Comparison of physiological characteristics of <i>Mrakia blollopis</i> SK-4 and other <i>Mrakia</i> species.

<p>Main physiology test results for characteristics of <i>M. blollopis</i> SK-4 and related species are shown. Physiological data were taken from Fell et al. (1969), Xin and Zhou (2007), Thomas-Hall et al. (2010) and this study. +, positive; w, weak; −, negative; v, variable; nd, no data.</p

Purification of lipase from <i>Mrakia blollopis</i> SK-4.

<p>Purification of lipase from <i>Mrakia blollopis</i> SK-4.</p

Substrate specificity of lipase form <i>Mrakia blollopis</i> SK-4.

<p>Substrates were p-nitrophenyl esters. Relative activity for each substrate (▪) is expressed as the percentage of activity toward p-nitrophenyl-palmitate (□).</p

Comparison of the effects of various metal ions, EDTA and various organic solvents on <i>M. blollops</i> SK-4 and <i>Cryptococcus</i> sp. S-2 lipase activity.

<p>Comparison of the effects of various metal ions, EDTA and various organic solvents on <i>M. blollops</i> SK-4 and <i>Cryptococcus</i> sp. S-2 lipase activity.</p

Effects of temperature and pH on SK-4 lipase.

<p>(A) Effects of temperature on lipase activity (○) and thermostability of the lipase (•). For effect of temperature, lipase activity assay was performed at various temperatures in 50 mM sodium phosphate buffer (pH 7.0) for 30 min. For thermostability, lipase was preincubated at various temperatures for 30 min. Remaining lipase activity was examined at 65°C for 30 min in 50 mM Tris-HCl buffer (pH 8.5). The line was fitted by using the Eyring-Arrhenius equation. (B) Effects of pH on lipase activity (○) and pH stability of lipase (•). For effect of pH, lipase activity assay was performed with various buffers at 30°C for 30 min using p-nitrophenyl-palmitate as a substrate. For pH stability, lipase was preincubated in various pH buffers at 30°C for 15 h and then pH of the buffer was adjusted to 8.5. The remaining enzyme activity was examined at 65°C for 30 min using p-nitrophenyl-palmitate as a substrate. The line was fitted by Henderson- Hasselbalch equation.</p

Phylogenetic tree of <i>Mrakia blollopis</i> SK-4 and related species.

<p>(A) Maximum parsimony analysis of the D1/D2 domain of the 26 rRNA gene sequence. Bootstrap percentages from 1000 replications are shown on the branches. <i>Mrakiella cryoconiti</i> CBS 10834^T and <i>Mrakiella cryoconiti</i> CBS 10835 were used as an out group. (B) Neighbor-joining tree of the ITS region containing the 5.8 S rRNA gene sequence. Bootstrap percentages from 1000 replications are shown on the branches. <i>Mrakiella aquatica</i> DBVPG4994 and <i>Mrakiella aquatica</i> DBVPG4990 were used as an out group.</p

Performance of activated sludge system treating model milking parlor wastewater.

<p>(A) Results of measurement of initial BOD and final BOD. (B) Effect of BOD removal rate by ASM treatment. (0.35AS) for 0.35 BOD loading rate of model parlor wastewater treated by activated sludge (control), (0.35ASM) for 0.35 BOD loading rate of model parlor wastewater treated by activated sludge containing <i>M. blollopis</i> SK-4, (0.52AS) for 0.52 BOD loading rate of model parlor wastewater treated by activated sludge (control) and (0.52ASM) for 0.52 BOD loading rate of model parlor wastewater treated by activated sludge containing <i>M. blollopis</i> SK-4. Abbrebiations for <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059376#pone-0059376-g003" target="_blank">Figure 3</a> are biochemical oxygen demand (BOD), activated sludge (AS) and activated sludge containing <i>Mrakia blollopis</i> SK-4 (ASM).</p

An Application of Wastewater Treatment in a Cold Environment and Stable Lipase Production of Antarctic Basidiomycetous Yeast <em>Mrakia blollopis</em>

<div><p>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 <i>Mrakia blollopis</i> 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.</p> </div

Comparison of <i>Mrakia blollopis</i> SK-4 lipase characteristics with other yeast lipase characteristics.

<p>Comparison of <i>Mrakia blollopis</i> SK-4 lipase characteristics with other yeast lipase characteristics.</p