Microbial food cultures have directly or indirectly come under various regulatory frameworks in the course of the last decades. Several of those regulatory frameworks put emphasis on "the history of use", "traditional food", or "general recognition of safety". Authoritative lists of microorganisms with a documented use in food have therefore come into high demand. One such list was published in 2002 as a result of a joint project between the International Dairy Federation (IDF) and the European Food and Feed Cultures Association (EFFCA). The "2002 IDF inventory" has become a de facto reference for food cultures in practical use. However, as the focus mainly was on commercially available dairy cultures, there was an unmet need for a list with a wider scope. We present an updated inventory of microorganisms used in food fermentations covering a wide range of food matrices (dairy, meat, fish, vegetables, legumes, cereals, beverages, and vinegar). We have also reviewed and updated the taxonomy of the microorganisms used in food fermentations in order to bring the taxonomy in agreement with the current standing in nomenclature.
An alkali-sensitive mutant, 38154, of the alkalophilic Bacillus sp. strain C-125 could not grow at an alkaline pH. The nucleotide sequence of a 3.7 kb parental DNA fragment that recovers the growth of 38154 at alkaline pH has four open reading frames (ORF1-4). By subcloning the fragment, we demonstrated that a 0.25 kb DNA region is responsible for the recovery. Direct sequencing of the mutant's corresponding region revealed a G to A substitution. The mutation resulted in an amino acid substitution from Gly-393 to Arg of the putative ORF1 product, which was deduced to be an 804-amino-acid polypeptide with a molecular weight of 89,070. The N-terminal part of the putative ORF1 product showed amino acid similarity to those of the chain-5 products of eukaryotic NADH quinone oxidoreductases. Membrane vesicles prepared from 38154 did not show membrane potential (delta psi)-driven Na+/H+ antiporter activity. Antiporter activity was resumed by introducing a parental DNA fragment which recovered the mutant's alkalophily. These results indicate that the mutation in 38154 affects, either directly or indirectly, the electrogenic Na+/H+ antiporter activity. This is the first report which shows that a gene responsible for the Na+/H+ antiporter system is important in the alkalophily of alkalophilic microorganisms.
Aims: To investigate the fate of a streptomycin–rifampicin‐resistant variant of Lactobacillus gasseri SBT2055 (LG2055SR) and the influence of its oral administration on the composition and metabolism of the intestinal microflora.
Methods and Results: Intestinal passage of LG2055SR was monitored by a combination of selection with antibiotics and identification by a randomly amplified polymorphic DNA (RAPD)‐PCR method. Composition of intestinal microflora was analysed by the method developed by Mitsuoka et al. (1965, 1974). Establishment of orally‐administered LG2055SR in the human intestine was confirmed in this study. LG2055SR ingestion specifically lowered faecal populations of Staphylococcus and faecal contents of p‐cresol.
Conclusions: LG2055SR and its parent strain, LG2055, are considered to be appropriate candidates for probiotics.
Significance and Impact of the Study: It is clarified that LG2055SR has the ability to establish in the human gastrointestinal tract and alters the composition and metabolism of the intestinal microflora and physical characteristics of faeces.
Campylobacter is a normal inhabitant of the chicken gut. Pathogenic infection with this organism in humans is accompanied by severe inflammation of the intestinal mucosal surface. The aim of this study was to evaluate the ability of Lactobacillus gasseri SBT2055 (LG2055) to inhibit the adhesion and invasion of Campylobacter jejuni in vitro and to suppress C. jejuni colonization of chicks in vivo. Pretreatment with LG2055 significantly reduced adhesion to and invasion of a human epithelial cell line, Intestine 407, by C. jejuni 81–176. Methanol (MeOH)-fixed LG2055 also reduced infection by C. jejuni 81–176. However, proteinase K (ProK)-treated LG2055 eliminated the inhibitory effects. Moreover, LG2055 co-aggregated with C. jejuni 81–176. ProK treatment prevented this co-aggregation, indicating that the co-aggregation phenotype mediated by the proteinaceous cell-surface components of LG2055 is important for reducing C. jejuni 81–176 adhesion and invasion. In an in vivo assay, oral doses of LG2055 were administered to chicks daily for 14 days after oral inoculation with C. jejuni 81–176. At 14 days post-inoculation, chicks treated with LG2055 had significantly reduced cecum colonization by C. jejuni. Reduction in the number of C. jejuni 81–176 cells adhering to and internalized by human epithelial cells demonstrated that LG2055 is an organism that effectively and competitively excludes C. jejuni 81–176. In addition, the results of the chick colonization assay suggest that treatment with LG2055 could be useful in suppressing C. jejuni colonization of the chicks at early growth stages.
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