The purpose of this review article on the lactic acid bacteria grew from an early curiosity and a desire to convey and impart the broad scope of literary information on their functions as starter cultures, in the manufacture of fermentation products such as dairy products and alcoholic beverages, as well as their contribution to better health. This review article is an attempt to empower the reader and to circumvent the difficult task in acquiring and elucidating a large body of information. The intent is to familiarize the reader with the various lactic species, their habitat or source, associated food, physiological characteristics, colonial morphology, biochemical characteristics, culture media (enrichment, nonselective, and selective), classic description, and taxonomy. This review provides information on Lactobacillus, Lactococcus, Leuconostoc, Pediococcus, Carnobacterium, and Enterococcus. Trends are presented, such as the use of nisin to extend food shelf-life and the current research premise that Probiotic strains may alter the intestinal flora and thus prevent intestinal wall penetration by pathogens.

The Lactic Acid Bacteria: A Literature Survey

In an investigation of the changes in the microflora along the pathway: kefir grains (A)→kefir made from kefir grains (B)→kefir made from kefir as inoculum (C), the following species of lactic acid bacteria (83–90%) of the microbial count in the grains) were identified: Lactococcus lactis subsp lactis, Streptococcus thermophilus, Lactobacillus delbrueckii subsp bulgaricus, Lactobacillus helveticus, Lactobacillus casei subsp pseudoplantarum and Lactobacillus brevis Yeasts (10–17%) identified were Kluyveromyces marxianus var lactis, Saccharomyces cerevisiae, Candida inconspicua and Candida maris In the microbial population of kefir grains and kefir made from them the homofermentative lactic streptococci (52–65% and 79–86%, respectively) predominated Within the group of lactobacilli, the homofermentative thermophilic species L delbrueckii subsp bulgaricus and L helveticus (70–87% of the isolated bacilli) predominated Along the pathway A→B→C, the streptococcal proportion in the total kefir microflora increased by 26–30% whereas the lactobacilli decreased by 13–23% K marxianus var lactis was permanently present in kefir grains and kefirs, whereas the dominant lactose-negative yeast in the total yeast flora of the kefir grains dramatically decreased in kefir C Journal of Industrial Microbiology & Biotechnology (2002) 28, 1–6 DOI: 101038/sj/jim/7000186

Lactic acid bacteria and yeasts in kefir grains and kefir made from them.

http://www.envismadrasuniv.org/General%20Ecology/pdf/Characterisation%20of%20naturally%20fermented%20sausages.pdf

Characterisation of naturally fermented sausages produced in the North East of Italy

A screening method for methicillin-resistant Staphylococcus aureus (MRSA) by using selective broth and real-time PCR (broth-PCR) was developed and evaluated. The samples (n = 304) were cultured in the broth overnight, followed by nuc gene detection by real-time PCR. nuc-negative samples were further checked for the presence of nuc amplification inhibitors by a PCR internal inhibitor assay. nuc-positive samples and nuc-negative samples with PCR inhibitors were cultured onto plates and processed further. The diagnostic values for this MRSA screening method were 93.3% sensitivity, 89.6% specificity, 31.8% positive predictive value, and 99.6% negative predictive value. The application of the broth-PCR method will be able to report most of the negative samples (258 of 289 [89.3%]) on the next morning and can save as much as 84.9% (258 of 304) of the labor and cost spent on processing the nuc-negative specimens on plates. In the study, all the samples were processed in parallel by the broth enrichment method and the plating method for comparison. To identify MRSA, the isolated oxacillin-resistant S. aureus strains were tested by a duplex real-time PCR targeting the mecA gene and the nuc gene. A collection of MRSA, methicillin-susceptible Staphylococcus aureus, methicillin-resistant Staphylococcus epidermidis, and methicillin-susceptible Staphylococcus epidermidis strains and a panel of standard strains of 11 bacterial species other than S. aureus were also tested by this method, which was proved to be a valuable tool for MRSA identification in a routine microbiological laboratory.

Rapid screening and identification of methicillin-resistant Staphylococcus aureus from clinical samples by selective-broth and real-time PCR assay.

H.J. JORGENSEN, T. MORK, H.R. HOGA˚ SEN AND L.M. RORVIK. 2005. Aims: To investigate the presence of enterotoxigenic Staphylococcus aureus in bulk milk and in a selection of rawmilk products.Methods and results: Samples of bovine (n ¼ 220) and caprine (n ¼ 213) bulk milk, and raw milk products(n ¼ 82) were analysed for S. aureus. Isolates were tested for staphylococcal enterotoxin (SE) production (SEA-SED) by reversed passive latex agglutination and for SE genes (sea–see, seg–sej) by multiplex PCR. Staphylococcusaureus was detected in 165 (75%) bovine and 205 (96AE2%) caprine bulk milk samples and in 31 (37AE8%) rawmilk product samples. Enterotoxin production was observed in 22AE1% and 57AE3% of S. aureus isolates frombovine and caprine bulk milk, respectively, while SE genes were detected in 52AE5% of the bovine and55AE8% of the caprine bulk milk isolates. SEC and sec were most commonly detected. A greater diversity of SEgenes were observed in bovine vs caprine isolates.Conclusions: Staphylococcus aureus seems highly prevalent in Norwegian bulk milk and isolates frequently produceSEs and contain SE genes. Enterotoxigenic S. aureus were also found in raw milk products.Signiﬁcance and Impact of the Study: Staphylococcus aureus in Norwegian bovine and caprine bulk milk mayconstitute a risk with respect to staphylococcal food poisoning from raw milk products.Keywords: bovine bulk milk, caprine bulk milk, enterotoxins, raw milk products, Staphylococcus aureus.

Peter Byrd Smith

Papers

The gram positive cocci