P. Semjonovs

University of Latvia, Riga, Riga, Latvia

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Publications (5)3.77 Total impact

  • Research Journal of Microbiology 03/2014; 9(3):129-141. DOI:10.3923/jm.2014.129.141
  • P. Semjonovs, I. Denina, R. Linde
    Journal of Medical Sciences(Faisalabad) 03/2014; 14(3):147-152. DOI:10.3923/jms.2014.147.152
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    ABSTRACT: Use of stevia-derived sweeteners was recently officially approved by the European Commission, and their application in the food industry has increased, especially in functional foods. However, there are scarce data about the influence of stevia on probiotic bacteria, which are important both as an inhabitant of the human gut and as a functional food additive. Taking into consideration the broad application of Lactobacillus reuteri in functional foods, the aim of the research was to evaluate the influence of stevia glycosides on its growth. Six Lact. reuteri strains were tested for their ability to grow in the presence of stevioside and rebaudioside A (0·2-2·6 g l(-1) ). The effect of stevia glycosides on biomass concentration, cell count, pH and lactic and acetic acid synthesis was analysed. Both glycosides impaired the growth of analysed strains. However, the inhibitory effect was strain specific, and the concentration-dependent effect was not observed for all parameters. The most pronounced concentration-dependent effect was on lactic and acetic acid production. Taking into account the observed strain-specific inhibitory effect of stevia glycosides, it could be suggested to evaluate the influence of them on each strain employed before their simultaneous application in functional foods. The study showed that the growth of Lactobacillus reuteri strains was inhibited in the presence of stevia sweeteners stevioside and rebaudioside A. Probiotics, for example Lact. reuteri strains, are often used as functional additives in health foods and are an important natural inhabitant of the human gastrointestinal tract. Stevia glycosides application in food is increasing; yet, there are no data about the influence of stevia glycosides on Lact. reuteri growth and very few data on growth of other lactobacilli, either in probiotic foods or in the gastrointestinal tract. This research shows that it is necessary to evaluate the influence of stevia glycosides on other groups of micro-organisms in further research.
    Letters in Applied Microbiology 10/2013; DOI:10.1111/lam.12187 · 1.75 Impact Factor
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    Pavels Semjonovs, Peteris Zikmanis
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    ABSTRACT: A novel strain of lactic acid bacteria Pediococcus pentosaceus P 773 was isolated from spoiled beer and identified by means of 16S rDNA sequence analysis. The ability to assimilate lactose as a sole carbon source as a specific feature for this strain was detected and confirmed on dairy substrates. In the presence of sucrose containing substrates (sucrose, raffinose) this P. pentosaceus P 773 lactose-positive strain produced a complex of extracellular polysaccharides (Qp=0.08g/l/h) with a molecular mass about 2,000kDa composed by glucose and fructose residues at a ratio 3:1, respectively. These exopolysaccharides were capable to stimulate the growth rate and biomass productivity of common constituent cultures of probiotic dairy starters (Bifidobacterium lactis, Lactobacillus acidophilus, Streptococcus thermophilus) as well as were assimilated as a sole carbon source by these strains. The present study confirmed the presence of lactose-positive and exopolysaccharide-producing strain of P. pentosaceus in natural environment which could be used as a starter culture to impart more functional attributes to fermented food.
    European Food Research and Technology 07/2008; 227(3):851-856. DOI:10.1007/s00217-007-0796-4 · 1.39 Impact Factor
  • P. Semjonovs, P. Zikmanis, M. Bekers
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    ABSTRACT: Supplementation of milk and oat hydrolysate containing medium with Jerusalem artichoke concentrate (JAC) and subsequent fermentation with probiotic dairy starters resulted in substantial stimulation of probiotics Bifidobacterium lactis and Lactobacillus acidophilus as well as yogurt starter culture Lactobacillus bulgaricus development and acidification rate. The strain-specific responses of the general yogurt cultures, as well as probiotics to the addition of JAC, should be considered to achieve optimal composition of probiotic strains and conformable fermentation conditions. JAC is suggested to be perspective prebiotic additive for fermented synbiotic milks or oat-hydrolysate-based products.
    Food Biotechnology 12/2007; 21(4):349-363. DOI:10.1080/08905430701707802 · 0.64 Impact Factor