Con la finalidad de obtener bacterias ácido lácticas productoras de bacteriocinas se recolectaron 33 muestras de quesos artesanales provenientes de Lima y provincias y se aislaron 341 cepas de lactobacilos según los procedimientos establecidos por el Manual de Bergey. Las especies de lactobacilos aisladas con mayor frecuencia fueron Lactobacillus casei 56 % (191) y Lactobacillus plantarum 35.8 % (122). Sólo el 16.42 % (56/341) de los aislados presentaron actividad bacteriocinogénica frente a Lactobacillus acidophilus ATCC 4356. Los sobrenadantes de los cultivos bacteriocinogénicos se ajustaron el pH a 6.5 para descartar la acción de ácidos orgánicos, además se determinó el péroxido de hidrógeno por acción de la catalasa. La constitución bioquímica de las bacteriocinas presentes en los sobrenadantes fue determinada enzimáticamente utilizando pronasa E, a -amilasa y lipasa. El 53 % (30) de las bacteriocinas fueron de naturaleza lipoproteica, 25 % (14) glicolipoproteica, 13 % (7) glicoproteica y 9 % (5) solamente proteica. Por otro lado, los sobrenadantes fueron sometidos a tratamientos térmicos de 60, 80 y 100 °C, a pH 4, 7 y 9, y a temperaturas de conservación de 4, 15 y 32 °C y se encontró que la termoestabilidad fue de 60 a 80 °C, el pH óptimo de 4 a 7 y la temperatura óptima de conservación de 4 a 32 °C. Las bacteriocinas presentes en los sobrenadantes de los diferentes aislados inhibieron el crecimiento de cepas de Bacillus cereus UA05, Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 10536, Salmonella typhimurium ATCC 14028, Salmonella choleraesuis ATCC 10708, Shigella sonnei ATCC 9290 y Pseudomonas aeruginosa ATCC 9027. Sin embargo, Listeria innocua UP01 fue resistente. El aislado identificado como Lactobacillus plantarum LM1 produjo la bacteriocina con los mejores parámetros fisicoquímicos experimentados y además presentó un amplio espectro de inhibición contra los microorganismos indicadores evaluados. Palabras Clave: bacterias ácido lácticas, bacteriocinas, lactobacilos, Lactobacillus plantarum, quesos artesanales / The aim of this study was to get bacteriocin – producing lactic acid bacteria. For the purpose of this study, thirty three samples of artisanal cheeses from Lima and provinieses were collected, and three hundred and forty one strains of lactobacilli were isolated according to the procedures established by Bergey’s Manual. The most frequently isolated species were Lactobacillus casei 56% (191) and Lactobacillus plantarum 35.8% (122). Only 16.42% (56/341) of the isolates showed bacteriocinogenic activity against Lactobacillus acidophilus ATCC 4356. The supernatants of bacteriocinogenic cultures were adjusted to pH 6.5 to rule out the action of organic acids, and it was determined the presence of hydrogen peroxide by the assay with catalase. The biochemical constitution of the bacteriocins present in the supernatants was determined using enzymatically pronase E, a - amylase and lipase. The 53% (30) of bacteriocins was of lipoproteinaceous nature, 25% (14) of glycolipoproteinaceous nature, 13% (7) of glycoproteinaceous nature, and 9% (5) only of proteinaceous nature. On the other hand, the supernatants were exposed to various heat treatments at 60, 80, and 100°C, to pH variation at 4, 7, and 9, and to storage temperatures at 4, 15 and 32°C, and it was found that the thermostability of bacteriocins was found from 60 to 80°C, the optimum pH was from 4 to 7, and the optimum storage temperature was from 4 to 32°C. The bacteriocins present in the supernatants of the different isolates inhibited the growth of Bacillus cereus UA05, Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 10536, Salmonella typhimurium ATCC 14028, Salmonella choleraesuis ATCC 10708, Shigella sonnei ATCC 9290 and Pseudomonas aeruginosa ATCC 9027. However, Listeria innocua UP01was resistant. The isolate identified as Lactobacillus plantarum LM1 produced the bacteriocin with the best physicochemical parameters, and showed a broad spectrum of inhibition against the indicator microorganisms. Key words: Lactic acid bacteria, bacteriocins, lactobacilli, Lactobacillus plantarum, artisanal cheeses.

