Highly enantioselective oxidation of racemic phenyl-1,2-ethanediol to optically pure (R)-(-)-mandelic acid by a newly isolated Brevibacterium lutescens CCZU12-1.

Enantioselective oxidation of racemic phenyl-1,2-ethanediol into (R)-(-)-mandelic acid by a newly isolated Brevibacterium lutescens CCZU12-1 was demonstrated. It was found that optically active (R)-(-)-mandelic acid (e.e.p > 99.9 %) is produced leaving the other enantiomer (S)-(+)-phenyl-1,2-ethanediol intact. Using fed-batch method, a total of 172.9 mM (R)-(-)-mandelic acid accumulated in the reaction mixture after the seventh feed. Moreover, oxidation of phenyl-1,2-ethanediol using calcium alginate-entrapped resting cells was carried out in the aqueous system, and efficient biocatalyst recycling was achieved as a result of cell immobilization in calcium alginate, with a product-to-biocatalyst ratio of 27.94 g (R)-(-)-mandelic acid g⁻¹ dry cell weight cell after 16 cycles of repeated use.

Enzymatic saccharification of sugarcane bagasse by N-methylmorpholine-N-oxide-tolerant cellulase from a newly isolated Galactomyces sp. CCZU11-1.

Based on the enrichment culture strategy, a novel N-methylmorpholine-N-oxide (NMMO)-tolerant cellulase-producing strain Galactomyces sp. CCZU11-1 was isolated from soil samples. After the optimization of culture condition, the highest FPA (13.4 U/mL) and CMCase (24.5 U/mL) were obtained. In both culture and reaction media containing NMMO 25% (w/v), the cellulase from Galactomyces sp. CCZU11-1 still had good activity. Furthermore, high saccharification rate was obtained in aqueous-NMMO media. Moreover, the fermentability of the hydrolyzates, obtained after enzymatic in situ saccharification of the NMMO-pretreated sugarcane bagasse, was evaluated using Saccharomyce scerevisiae. In conclusion, Galactomyces sp. CCZU11-1 is a promising candidate as high NMMO-tolerant cellulase producer and has potential application in future.