La conservación de alimentos por fermentación natural es ampliamente practicada por diversas comunidades nativas. El “masato” es producto de este proceso y constituye parte importante de la alimentación de los pobladores de la amazonía peruana. La masa de yuca, mandioca o cassava (Manihot esculenta, Crantz) utilizada en la preparación de esta bebida tradicional, constituye el substrato principal para el establecimiento de una microflora mixta ambiental, incluyendo las bacterias lácticas como responsables de la fermentación maloláctica, láctica y otras propiedades de interés industrial. La búsqueda de nuevas cepas nativas de bacterias lácticas productoras de sustancias antimicrobianas, adaptadas a las condiciones ambientales y materias primas regionales, es sumamente importante, para mejorar la calidad sensorial y sanitaria del “masato”. Para detectar cepas lácticas con propiedades antimicrobianas, se procesaron 11 muestras de “masato” procedentes de Pucallpa – Ucayali, las cuales fueron sembradas en agar Man Rogosa Sharpe (MRS) pH 6.5 e incubadas a 30° C por 72 horas en condiciones de microaerofilia. La caracterización morfológica, cultural, bioquímica y la actividad antimicrobiana se realizaron según Kandler Weiss (1986) y Tagg McGiven, (1971) respectivamente. De un total de 81 cepas de Lactobacillus aisladas, se identificaron 33 (41%) de Lactobacillus plantarum, 13 (16%) de Lactobacillus alimentarius, 12 (15%) de Lactobacillus acidophilus, 9 (11%) de Lactobacillus casei y en menores porcentajes Lactobacillus brevis, Lactobacillus delbrueckii, Lactobacillus fermentum, Lactobacillus amylophilus y Lactobacillus coryniformis. Se encontró además, 64 (78.9%) de Lactobacillus heterofermentativos y 17 (21.1%) de Lactobacillus homofermentativos. En todas las muestras de “masato” evaluadas, predominó Lactobacillus plantarum, seguido de Lactobacillus acidophilus y Lactobacillus alimentarius. De 8 cepas lácticas productoras evaluadas, Lactobacillus plantarum M4 fue la única cepa productora de una sustancia antimicrobiana que no es ácido orgánico ni agua oxigenada. Se demostró además, que la sustancia antimicrobiana neutralizada a pH 6,5 posee un reducido espectro antimicrobiano y es estable en un amplio rango de temperatura y pH. Asimismo, las cepas de Lactobacillus muestran un alto nivel de tolerancia a concentraciones de etanol agregadas al medio de cultivo, siendo mas del 80% de cepas aisladas tolerantes a 10% de etanol, mientras que 6% tolera concentraciones de hasta 12% v/v de etanol. Se proponen las cepas Lactobacillus plantarum 4M0.2, Lactobacillus plantarum M9.5, Lactobacillus acidophilus M2.9, Lactobacillus alimentarius 5M1.2 como una selección de cepas de interés biotecnológico, así como a Lactobacillus plantarum M4, cepa del estudio con mayor espectro antimicrobiano tolerante hasta una concentración de 8% v/v de etanol en el medio de cultivo. / The food preservation by natural fermentation is practiced by diverse native communities. The "masato" is product of this process and constitutes important part of the feeding of the population of peruvian amazonia. The mass of yucca, mandioca or cassava (Manihot esculenta, Crantz) used in the preparation of this traditional drink, constitutes the main substrate for the establishment of an environmental mixed microflora, including the lactic acid bacteria which are responsible for the malolactic and lactic fermentation and other properties of industrial interest. The search of new native strains of antimicrobial substances producing lactic bacteria, adapted to the environmental conditions and regional raw materials, is extremely important, to improve the sensorial and sanitary quality of the "masato". In order to detect lactic strains with antimicrobial properties, 11 samples of "masato" coming from Pucallpa - Ucayali were processed, which were seeded in agar Man Rogosa Sharpe (MRS) pH 6,5 and incubated to 30° C by 72 hours in microaerophilic conditions. The morphologic, cultural, biochemical characterization and the antimicrobial activity were made according to Kandler Weiss (1986) and Tagg McGiven, (1971) respectively. Of a total of 81 isolated strains of Lactobacillus, 33 (41%) of Lactobacillus were identified like Lactobacillus plantarum, 13 (16%) like Lactobacillus alimentarius, 12 (15%) like Lactobacillus acidophilus, 9 (11%) like Lactobacillus casei and in smaller percentage like Lactobacillus brevis, Lactobacillus delbrueckii, Lactobacillus fermentum, Lactobacillus amylophilus and Lactobacillus coryniformis. In addition, 64 (78.9%) and 17 (21.1%) of Lactobacillus were detected homofermenters and heterofermenters respectively. In all the evaluated samples of "masato", predominated Lactobacillus plantarum, followed of Lactobacillus acidophilus and Lactobacillus alimentarius. Of 8 evaluated antimicrobial substance producing lactic acid bacteria strains, Lactobacillus plantarum M4 was the only producing strain of a antimicrobial substance that is not acid organic nor oxygenated water. In addition, it was shown that the neutralized antimicrobial substance to pH 6.5 has a reduced antimicrobial spectrum and is stable in a wide range of temperature and pH. Also, the strains of Lactobacillus showed a high level of tolerance to concentrations of ethanol added to culture means, being but of 80% of tolerant isolated strains to 10% of ethanol, whereas 6% tolerated concentrations of up to 12% v/v of ethanol. We propose to Lactobacillus plantarum 4M0.2, Lactobacillus plantarum M9.5, Lactobacillus acidophilus M2.9, Lactobacillus alimentarius 5M1.2 like a selection of strains of biotechnological interest, as well as to Lactobacillus plantarum M4, strain of the study with greater antimicrobial spectrum and tolerance until 8% v/v concentration of ethanol added in culture mean.

