Rapid detection of total bacteria in foods using a poly--lysine-based lateral-flow assay.

Food safety and freshness are evaluated according to microbiological load. To analyze this load rapidly, a poly--lysine-based lateral-flow assay (PLFA) was developed. A total of 90 strains of bacteria that are often detected in spoiled foods, including Enterobacteriaceae, lactic acid bacteria, Pseudomonas, and Bacillus were detected using the PLFA.

Rapid detection of coliform bacteria using a lateral flow test strip assay.

Coliform bacteria in foods are enumerated at food processing plants and are used as sanitary and quality indicators. To detect coliform bacteria rapidly, seven Lateral Flow Test Strips (LFTSs) that can detect the genera Aeromonas, Citrobacter, Enterobacter, Hafnia, Klebsiella/Raoultella, Pantoea and Serratia were developed. For 55 tested food isolates, the detection rate of each individual LFTS assay was only 38% to 76%, but the detection rate of the 7 combined assays was 100%.

Rapid detection of Klebsiella pneumoniae, Klebsiella oxytoca, Raoultella ornithinolytica and other related bacteria in food by lateral-flow test strip immunoassays.

Bacteria of the genera Klebsiella and Raoultella, which are present in foods and the natural environment, are associated with health hazards in humans. In the present study, two types of strips-based methods were developed to detect these bacteria simply and quickly. One method used lateral-flow test strips (LFTS) in combination with anti-Klebsiella antibodies labeled with palladium nanoparticles that bind to target bacteria, allowing their visualization.

Oceanobacillus soja sp. nov. isolated from soy sauce production equipment in Japan.

A Gram-positive, spore-forming, motile rod-shaped bacterium, designated strain Y27T, was isolated from the bottom of a mold fermenter used in the process of soy sauce production. Phylogenetic analysis of the 16S rRNA gene sequence from this strain placed it within the genus Oceanobacillus, and further sequence analysis revealed that this strain has a sequence similarity of 95.0-98.

Sporosarcina luteola sp. nov. isolated from soy sauce production equipment in Japan.

A Gram-variable, spore-forming, motile rod, designated strain Y1T, was isolated from the hopper surface of equipment used for soy sauce production. Phylogenetic analysis based on 16S rRNA gene sequence revealed that Y1T is affiliated phylogenetically to the genus Sporosarcina, and the strain showed sequence similarities of 95.8-99.

Tracing the contamination origin of coliform bacteria in two small food-processing factories.

The objective of this study was to trace contamination sources of coliform bacteria by comparing the types of coliforms between food samples and the processing environments in two small food-processing factories (factories A and B). Fermentation tests of five sugars enabled the successful classification of 16 representative type strains into eight distinct groups. The grouping procedure was then applied to comparison of the coliform flora between food products and various locations in their processing environments.

Rapid determination of multi-locus sequence types of Listeria monocytogenes by microtemperature-gradient gel electrophoresis.

This report presents a new method for identifying multi-locus sequence types of Listeria monocytogenes by microtemperature-gradient gel electrophoresis (mu-TGGE). Genomic comparison of L. monocytogenes serovar 1/2a strains EGD-e and F6854 allowed selection of novel polymorphic sequences lmo0386 and lmo0428 as optimum regions for mu-TGGE analysis, in addition to the previously identified lmo0297 gene.

Development of innovative pediocin PA-1 by DNA shuffling among class IIa bacteriocins.

Pediocin PA-1 is a member of the class IIa bacteriocins, which show antimicrobial effects against lactic acid bacteria. To develop an improved version of pediocin PA-1, reciprocal chimeras between pediocin PA-1 and enterocin A, another class IIa bacteriocin, were constructed. Chimera EP, which consisted of the C-terminal half of pediocin PA-1 fused to the N-terminal half of enterocin A, showed increased activity against a strain of Leuconostoc lactis isolated from a sour-spoiled dairy product.

Rapid discrimination of Listeria monocytogenes strains by microtemperature gradient gel electrophoresis.

Microtemperature gradient gel electrophoresis (mu-TGGE) was examined for use for the rapid subtyping of Listeria monocytogenes strains. Comparison of genomes between L. monocytogenes strains F2365 and H7858 identified a sequence encoding a portion of the PRT/PTS system IIA 2 protein domain as appropriate for mu-TGGE analysis.

Determination of essential and variable residues in pediocin PA-1 by NNK scanning.

Pediocin PA-1 is an antimicrobial peptide (called bacteriocin) that shows inhibitory activity against the food-borne pathogen Listeria monocytogenes. To elucidate which residue(s) is responsible for this function, the antimicrobial activities of pediocin PA-1 mutants were evaluated and compared. Each of the 44 native codons was replaced with the NNK triplet oligonucleotide in a technique termed NNK scanning, and 35 mutations at each position were examined for antimicrobial activities using a modified colony overlay screening method.

Rapid identification of pickle yeasts by fluorescent PCR and microtemperature-gradient gel electrophoresis.

Monitoring the yeast populations within pickle soaking fluid is imperative for ensuring optimum taste, but these analyses have proven time-consuming and expensive, limiting their industrial application. Here, yeasts were identified in the soaking fluid from Japanese radish pickles using fluorescent PCR amplification of the variable D1/D2 region of the 26S rDNA, followed by analysis with microtemperature-gradient gel electrophoresis (micro-TGGE). This smaller version of the normal TGGE apparatus is capable of analyzing samples 10- to 20-fold faster without sacrificing data quality.