title: An application of wastewater treatment in a cold environment and stable lipase production of Antarctic basidiomycetous yeast Mrakia blollopis.
abstract: 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.
authors.affiliation: Biomass Refinery Research Center (BRRC), National Institute of Advanced Industrial Science and Technology (AIST), Kagamiyama, Higashihiroshima, Hiroshima, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Tsuji
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yokota
authors.forename: Kodai
authors.initials: K
authors.lastname: Shimohara
authors.forename: Sakae
authors.initials: S
authors.lastname: Kudoh
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Hoshino
mesh_terms: D000864:Antarctic Regions; D001487:Basidiomycota / Q000201:enzymology* / Q000302:isolation & purification; D001673:Biodegradation, Environmental; D003080:Cold Temperature; D008049:Lipase / Q000378:metabolism*; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000382:microbiology*
chemical_list: D008049:Lipase; D062065:Wastewater