Diversity of predominant lactic acid bacteria associated with cocoa fermentation in Nigeria.

The fermentation of cocoa relies on a complex succession of bacteria and filamentous fungi, all of which can have an impact on cocoa flavor. So far, few investigations have focused on the diversity of lactic acid bacteria involved in cocoa fermentation, and many earlier investigations did not rely on polyphasic taxonomical approaches, which take both phenotypic and genotypic characterization techniques into account. In our study, we characterized predominant lactic acid bacteria from cocoa fermentations in Nigeria, using a combination of phenotypic tests, repetitive extragenic palindromic PCR, and sequencing of the 16S rRNA gene of representative strains for accurate species identification.

Lactobacillus ghanensis sp. nov., a motile lactic acid bacterium isolated from Ghanaian cocoa fermentations.

Three Gram-positive, catalase-negative, motile, rod-shaped strains, designated L486, L489(T) and L499, were isolated from fermenting cocoa. These organisms produced DL-lactic acid from glucose without gas formation. Ammonia was not produced from arginine.

Diversity of enterococcal bacteriocins and their grouping in a new classification scheme.

Enterococci are lactic acid bacteria of importance in food, public health and medical microbiology. Many strains produce bacteriocins, some of which have been well characterized. This review describes the structural and genetic characteristics of enterocins, the bacteriocins produced by enterococci.

Comparison of two chromogenic media for the detection of Listeria monocytogenes with the plating media recommended by EN/DIN 11290-1.

The efficacy of two selective chromogenic culture media, Agar Listeria Ottaviani and Agosti (ALOA) and RAPID' L. mono for the detection of Listeria monocytogenes in food, was compared with that of an official culture method according to the EN/DIN 11290-01 and -02 protocols [corresponding to the section 35 LMBG (German Food Act) method]. A total of 310 pre-packed ready-to-eat food samples (100 of graved and cold smoked salmon, 130 of different raw and cooked sausages and 80 of delicatessen and mixed salads) were examined.

Lactobacillus spp. with in vitro probiotic properties from human faeces and traditional fermented products.

Lactobacillus strains from traditional African fermented milk products, as well as human intestinal isolates were identified and investigated in vitro for their technological and functional characteristics as potential new probiotic strains. To test survival under gastrointestinal conditions, first the protective effect of milk and the effects of medium composition, lysozyme, pepsin, and pH of the medium on bacterial viability were assessed in vitro using the Plackett-Burman statistical model and the commercially used L. johnsonii LA1 probiotic strain.

Pediococcus stilesii sp. nov., isolated from maize grains.

A Gram-positive, coccus-shaped, lactic acid bacterium, strain LMG 23082T, was isolated from steeped maize grains. The organism is homofermentative and produces D- and L-lactic acid from glucose. 16S rRNA gene sequence analysis revealed that the organism belongs to the genus Pediococcus, with Pediococcus pentosaceus and Pediococcus acidilactici as nearest neighbours.

Lactobacillus arizonensis is a later heterotypic synonym of Lactobacillus plantarum.

The 'Lactobacillus plantarum group' encompasses the taxa Lactobacillus plantarum subsp. plantarum, Lactobacillus plantarum subsp. argentoratensis, Lactobacillus paraplantarum, Lactobacillus pentosus and Lactobacillus arizonensis.

Lactobacillus curvatus subsp. melibiosus is a later synonym of Lactobacillus sakei subsp. carnosus.

On the basis of phenotypic and DNA-DNA reassociation studies, strain CCUG 34545T has been considered to represent a distinct Lactobacillus curvatus subspecies, Lactobacillus curvatus subsp. melibiosus. However, in several independent studies dealing with Lactobacillus sakei and L.

Characterization of Penicillium roqueforti strains used as cheese starter cultures by RAPD typing.

Seventy-six strains of Penicillium roqueforti used as starter cultures for mould ripened blue cheeses have been analysed for their RAPD genotype by using three different primers. A comparison of the RAPD patterns within each primer group revealed that the genetic constitution of the strains was similar, as most of the strains showed very similar overall patterns. Despite these similarities with each primer, distinct RAPD genotype groups could be identified.

Antagonistic activity of the food-related filamentous fungus Penicillium nalgiovense by the production of penicillin.

Defined strains of the genus Penicillium used as starter cultures for food and strains isolated from mold-fermented foods were analyzed for their ability to inhibit the growth of Micrococcus luteus DSM 348 used as an indicator organism. Most of the strains belonging to the species Penicillium nalgiovense showed antagonistic activity in agar diffusion assays. Penicillium camemberti and Penicillium roqueforti strains proved to be inactive in these tests.

Comparative studies on cytotoxic and genotoxic effects of two organic mercury compounds in lymphocytes and gastric mucosa cells of Sprague-Dawley rats.

Human lymphocytes (HL) as well as lymphocytes (RL), hepatocytes (RH), and gastric mucosa cells (GM) of Sprague-Dawley rats were treated in vitro for 1 h with methylmercury chloride (MMC, 0.5-4 micrograms/ml) and dimethylmercury (DMM, 5-40 micrograms/ml). The cytotoxicity of the two organic mercury compounds was assessed by dye exclusion, and the extent of induced DNA fragmentation was measured with a single-cell microgel electrophoresis assay.

Systemic genotoxic effects of tobacco-related nitrosamines following oral and inhalational administration to Sprague-Dawley rats.

An ex vivo model to detect nonspecific DNA damage in different rat tissues has been developed and employed to study systemic properties of tobacco-specific N-nitrosamines. One hour after treatment of rats with the carcinogens, primary, intact cells were isolated from various organs. Viability of the cells was monitored by trypan blue exclusion.