In vivo colonization by different Lactobacillus strains on human intestinal mucosa of healthy volunteers was studied together with the effect of Lactobacillus administration on different groups of indigenous bacteria. A total of 19 test strains were administered in fermented oatmeal soup containing 5 x 10(6) CFU of each strain per ml by using a dose of 100 ml of soup per day for 10 days. Biopsies were taken from both the upper jejunum and the rectum 1 day before administration was started and 1 and 11 days after administration was terminated. The administration significantly increased the Lactobacillus counts on the jejunum mucosa, and high levels remained 11 days after administration was terminated. The levels of streptococci increased by 10- to 100-fold in two persons, and the levels of sulfite-reducing clostridia in the jejunum decreased by 10- to 100-fold in three of the volunteers 1 day after administration was terminated. In recta, the anaerobic bacterium counts and the gram-negative anaerobic bacterium counts decreased significantly by the end of administration. Furthermore, a decrease in the number of members of the Enterobacteriaceae by 1,000-fold was observed on the rectal mucosa of two persons. Randomly picked Lactobacillus isolates were identified phenotypically by API 50CH tests and genotypically by the plasmid profiles of strains and by restriction endonuclease analysis of chromosomal DNAs.(ABSTRACT TRUNCATED AT 250 WORDS)
The taxonomic position of 12 isolates tentatively assigned to the genus Bifidobacterium on the basis of a limited phenotypic characterization was examined. The isolates were collected between 1978 and 2005 in Belgium, Sweden and Norway, and originated from various human clinical samples, including urine, blood, urethra, oral cavity, tonsil, and abscesses of lung and aortic valve. On the basis of band number and clustering analysis, repetitive DNA element-based PCR fingerprinting using the BOXA1R and (GTG)(5) primers indicated that the clinical isolates represented a taxon probably not belonging to the genus Bifidobacterium. Analysis of 16S rRNA gene sequence similarities revealed that the isolates were most closely affiliated to Parascardovia denticolens LMG 18312(T) (93.0-93.2 %), Scardovia inopinata LMG 18313(T) (92.9-93.1 %) and other members of the Bifidobacteriaceae, indicating that the isolates belong to a novel genus within that family. This observation was further substantiated by the results of partial sequencing of the heat-shock protein 60 gene (hsp60) and determination of the DNA G+C contents (47.3-48.3 mol%). Members of the novel taxon can be phenotypically distinguished from S. inopinata, P. denticolens and Gardnerella vaginalis by the ability to grow on agar under aerobic conditions and on the basis of positive reactions for acid production from L-arabinose, raffinose, salicin and D-xylose. Unambiguous phenotypic differentiation from Aeriscardovia aeriphila and Bifidobacterium species may be difficult, so phenotypic analyses should be complemented by molecular methods. The values for DNA-DNA binding among four members of the novel genus were in the range of 89-100 %, indicating that the strains should be considered as a single novel species of a novel genus, for which the name Alloscardovia omnicolens gen. nov., sp. nov. is proposed. The type strain of Alloscardovia omnicolens is CCUG 31649(T) (=LMG 23792(T)).
The amperometric biosensor for ethanol determination based on alcohol oxidase immobilised by the method of electrochemical polymerization has been developed. The industrial screen-printed platinum electrodes were used as transducers for creation of amperometric alcohol biosensor. Optimal conditions for electrochemical deposition of an active membrane with alcohol oxidase has been determined. Biosensors are characterised by good reproducibility and operational stability with minimal detection limit of ethanol 8 x 10(-5) M. The good correlation of results for ethanol detection in wine and during wine fermentation by using the developed amperometric biosensor with the data obtained by the standard methods was shown (r = 0.995).
During the spring of 2006, a national disease outbreak caused by Shiga toxin-producing Escherichia coli (STEC) O103:H25 was investigated in Norway. At the time of the outbreak the Norwegian School of Veterinary Science was the national reference laboratory for E. coli O157 in food, and the microbiological investigations to identify the food source were performed there. Food- and environmental samples (n=931) were collected by the Norwegian Food Safety Authorities following two different hypotheses i) that minced meat was the source of STEC, and ii) that fermented sausage was the source of STEC. Twenty seven food samples, all collected following the latter hypothesis contained eae-positive E. coli O103:H25, but none of these were stx-positive. By PFGE it was shown that isolates from one particular type of fermented sausage "morr sausage 1" were identical to the isolates from patients. Samples of sheep meat that were linked epidemiologically to meat used for sausage production also contained isolates identical or closely related to patient strains. The presented study underpins epidemiological indications that fermented sausage was the source of the outbreak, but points specifically to one particular brand of sausage as the source.
