Polyphasic taxonomic characterization of lactic acid bacteria isolated from spontaneous sorghum fermentations used to produce ting, a traditional South African food

Ting, an indigenous cooked fermented food made from sorghum flour, is consumed extensively in South Africa. Due to the spontaneous nature of the sorghum fermentation considerable variations in the sensory and microbial quality of the end-product may occur, thus hampering large-scale production of this food. The use of starter cultures purified from the fermented sorghum may be an alternative approach to obtain ting of consistent quality. The aim of this study was therefore to identify the lactic acid bacteria (LAB) associated with ting fermentation using a polyphasic approach. Phenotypic characterization and sequence analysis of the genes encoding the 16S subunit of the ribosomal RNA (rrs) and phenylalanyl tRNA synthase (pheS) were used. The results of these analyses showed that ting fermentation involved at least three different species of LAB, i.e. Lactobacillus fermentum, L. plantarum and L. rhamnosus. To our knowledge, this is the first report of polyphasic taxonomic characterization of LAB from this food. This research forms an essential first step towards the development of relevant starter cultures to produce ting of consistent quality

Prozone in malaria rapid diagnostics tests: how many cases are missed?

<p>Abstract</p> <p>Background</p> <p>Prozone means false-negative or false-low results in antigen-antibody reactions, due to an excess of either antigen or antibody. The present study prospectively assessed its frequency for malaria rapid diagnostic tests (RDTs) and <it>Plasmodium falciparum </it>samples in an endemic field setting.</p> <p>Methods</p> <p>From January to April 2010, blood samples with <it>P. falciparum </it>high parasitaemia (≥ 4% red blood cells infected) were obtained from patients presenting at the Provincial Hospital of Tete (Mozambique). Samples were tested undiluted and 10-fold diluted in saline with a panel of RDTs and results were scored for line intensity (no line visible, faint, weak, medium and strong). Prozone was defined as a sample which showed no visible test line or a faint or weak test line when tested undiluted, and a visible test line of higher intensity when tested 10-fold diluted, as observed by two blinded observers and upon duplicate testing.</p> <p>Results</p> <p>A total of 873/7,543 (11.6%) samples showed <it>P. falciparum</it>, 92 (10.5%) had high parasitaemia and 76 were available for prozone testing. None of the two Pf-pLDH RDTs, but all six HRP-2 RDTs showed prozone, at frequencies between 6.7% and 38.2%. Negative and faint HRP-2 lines accounted for four (3.8%) and 15 (14.4%) of the 104 prozone results in two RDT brands. For the most affected brand, the proportions of prozone with no visible or faint HRP-2 lines were 10.9% (CI: 5.34-19.08), 1.2% (CI: 0.55-2.10) and 0.1% (CI: 0.06-0.24) among samples with high parasitaemia, all positive samples and all submitted samples respectively. Prozone occurred mainly, but not exclusively, among young children.</p> <p>Conclusion</p> <p>Prozone occurs at different frequency and intensity in HRP-2 RDTs and may decrease diagnostic accuracy in the most affected RDTs.</p

Integration and expression of alpha-amylase and endoglucanase genes in the Lactobacillus plantarum chromosome.

A commercial grass silage starter strain of Lactobacillus plantarum was transformed by high-frequency electroporation with plasmids containing an alpha-amylase gene from Bacillus stearothermophilus and an endoglucanase gene from Clostridium thermocellum. Both genes were expressed from their native regulatory signals, and active enzymes were found in the supernatant. However, the segregational stability of the transforming plasmids was rather low. Therefore, the transforming genes were inserted in the L. plantarum chromosome by means of single homologous recombination. In the majority of the transformants, this led to extremely stable segregation and expression of the transforming genes, without generating secondary mutations in the host. Increased selective pressure led to tandem amplification of the transforming DNA. The transformed strains demonstrated the ability of L. plantarum to express heterologous gene products; they can be used to detect the inoculum in silage ecology studies; and they demonstrate the feasibility of engineering truly cellulolytic silage starter bacteria

Use of microbial communities for human and animal health

The present invention relates to a mixture of bacteria belonging to at least 6 or 7 different and specific bacterial species preferably for use to prevent or treat gastro-intestinal disorders. Preferably, said mixture of bacteria are grown together in a fermenter prior to administering said mixture to a subject in order to prevent or treat said disorder