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PubMed | a Yakult Central Institute for Microbiological Research
Type: Journal Article | Journal: Bioscience, biotechnology, and biochemistry | Year: 2016

In a study of genetic lesions responsible for amino acid requirements in multiple auxotrophic lactic acid bacteria, a systematic attempt was made to isolate mutants that could synthesize each of the amino acids required by the parental strains of Lactococcus lactis, Enterococcus faecium, and Pediococcus acidilactici. After treatment with appropriate mutagens or, in some cases, spontaneously, such mutants could indeed be obtained with respect to many but not all essential amino acids. Successful isolation of mutants for a given amino acid means that a minor genetic lesion reparable by single-step mutations affects its biosynthesis; a failure to isolate mutants suggests the involvement of more extensive lesions. Analysis of the results obtained showed certain regularities: some of the biosynthetic pathways for individual amino acids were virtually unaffected or affected by minor lesions in all the strains tested, while others were affected to varying extents among the different strains. Further studies showed that the ability to synthesize a number of amino acids had been acquired simultaneously in several of the amino acid-synthesizing mutants obtained after a single-step mutagenesis in E. faecium and P. acidilactici. Some detailed analysis with one of such mutants from E. faecium showed that a structural alteration of RNA polymerase caused by a single-step mutation is to some extent associated with simultaneous acquisition of the synthetic ability for a number of amino acids.


PubMed | a Yakult Central Institute for Microbiological Research
Type: Journal Article | Journal: Bioscience, biotechnology, and biochemistry | Year: 2014

Galacto-oligosaccharides (GOSs) are recognized as prebiotics beneficial to human health through their abilities to modulate gut microbiota. On the other hand, it has been reported that immediate allergic reactions are caused by a GOS product (Bc-GOS) produced by treating lactose with -galactosidase derived from Bacillus circulans. The objective of this study was to create a safer GOS product that is less likely to cause GOS-induced allergy (GOS-AL). First, we identified two derivatives of tetrasaccharide sugar chains in Bc-GOS as the factors responsible for GOS-AL by histamine release test (HRT) using blood samples obtained from two GOS-AL patients. Through our search for non-allergic GOS, we developed a new GOS product, SK-GOS, which was produced by catalyzing lactose with -galactosidase derived from Sporobolomyces singularis and Kluyveromyces lactis. We regard it as a hypoallergic and safe GOS product that does not cause GOS-AL.

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