eWe report the complete genome sequence of Lactococcus lactis IO-1 ‫؍(‬ JCM7638). It is a nondairy lactic acid bacterium, produces nisin Z, ferments xylose, and produces predominantly L-lactic acid at high xylose concentrations. From ortholog analysis with other five L. lactis strains, IO-1 was identified as L. lactis subsp. lactis.

Enterococcus mundtii QU 25, a non-dairy bacterial strain of ovine faecal origin, can ferment both cellobiose and xylose to produce l-lactic acid. The use of this strain is highly desirable for economical l-lactate production from renewable biomass substrates. Genome sequence determination is necessary for the genetic improvement of this strain. We report the complete genome sequence of strain QU 25, primarily determined using Pacific Biosciences sequencing technology. The E. mundtii QU 25 genome comprises a 3 022 186-bp single circular chromosome (GC content, 38.6%) and five circular plasmids: pQY182, pQY082, pQY039, pQY024, and pQY003. In all, 2900 protein-coding sequences, 63 tRNA genes, and 6 rRNA operons were predicted in the QU 25 chromosome. Plasmid pQY024 harbours genes for mundticin production. We found that strain QU 25 produces a bacteriocin, suggesting that mundticin-encoded genes on plasmid pQY024 were functional. For lactic acid fermentation, two gene clusters were identified—one involved in the initial metabolism of xylose and uptake of pentose and the second containing genes for the pentose phosphate pathway and uptake of related sugars. This is the first complete genome sequence of an E. mundtii strain. The data provide insights into lactate production in this bacterium and its evolution among enterococci.

The inhibitory effects of human-derived Bifidobacterium longum BB536 on harmful intestinal bacteria were examined by co-cultivation of BB536 with each one of the following eight bacterial strains: Escherichia coli, Klebsiella pneumoniae, Clostridium clostridiiforme, C. perfringens, Bacteroides distasonis, B. fragilis, B. thetaiotaomicron and B. vulgatus. In comparison with the results of mono-cultivation, BB536 inhibited both the growth of these putrefactive bacteria and their production of ammonia, and decreased the pH of the culture medium by producing lactic and acetic acids. Enzymatic assays showed that in BB536 the sorts of the enzymes involved in ammonia production (urease and amino acid deaminases) were rather few and their activities were weaker than observed in the harmful bacteria, whereas the activities of enzymes involved in ammonia assimilation (glutamine synthetase, glutamate synthase and glutamate dehydrogenase) were much higher in BB536 than in the putrefactive bacteria.

In the xylose and/or glucose utilization by QU 25,the transcriptional regulation of related genes is involved in the catabolite repression,not in the metabolic shift between homo- and hetero-lactic fermentations.

Lactococcus lactis IO-1 (JCM7638) produces L-lactic acid predominantly when grown at high xylose concentrations, and its utilization is highly desired in the green plastics industry. Therefore it is worthwhile studying its genomic traits. In this study, we focused on (i) genes of possible horizontal transfer derivation (prophages, the nisin-sucrose transposon, and several restrictionmodification systems), and (ii) genes for the synthetic pathways of amino acids and vitamins in the IO-1 genome. In view of the results of this analysis, we consider their meanings in strain IO-1.