Browsing by Author "Ryma Merabti"

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    First Insight into the Technological Features of Lactic Acid Bacteria Isolated from Algerian Fermented Wheat Lemzeiet
    (Springer, 2019-07-03) Ryma Merabti
    Abstract Fermented cereals are part of the main traditional diets of many people in Africa, usually obtained from artisanal production. The intensification of their manufacturing, responding to the consumers demand, requires a better control to ensure their sanitary, nutritional, and taste qualities, hence, the need of selecting accurate and safe starter cultures. In the present study, 48 lactic acid bacteria (LAB) strains, previously isolated from Algerian fermented wheat lemzeiet, were analyzed for different technological properties. 14 LAB strains, belonging to Pediococcus pentosaceus, Enterococcus faecium, Lactobacillus curvatus, Lactobacillus brevis, and Leuconostoc mesenteroides species, decreased rapidly the pH of the flour extract broth close to 4 or below. 91% of strains showed extracellular protease activity, but only 12% were amylolytics. 18 LAB strains inhibited or postponed the growth of three fungal targets Rhodotorula mucilaginosa UBOCC-A-216004, Penicillium verrucosum UBOCC-A-109221, and Aspergillus flavus UBOCC-A-106028. The strains belonging to Lactobacillus spp., Leuconostoc fallax, L. mesenteroides, and Weissella paramesenteroides were the most antifungal ones. Multiplex PCR for biogenic amines’ production did not reveal any of the genes involved in the production of putrescine, histamine, and tyramine for 17 of the 48 strains. The obtained results provided several candidates for use as starter culture in the future production of lemzeiet.
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    large diversity of lactic acid bacteria species is involved in the fermentation of wheat used for the manufacture of lemzeiet
    (Springer, 2015-02-13) Ryma Merabti
    Abstract Algerian couscous named lemzeiet is manufactured from fermented wheat. Historically performed in underground silos called matmor, the fermentation of wheat is now generally carried out in plastic jerrycans with or without addition of vinegar at the beginning of the fermentation. Culture-dependent and culture-independent methods (PCR-TTGE) were used to characterize lactic acid bacteria and to determine their dynamic and diversity over a two-year period, with and without the addition of vinegar. Fungi, physicochemical characteristics, and volatile compound profiles were also monitored. The isolates obtained from different stages of fermentation and from both processes were characterized by coupling different molecular methods (16SrRNA/pheS/rpoA gene sequencing, speciesspecific PCR, RAPD and PFGE). PCR-TTGE revealed
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    PHYSICOCHEMICAL PROPRIETIES OF LIPASE FROM NEWLY STREPTOMYCES SP. OLIVE POMACE ISOLATE
    (J Microbiol Biotech, 2024-02-01) Ryma Merabti
    Screening of new producing strains is required to meet the constant industrial demand for useful enzymes. In this context, an actinobacteria was isolated from the olive pomace, tested for extracellular lipase production, and identified by partial 16S rDNA sequencing. Then, the physicochemical characteristics of the enzyme are determined. Strain is a member of Streptomyces genus. Lipase was partially purified at 62.5 times, with a yield of 14.83% and a specific activity of 337.5 U/mg. Optimum activity was achieved at pH 7.0 and 60°C; it was completely preserved at pH 6.0 to 9.0, and more than 70% at 40 to 70°C, after 1 hour. The metal ions: K+, Na+, Ca2+, Co2+, Cu2+, Fe2+, Mg2+, Mn2+, and Zn2+ had no significant impact. Lipase activity was stable with ethylene diamine tetra acetic acid (EDTA), sodium dodecyl sulfate (SDS), H2O2, Triton x100, and Tween 80. Moreover, it was enhanced in butanol, chloroform, ethyl acetate, isopropanol, isobutyl acetate, hexane, petrol ether, and toluene. This enzyme can be suitable for various industrial applications.