Thèse (M.Sc.)--Université Laval, 2009. / Bibliogr.: f. [110]-120. Publié aussi en version électronique dans la Collection Mémoires et thèses électroniques.

Thesis (M.S.)--Ball State University, 2009. / Title from PDF t.p. (viewed on Dec. 14, 2009). Includes bibliographical references (p. 74-76).

1. Ištirtos registruotos Lactobacillus plantarum U-14, kuri išskirta iš sveikos karvės makšties ir Lactobacillus fermentum U-5, kuri išskirta iš sveiko veršelių fekalijų, padermės, nustatytos jų optimalios kultivavimo temperatūros, įvertintos jų probiotinės savybės, nustatytas antagonistinis aktyvumas, atsparumas antibiotikams bei įvertinta liofilizacijos įtaka šioms laktobacilų padermėms. 2. Liofilizacijos būdu pagamintas probiotikas, sudarytas iš Lactobacillus plantarum U-14 ir Lactobacillus fermentum U-5 padermių, nustatytas laktobacilų gyvybingumas preparate laikant vienus metus +4oC temperatūroje. 3. Nustatyta probiotiko profilaktinė dozė naujagimiams veršeliams girdant su krekenomis arba pienu pirmas 10 gyvenimo dienų, stebint veršelių klinikinius požymius, įvertinant paros priesvorį, įtaką bendram enterobakterijų ir laktobacilų kiekiui bei nustatant laktobacilų rūšinę sudėtį fekalijose įvertinant kraujo morfologinius ir biocheminius parametrus.4. Nustatyta probiotiko profilaktinė dozė veršeliams, kuri buvo – 4g/d. ir ji palyginta su probiotiko Yeasture profilaktine doze. / 1.The registered strains of Lactobacillus plantarum U-14 isolated from the vagina of healthy cow and Lactobacillus fermentum U-5 isolated from the faeces of healthy calve were studied, the optimal temperature for the cultivation was defined, were evaluated their probiotic properties, the antagonistic activity, resistance to antibiotics and the effect of lyophilization on these strains of lactobacillus were studied. 2.The probiotic preparation, consisting of Lactobacillus plantarum U-14 and Lactobacillus fermentum U-5 strains was produced by the method of lyophilization and the viability of lactobacillus during the period of 1 year storage at +4oC temperature was defined. 3.The preventive dose of probiotic preparation for neonate calves given with colostrum or milk was defined during the first 10 days, the clinical signs of calves, daily weight gain, effect on the total number of enterobacteria and lactobacillus were studied and the lactobacillus species composition in the faeces together evaluating morphological and biochemical indicators of blood was investigated. 4.The defined dose of probiotic preparation for calves was – 4g/d. and it was compared to the preventive dose of the preparation Yeasture.

No description available.

Plasmid curing experiments showed that the Caprylate-Esterase (CE) gene of Lactobacillus casei subsp. casei (LLG) is located on the LLG chromosome rather than on a plasmid. The enzyme was purified and shown to be a monomer with an apparent Mr of 32,000 on sodium dodecyl sulfate-polyacrylamide gels. The N-terminal end of the CE protein was microsequenced. A synthesized 29-mer oligonucleotide deduced from L. casei codon usage and the N-terminal peptide sequence was used as probe against an LLG genomic library. Library screening yielded one positive clone (pLLG1435) with an insert of 8 kb. Southern analysis of pLLG1435 showed that the oligonucleotide probe strongly hybridized with the 1.9 kb PstI/SphI fragment found within its insert. Th fragment was subcloned and its DNA sequence was determined and found to be closely related to the phosphoribosylformylglycinamidine synthase II gene of Bacillus subtilis. The gene was completely sequenced.

No description available.

Graduation date: 1993

No description available.

Freiburg i. Br., Univ., Diss., 2008.