Sudan azo dyes have genotoxic effects and ingestion of food products contaminated with Sudan I, II, III, IV, and Para Red could lead to exposure in the human gastrointestinal tract. In this study, we examined thirty-five prevalent species of human intestinal bacteria to evaluate their capacity to degrade Sudan dyes and Para Red. Among these tested bacterial strains, 23, 13, 33, 30, and 29 out of 35 species tested were able to reduce Sudan I, II, III, IV, and Para Red, respectively, to some extent. Bifidobacterium infantis, Clostridium indolis, Enterococcus faecalis, Lactobacillus rhamnosus, and Ruminococcus obeum were able to reduce completely all four tested Sudan dyes and Para Red. Escherichia coli and Peptostreptococcus magnus were the only two strains that were not able to reduce any of the tested Sudan dyes and Para Red to any significant extent. Metabolites of the reduction of the tested Sudan dyes and Para Red by E. faecalis were isolated and identified by HPLC and LC/ESI-MS analyses and compared with authentic standards. Thus it appears that the ability to reduce Sudan dyes and Para Red except Sudan II is common among bacteria in the human colon.

A polycyclic aromatic hydrocarbon (PAH)-utilizing Mycobacterium strain, PYR-1(T), was isolated from petroleum-contaminated estuarine sediments and has been shown by 16S rRNA gene sequencing to be closely related to Mycobacterium aurum ATCC 23366(T) and Mycobacterium vaccae ATCC 15438(T). In this investigation, the 16S rDNA, fatty acid methyl esters, DNA-DNA hybridization, PFGE analysis of restriction-digested total genomic DNA and biochemical tests were used to determine the taxonomic relationship of strain PYR-1(T) to other closely related Mycobacterium species. The sequence of the 16S rRNA gene of strain PYR-1(T) was similar to that of Mycobacterium austroafricanum ATCC 33464(T), except for one gap at position 43. Fatty acid methyl ester analysis also showed similarity to M. austroafricanum ATCC 33464(T); however, the Euclidean distance was greater than 4.0, indicating that these strains were not identical. Dot-blot DNA-DNA hybridization of strain PYR-1(T) with M. austroafricanum indicated less than 40% relatedness. When the total chromosomal DNA of M. aurum ATCC 23366(T), M. austroafricanum ATCC 33464(T) and strain PYR-1(T) was digested with restriction enzyme Xbal and analysed by PFGE, all three organisms gave different restriction patterns. Previous studies from our laboratory have shown that the reverse-phase HPLC elution profiles of mycolic acids of strain PYR-1(T) and M. austroafricanum ATCC 33464(T) have different patterns. Based on phylogenetic analysis using 165 rRNA gene sequences, fatty acid analysis, DNA-DNA hybridization and PFGE analysis and physiological and chemotaxonomic characteristics, it is concluded that strain PYR-1(T) (= DSM 7251(T) = NRRL B-24157(T)) represents a novel species of the genus Mycobacterium, for which the name Mycobacterium vanbaalenii sp. nov. is proposed.

Aims: Phenotypic and genotypic bacteria identification methods were compared for their efficacy in determining the composition of competitive exclusion (CE) products. Methods and Results: Phenotypic methods used for bacterial identification were fatty acid methyl ester profiles, biochemical assays and carbohydrate utilization profiles. Genotypic methods were MicroSeq16S rRNA sequence analysis and BLAST searches of the GenBank sequence database. Agreement between phenotypic and genotypic methods for identification of bacteria isolated from the Preempt CE product was 20%. A defined test mixture of bacteria was identified to the species level 100% by BLAST analysis, 64% by MicroSeq and 36% by phenotypic techniques. Conclusions: The wide range of facultative and obligate anaerobic bacteria present in a CE product are more accurately identified with 16S rRNA sequence analyses than with phenotypic identification techniques. Significance and Impact of the Study: These results will provide guidelines for manufacturers of CE products to submit more reliable product information for market approval by regulatory agencies.

Enterococcus casseliflavus and Enterococcus gallinarum strains resistant to metronidazole, nitrofurantoin and nitrofurazone were isolated from fecal samples of a patient with recurrent ulcerative colitis treated with metronidazole. Unlike other metronidazole-resistant bacteria, these strains produced nitroreductase but metabolized metronidazole to compounds that could not be detected by liquid chromatography with UV or mass spectral analysis. Metronidazole-susceptible Clostridium perfringens grew equally well in spent cultures of Enterococcus spp. incubated with or without metronidazole. These data indicate that the nitroreductases produced by these Enterococcus strains did not activate metronidazole to bactericidal metabolites and these bacteria may reduce the effectiveness of metronidazole. We have indirect evidence for an alternative pathway that results in metronidazole resistance. These strains of enterococcus had nitroreductase so resistance should not have occurred.