23:T456,Ochratoxin A (OTA) is a well-known, natural contaminant in foods and feeds because of its toxic effects, such as nephrotoxicity in various animals. Recent studies have revealed that Alcaligenes faecalis could generate enzymes to efficiently degrade OTA to ochratoxin α (OTα) in vitro. In an effort to obtain the OTA degrading mechanism, we purified and identified a novel degrading enzyme, N-acyl-L-amino acid amidohydrolase (AfOTase), from A. faecalis DSM 16503 via mass spectrometry. The same gene of the enzyme was also encountered in other A. faecalis strains. AfOTase belongs to peptidase family M20 and contains metal ions at the active site. In this study, recombination AfOTase was expressed and characterized in Escherichia coli. The molecular mass of recombinant rAfOTase was approximately 47.0 kDa, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme exhibited a wide temperature range (30-70 °C) and pH adaptation (4.5-9.0) and the optimal temperature and pH were 50 °C and 6.5, respectively.24:T429,An extremely thermostable xylanase gene, xynB, from hyperthermophilic bacterium Thermotoga maritima MSB8 was successful expressed in Kluyveromyces lactis. Response surface methodology (RSM) was applied to optimize medium components for production of XynB secreted by the recombinant K. lactis. Secretion level (102 mg/L) and enzyme activity (49 U/ml) of XynB in the optimized medium (yeast extract, lactose, and urea; YLU) were much higher than those (56 mg/L, 16 U/ml) in original medium (yeast extract, lactose, and peptone; YLP). It was also observed that the secretory efficiency of mature XynB was improved by the YLU medium. mRNA levels of 13 characterized secretion-related genes between K. lactis cultured in YLP and YLU were detected using semi-quantitative RT-PCR method. It was found that unfolded protein response (UPR) related genes such as ero1, hac1, and kar2 were up-regulated in K. lactis cultured in YLU. Therefore, nutrient ingredient, especially nitrogen source had a significant influence on the XynB secretory efficiency in the host K. lactis.

#	Concept	H-Index	Publications	Citations
1	Engineering	2	2	99
2	Biochemistry	2	2	99
3	Medicine	1	1	44
4	Biology	1	1	44
5	Biomolecular Engineering	1	1	73

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