Study on biosurfactant production by marine microorganisms isolated from Vietnam coastal zones applied to environmental protection

rRNA, 26S rRNA analyses, they were defined as Hortae werneckii HL1a, Pichia ohmeri HL1b, Rhodotorula glutinis HL2a, Rhodosporidium diobovatum HL4a, Candida atlantica HL10a, Och[r]

Study on biosurfactant production by marine microorganisms isolated from Vietnam coastal zones applied to

environmental protection

Lai Thuy Hien*, Nguyen Thi Yen, Pham Thi Hang, Le Thi Nhi Cong, Vuong Thi Nga, Nguyen Thi Thu Huyen

Department of Petroleum Microbiology, Institute of Biotechnology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Hanoi, Vietnam

ABSTRACT

Biosurfactants are microbial surface active compounds with both a hydrophilic and hydrophobic regions in their structures They are grouped as glycolipid, lipolipid, phospholipid, fatty acid, neutral lipid, polymeric and particulate biosurfactants Nowadays, biosurfactant are using in different sectors such as petroleum industry, food industry, pharmaceuticals, medicine, cosmetics and environmental protection In comparison with chemically synthesized surfactants, they have plenty of advantages, including lower toxicity, higher biodegradability and better environmental compatibility Most biosurfactants are produced by bacteria, yeast and fungi during fermentation on various carbon sources (glycerol, olive oil, diesel oil, soybean oil, molasses …)

From marine water and sand samples taken from different sites on Vietnam coastal zones (Halong bay, Catba island, Nghison sea, Quinhon sea, Vungtau sea, Binhthuan sea), we isolated 20 yeast and 35 bacteria strains that are able to produce biosurfactant Amongst, we selected 36 strains that are capable of the highest biosurfactant production Their biosurfactant producing capacity with oil emulsification index (E24) was over 70% and 16 of 36 strains produced the high amount of biosurfactant, ranging from 15 - 25 g biosurfactant/l Using API kit and 16S

*

rRNA, 26S rRNA analyses, they were defined as Hortae werneckii HL1a, Pichia ohmeri HL1b, Rhodotorula glutinis HL2a, Rhodosporidium diobovatum HL4a, Candida atlantica HL10a, Ochrobactrum cytisis CB1c1, Bacillus megatherium CB1c2, Janibacter marinus CB2a, Candida parapsilosis CB5a, Rhodosporidium sphaerocarpum CB7a, Acinetobacter haemolyticus NS5a, Acinetobacter calcoaceticus QN15, Rhodotorula mucilaginosa VT08, Candida tropicalis VT09, Aeromonas sobria H1, Pseudomonas pseudomalei H24, Pseudomonas aeruginosa H33, Bacillus subtilis N1, Acinetobacter junii 6C1, Leuconostoc sp 6C3… Biosurfactants produced by selected

marine bacteria and yeasts stimulated the growth of oil - degrading microbial population and

total oil quantity reduced for 81% after five experimental days Especially, biosurfactants

produced by Rhodotorula mucilaginosa VT08 and Candida tropicalis VT09 strains showed a great potential for environmental protection because of their non-toxicity The results suggested