An application of wastewater treatment in a cold environment and stable lipase production of Antarctic basidiomycetous yeast Mrakia blollopis.

• Published in: PLoS ONE
• Main Authors: Masaharu Tsuji, Yuji Yokota, Kodai Shimohara, Sakae Kudoh, Tamotsu Hoshino
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science (PLoS) 2013
• Subjects: Medicine; R; Science; Q; Antarctic; East Antarctica; Skarvsnes; Naga Ike; Antarc*; Antarctica
• Online Access: https://doi.org/10.1371/journal.pone.0059376; https://doaj.org/article/cb50127db4694d91b843b367099cda64

Milk fat curdle in sewage is one of the refractory materials for active sludge treatment under low temperature conditions. For the purpose of solving this problem by using a bio-remediation agent, we screened Antarctic yeasts and isolated SK-4 strain from algal mat of sediments of Naga-ike, a lake in Skarvsnes, East Antarctica. The yeast strain showed high nucleotide sequence homologies (>99.6%) to Mrakia blollopis CBS8921(T) in ITS and D1/D2 sequences and had two unique characteristics when applied on an active sludge; i.e., it showed a potential to use various carbon sources and to grow under vitamin-free conditions. Indeed, it showed a biochemical oxygen demand (BOD) removal rate that was 1.25-fold higher than that of the control. We considered that the improved BOD removal rate by applying SK-4 strain was based on its lipase activity and characteristics. Finally, we purified the lipase from SK-4 and found that the enzyme was quite stable under wide ranges of temperatures and pH, even in the presence of various metal ions and organic solvents. SK-4, therefore, is a promising bio-remediation agent for cleaning up unwanted milk fat curdles from dairy milk wastewater under low temperature conditions.