Study on phenol biodegradation of the bacterial strain DX3 isolated from wastewater collected in petroleum storage tanks in Do Xa, Hanoi

Abstract

Recently, universal and domestic scientists have been  interested in the handling of phenol according to biodegradable methods. The bacterial strain DX3 was  isolated from wastewater samples collected in Do Xa petroleum warehouse in Thuong Tin district, Hanoi city after triplicate  enrichments in liquid mineral salt medium Gost supplemented with 50 mg/l phenol. Colonies of the DX3 with 1.5 mm to 2 mm in diameter were milky white, round, and mucilaginous but did not root in agar. The observation of DX3 cell morphology by SEM showed a rod shape  of 1.14-2.67 mm. The bacterium was round, smooth with thin membrane, short flagellum around. Based on the morphological characteristics and sequence alignment of 16S rRNA encoding gene, strain DX3 was identified to have a high sequence homology up to 99% with Bacillus megaterium IAM 13418 and then named  Bacillus sp. DX3. This sequence was submitted to the GenBank with Accession Number KC845545. This strain was able to biodegrade 99.95% of total phenol with the initial concentration of 150 mg/l in the medium after 7 days of cultivation at 30^oC. From  these obtained results, the Bacillus sp. DX3 has contributed to enriching the number of bacteria of the genus Bacillus in particular and  microorganisms in general which are capable of highly decomposing phenol from oil contaminated wastewater  to develop phenol biodegradable technology.