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Browsing by Subject "lactic acid bacteria"

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  • DGGE analysis of probiotic-induced alteration in the canine faecal lactic acid bacteria microbiota 
    Peiponen, Susanna (University of HelsinkiHelsingin yliopistoHelsingfors universitet, 2008)
    Several canine clinical gastrointestinal problems, such as inflammatory bowel disease and small-intestinal bacterial overgrowth, are believed to be associated with bacteria. These conditions often lead to chronic diarrhea. Many canine gastrointestinal problems are treated with antibiotics, but due to increasing problems with antimicrobial resistance alternative therapies should be considered. One of these therapies is suggested be probiotic bacteria treatment, especially with members of the genus Lactobacillus due to their health-conferring properties. The probiotic characteristics of bacteria are linked to host specificity which is an important criterion for selection of a probiotic. Most of the commercial probiotic strains meant for dogs are not from canine origin. In addition many substances available in the Finnish market contain Enterococcus faecium, whose safety has been questioned due to it's pathogenic characteristics. This study was based on the study project investigating the effect of host-specific canine LAB on long term gastro-intestinal symptoms. The study was a randomized, double-blinded and placebo controlled trial. This study examined the changes in the canine faecal LAB microbiota caused by fed canine host-specific probiotic LAB. The purpose was to become familiar to the isolation of gastro-intestinal microbiota and to assess the potential alterations in the faeces by applicable methods. The most important methods were polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE). During the study DGGE analysis proved to be a working method for analyzing bacterial communities. When the method becomes more familiar, it will probably be as common in use as agarose gel electrophoresis due to it's advantages. Some alterations of the microbiota could be seen on the DGGE analysis. During the experiment the bands resembling those of standard strains were dominant. This implies the Lactobacillus strains of interest being able to survive the canine intestine. However, after feeding seized the bands formed by the strains of interest disappeared and were replaced with bands of indigenous LAB. Also after the feeding seized, some new bands appeared on DGGE gel. This implies a contribution of fed probiotic mixture to the enhanced prevalence of potential novel microbes.
  • Teollisuuden valmistaman suojakaasupakatun jauhelihan pilaajamaitohappobakteerit 
    Lehto, Jenni (University of HelsinkiHelsingin yliopistoHelsingfors universitet, 2009)
    The quality of easily spoiling minced meat is regularly inspected by food control authorities. The quality of minced meat near the sell-by date has often been found to be poorer than could be wished for. In previous studies psychrotrophic lactic acid bacteria have been found to be significant spoilage bacteria in modified atmosphere packed meat but the spoilage bacteria of minced meat have not been studied. An industrial manufacturer delivered 20 packages of modified atmosphere packed minced meat which were studied on the sell-by day (±1 day). The concentrations of lactic acid bacteria and enterobacteria in the minced meat samples were quantified on MRS agar and VRBG agar respectively. The appearance and smell of raw minced meat was judged organoleptically. 349 lactic acid bacteria isolates were identified using ribotyping based on numerical analysis. The DNA of the lactic acid bacteria was isolated and digested with the restriction enzyme HindIII. The DNA fragments were separated by agarose gel electrophoresis and transferred to a nylon membrane where the fragments were hybridized with a labelled probe. Thus the ribopatterns of the isolates could be visualised on the membrane. The ribopatterns were compared with corresponding patterns in the research group's database which comprises the ribopatterns of over 7000 strains. Identification of the isolates is based on the locations of type strains in the clusters created in the numerical analysis according to similarity of ribotypes. The lactic acid bacteria counts in the minced meat samples were 1,1 × 107 – 4,9 × 108 cfu/g (on average 1,9 × 108 cfu/g). Enterobacterial counts were 9,0 × 102 – 9,0 × 104 cfu/g (on average 1,4 × 104 cfu/g). Observations in the sensory evaluation included grayness and off-odours of varying strength. The off-odours were described as rancid and buttery. The most common species of lactic acic bacteria were identified to be Leuconostoc gasicomitatum (58 % of lactic acid bacteria isolates) and Leuconostoc gelidum (20 %). Other species were Carnobacterium divergens (10 %), Carnobacterium maltaromaticum (4 %), Lactococcus spp. (3 %), Leuconostoc mesenteroides (2 %), Lactobacillus algidus (1 %), Lactobacillus sakei (1 %), and Leuconostoc carnosum (1 %). In addition to these, 15 isolates were identified as Brochothrix thermospacta which appeared to grow on MRS along with lactic acid bacteria. Lactic acid bacteria, especially L. gasicomitatum and L. gelidum, were recognised as the spoilage bacteria of industrially manufactured, modified atmosphere packed minced meat. These organisms have been shown to grow on modified atmosphere packed meat during cold storage and to be connected with the formation of sour and buttery off-odours. L. gasicomitatum and L. gelidum are not part of the natural microbiota of slaughter animals and therefore the significance of the production environment as their source should be examined.

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