A large outbreak of enterohaemorrhagic Escherichia coli (EHEC) infections occurred in southern Sweden during autumn 2002. A matched case-control study was performed and indicated an association between consumption of fermented sausage and EHEC infection (odds ratio 5.4, P
Fermented milk (FM) with putative antihypertensive effect in humans could be an easy applicable lifestyle intervention against hypertension. The mode of action is supposed to be through active milk peptides, shown to possess in vitro ACE-inhibitory effect. Blood pressure (BP) reductions upto 23?mm?Hg have been reported in spontaneously hypertensive rats fed FM. Results from human studies of the antihypertensive effect are inconsistent. However, many studies suffer from methodological weaknesses, as insufficient blinding and the use of office BP measurements. We conducted a randomised, double-blind placebo-controlled study of the antihypertensive effect of Lactobacillus helveticus FM in 94 prehypertensive and borderline hypertensive subjects. The participants were randomised into three treatment groups with a daily intake of 150?ml of FM, 300?ml of FM or placebo (chemically acidified milk). The primary outcome was repeated 24-h ambulatory BP measurements. There were no statistically significant differences in the outcome between the groups (systolic BP (SBP), P=0.9; diastolic BP (DBP), P=0.2). However, the group receiving 300?ml FM had reduced BP across the 8-week period in several readings, which could be compatible with a minor antihypertensive effect. Heart rate and lipids remained unchanged between groups. Hence, our study does not support earlier studies measuring office BP-measurements, reporting antihypertensive effect of FM. Based on straight performed 24-h ambulatory BP measurements, milk fermented with Lactobacillus helveticus does not posses significant antihypertensive effect.
Fermented foods and beverages are an integral part of the human diet globally. Understanding the microbial interactions within these fermenting ecosystems is required to deliver safe products with desirable consumer properties, and moreover, maintenance of these traditions. Effective tools are required for documentation of cultures in traditional and artisanal fermented products, for sensory quality and safety improvements, in some cases for starter culture design for commercialization and potentially for supporting sustainable food systems. Here we trace the developments of sequence-based molecular technologies for investigating the diversity and functionality of microbiota in traditional or indigenous fermented foods and beverages. The opportunities of phylobiomics, metagenomics and metatranscriptomics to enrich our knowledge of fermenting microbial ecosystems are presented.
Portuguese chouriço de vinho is made by drying coarsely minced meat and fat that has been previously marinated with wine (usually red), salt, and garlic for 1 to 2 days at a low temperature (4 to 8 °C). This procedure may improve the microbiological safety of the product. The aim of this study was to evaluate the behavior of three pathogens in this product, Salmonella spp., Listeria monocytogenes, and Staphylococcus aureus, to establish the minimum period of drying and maturation necessary to render safe products. The pathogens were inoculated in the chouriço de vinho batter. A factorial design was used to study the following variables in the fermentation process: (i) the presence or absence of an indigenous Lactobacillus sakei starter culture; (ii) the presence or absence of fermentable carbohydrates; and (iii) the salt level (1.5 or 3%). The samples were analyzed 24 h after the preparation of the batter (at stuffing); after 7, 15, and 30 days of drying; and after 30 days of storage at 4 °C under vacuum. Under all of the conditions studied, the levels of the three pathogens decreased during the drying period. In the early stages of drying, the addition of L. sakei starter culture and/or carbohydrates resulted in lower levels of gram-positive pathogens. After 15 days of drying, populations of all pathogens decreased by ca. 2 log in all samples. At that sampling time, L. monocytogenes was undetectable in the chouriço de vinho with L. sakei starter culture and carbohydrates. The mean count of S. aureus after 15 days of drying was below 1 log CFU/g. After 30 days of drying, no pathogens were detected. The drying period could be shortened to 15 days when considering only the gram-positive pathogens studied and the use of a starter culture and carbohydrates. Due to the low infective dose of Salmonella spp., the product should be considered safe after 30 days, when this pathogen became undetectable.
Biological activity was examined on Alaska pollack sikhae produced with 4 treatments (by irradiating at 5 or 10 kGy, or by adding either 0.1 or 0.3% of chitooligosaccharide), compared with control (2-step fermentation only) during fermentation at -2 degrees C. The extracts (500 ppm level) of sikhae had antimicrobial activities against 4 different strains of food poisoning bacteria such as Staphy. aureus, B. subtilis, B. cereus, and L. monocytogenes. Antioxidative activity (EDA(50), 11.55 mg/mL) in control group increased with time up to 60 days of fermentation but decreased thereafter, while those levels in other products were kept within 10.60-18.30 mg/mL ranges during fermentation. Inhibitory activity of angiotensin-I converting enzyme (ACE) (IC(50), 1.51-2.89 mg/mL) in all products was observed during fermentation except at 0 day. Inhibitory activity of xanthine oxidase (XO) (IC(50), 0.65-0.87 mg/mL) in all products also increased with time up to 30 days of fermentation. Without irradiating or adding of chitooligosaccharide, Alaska pollack sikhae showing biological activities was enough by 2-step fermentation and storage at -2 degrees C only.