The accumulation of lactate in the growth medium does, however, inhibit growth and limits the yield from batch and fed-batch processes. We therefore combined the P170 expression system with the REED™ technology, learn more which allows control of lactate concentration by electro-dialysis during fermentation. Using this combination, production of the Staphylococcus aureus nuclease reached 2.5 g L−1. “
“In this study, we developed
a toolbox for genetic manipulation of Lactobacillus diolivorans, a promising production organism for 1,3-propanediol from glycerol. Two major findings play a key role for successful transformation of this organism: (1) the absence of a native plasmid, because a native plasmid is a major obstacle for transformation of L. diolivorans, and (2) the absence of DNA methylation. A suitable expression plasmid, pSHM, for homologous and heterologous protein expression in L. diolivorans was constructed. This plasmid is based on the replication origin repA of L. diolivorans. The native glyceraldehyde-3-phosphate dehydrogenase promoter is used for constitutive expression of the genes of interest. Functional expression of genes in L. diolivorans
was shown with two examples: production of green fluorescent protein resulted in a 40- to 60-fold higher fluorescence of the obtained clones compared with the wild-type strain. Finally, the homologous overexpression selleck products of a putatively NADPH-dependent 1,3-propanediol oxidoreductase improved 1,3-propanediol production by 20% in batch cultures. “
“Nonspoiled food that nevertheless contains bacterial pathogens constitutes a much more serious health problem than spoiled food, as the consumer is not warned beforehand. However, data
on the diversity of bacterial species in meat juice are rare. To study the bacterial load of fresh pork from ten different distributors, we applied a combination of the conventional culture-based and molecular methods for detecting and quantifying the microbial spectrum of fresh pork meat juice samples. Altogether, we identified 23 bacterial species of ten different families analyzed by 16S rRNA BCKDHA gene sequencing. The majority of isolates were belonging to the typical spoilage bacterial population of lactic acid bacteria (LAB), Enterococcaceae, and Pseudomonadaceae. Several additional isolates were identified as Staphylococcus spp. and Bacillus spp. originating from human and animal skin and other environmental niches including plants, soil, and water. Carnobacterium divergens, a LAB contributing to the spoilage of raw meat even at refrigeration temperature, was the most frequently isolated species in our study (5/10) with a bacterial load of 103–107 CFU mL−1.