In this study, alpha-Galactosidase (alpha-D-galactoside-galactohydrolase, EC 3.2.1.22) has been isolated, purified, and characterized from intracellular fraction of Lactobacillus helveticus ATCC 10797. It was purified by a combination of ammonium sulfate precipitation and fast performance liquid chromatography system using ion exchange and gel-filtration columns. This enzyme was purified to only 9.44 fold over the crude extract with a recovery of 1.8%. The km of 3.83 mM and Vmax of 416.44 mumol/min/mg protein were calculated from PNPG. The molecular mass was estimated to be 188 kDa by gel-filtration, but 90 kDa by SDS-PAGE, indicating two similar molecular weight subunits. The optimum temperature for enzyme activity was 37°C, but with a stability below 30°C. The optimum pH was at 6 with a stability of pH 4-8 range. / This enzyme was activated by 10 mM monovalent ions such as K+ , NH4+, Li+ and CS +, while the activity was inhibited by divalent ions such as Cu +2, Zn+2, F+2. About 40% of the enzyme activity was inhibited with 100 mM EDTA. alpha-Galactosidase was inhibited by 1mM glucose and galactose, 10 mM sucrose, high concentrations of melibiose, or raffinose and stachyose, but the least inhibitory effect was shown with fructose. / When the sugars were incubated with alpha-galactosidase, melibiose was hydrolyzed to glucose and galactose, raffinose to galactose and sucrose, while stachyose to galactose and sucrose with raffinose as intermediate product.

A programme of study was undertaken to asses the antimicrobial and potential immunological properties of fermented liquid feed fed to sows in late gestation period. A liquid feed fermented with Lactobacillus plantarum fed to the pregnant sow in late gestation had the potential to beneficially modify the microflora the lactating sows introduces into the environment, which was consequently reflected in beneficial changes in the gut microflora of their litters. In addition, colostrum from sows fed FLF had a significantly greater mitogenic activity on both intestinal ce11s (79326 ± 3069 CPM) and blood lymphocytes (1903 ± 204 CPM) compared with colostrum from dry feed fed sows (53433 ± 1568 CPM and 1231 ± 61.4 CPM respectively). The combined effects of higher milk quality and the reduction in the level of environmental contamination with faecal pathogens, achieved by FLF, may be important in achieving improved health status for both sows and piglets. A series of in vitro experiments were conducted in order to select a suitable new starter culture from LAB of porcine origin, which would have similar fermentative abilities to Lactobacillus plantarum, but could exert possible 'probiotic' effects on the host (pregnant sow). From a total of 87 faecal Lactobacillus strains, a homofermentative aggregating Lactobacillus salivarius, was selected for further in vivo studies as it was able to resist bile and acid conditions, had good adherence abilities to a11 intestinal compartments (mucus, epithelial cells, collagen), as well as being a potent stimulator of interleukin (IL)-12. In addition, it had comparable fermentation properties to the Lactobacillus plantarum that has been widely used to ferment FLF in this laboratory. In vivo experiments with porcine Lactobacillus salivarius strongly indicated that this bacterial strain is an effective inoculant for FLF, with a potential double role: the role of the starter culture and the role of probiotic. This could help sows to overcome disorders due to the stress associated with farrowing, enhance immunity of newborn piglets through better immunological quality of colostrum and control pathogen challenge for both sows and their newborn piglets.

Proefschrift Universiteit van Amsterdam. / Omslagtitel: Lactobacillus surface layer proteins. Met bibliogr., lit. opg. - Met samenvatting in het Nederlands.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1949. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves [70-72]).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1931. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves [88]-94).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1962. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 152-156).

Thesis (M.S.)--University of Wisconsin--Madison, 1970. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xi, 102 p.; also includes graphics (some col.). Includes bibliographical references (p. 95-102). Available online via OhioLINK's ETD Center

Thesis (D. Med. Scs.)--University of Tartu, 2006. / Vita. Includes bibliographical references.