7S1T53D11, K7S1T53D12, K7S2T51D14 and K7S2T51D19 were isolated from the Selayang Hot Spring, Malaysia. The sampling site is neutral in pH with a highest recorded temperature of 53 °C. For the screening and isolation of lipolytic thermopiles, selective medium containing Tween 80 was used. Thermostability and the ability to degrade the substrate even at higher temperature was proved and determined by incubation of the positive isolates at temperature 53°C. Colonies with circular borders, convex in elevation with an entire margin and opaque were obtained. 16S rDNA gene amplification and sequence analysis were done for bacterial identification. The isolate of K7S1T53D6 was derived of genus Bacillus that is the spore forming type, rod shaped, aerobic, with the ability to degrade lipid. Meanwhile, isolates K7S1T53D5, K7S1T53D11, K7S1T53D12, K7S2T51D14 and K71S2T51D19 were derived of the genus Brevibacillus. These isolates are capable of producing lipases. Sequence alignment done through NCBI BLASTn, shows that isolate K7S1T53D6 shared the highest similarities with Bacillus sonorensis with a 97% score. Meanwhile, isolates K7S1T53D5, K7S1T53D11, K7S1T53D12, K7S2T51D14 and K7S2T51D19 shared the highest similarities with Brevibacillus borstelensis with 98% score. In conclusion, it can be established that the isolates derived from two genuses, which are the Brevibacillus and Bacillus with 93% to 98% sequence homology.