Search results for "lactic acid"
showing 10 items of 660 documents
Microbial dynamics in durum wheat kernels during aging
2020
In the present work the microbial dynamics in wheat kernels were evaluated over time. The main aim of this research was to study the resistance of lactic acid bacteria (LAB) and yeasts associated to unprocessed cereals used for bread making during long term conservation. To this purpose four Triticum durum Desf. genotypes including two modern varieties (Claudio and Simeto) and two Sicilian wheat landraces (Russello and Timilia) were analysed by a combined culture-independent and -dependent microbiological approach after one, two or three years from cultivation and threshing. DNA based MiSeq Illumina technology was applied to reveal the entire bacterial composition of all semolina samples. T…
Fermentation profiles of Manzanilla-Aloreña cracked green table olives in different chloride salt mixtures.
2010
NaCl plays an important role in table olive processing affecting the flavour and microbiological stability of the final product. However, consumers demand foods low in sodium, which makes necessary to decrease levels of this mineral in fruits. In this work, the effects of diverse mixtures of NaCl, CaCl2 and KCl on the fermentation profiles of cracked directly brined Manzanilla-Aloreña olives, were studied by means of response surface methodology based in a simplex lattice mixture design with constrains. All salt combinations led to lactic acid processes. The growth of Enterobacteriaceae populations was always limited and partially inhibited by the presence of CaCl2. Only time to reach half …
Absence of malolactic activity is a characteristic of H+-ATPase-deficient mutants of the lactic acid bacterium Oenococcus oeni.
2003
ABSTRACT The lack of malolactic activity in H + -ATPase-deficient mutants of Oenococcus oeni selected previously was analyzed at the molecular level. Western blot experiments revealed a spot at 60 kDa corresponding to the malolactic enzyme only in the parental strain. Moreover, the mleA transcript encoding the malolactic enzyme was not detected by reverse transcription (RT)-PCR analysis of mutants. These results suggest that the malolactic operon was not transcribed in ATPase-deficient mutants. The mleR gene encoding a LysR-type regulatory protein which should be involved in expression of the malolactic genes was described previously for O. oeni . Results obtained in this study show that th…
Functional genomics of Lactobacillus casei establishment in the gut
2014
International audience; Although the composition of the gut microbiota and its symbiotic contribution to key host physiological functions are well established, little is known as yet about the bacterial factors that account for this symbiosis. We selected Lactobacillus casei as a model microorganism to proceed to genomewide identification of the functions required for a symbiont to establish colonization in the gut. As a result of our recent development of a transposon-mutagenesis tool that overcomes the barrier that had prevented L. casei random mutagenesis, we developed a signature-tagged mutagenesis approach combining whole-genome reverse genetics using a set of tagged transposons and in…
A metabolomic study of yeast/bacteria interactions
2015
As a complex microbial ecosystem, wine is a particularly interesting model for studying interactions between microorganisms. Contact-independent interactions (indirect interactions) between the yeast Saccharomyces cerevisae and the lactic acid bacterium Oenococcus oeni have a direct effect on malolactic fermentation (MLF), induction and completion, which is an important factor in wine quality. Yeast strains could be classified as MLF+ phenotype if it usually stimulates the bacterial growth or MLF- in the opposite case. The known metabolites that stimulate or inhibit the MLF cannot always explain the phenotypic distinction. In this work, a multidisciplinary workflow combining non-targeted me…
Tropical traditional fermented food, a field full of promise. Examples from the Tropical Bioresources and Biotechnology programme and other related F…
2013
International audience; In tropical countries, traditional fermented foods are usually home‐made products obtained through spontaneous fermentation or backslopping. They are now facing an evolution aiming at responding to quality, safety and mass production issues. This requires acquisition of knowledge on raw materials, microbial ecosystems and fermentation processes. Vietnam is a laboratory for such studies as traditional fermented foods play an important role in the diet of Vietnamese and as these foods are very diverse. Among the most popular are nem chua (sausage reminding Thai Nham), dua muoi (cabbage reminding Kimchi), tom chua (shrimps) and the well‐known nuoc mam. The challenge for…
Evaluation of the variations in chemical and microbiological properties of the sourdoughs produced with selected lactic acid bacteria strains during …
2022
This research aimed to analyze variations in chemical properties, microbiological characteristics and generated volatile organic compounds (VOCs) profile during sourdough fermentation. Sourdoughs were collected from different cities in Turkey at two different times and lactic acid bacteria (LAB) in the samples were identified with culture-independent and culture-dependent molecular methods. According to culture-dependent methodology, thirteen LAB species were identified. Lactobacillus spp. were identified as the major group according to MiSeq Illumina analysis. Technological potential of commonly isolated LAB species was evaluated. Due to high frequency of isolation, Fructilactobacillus san…
Vacuum impregnation as a tool to introduce biopreservatives in gilthead sea bream fillets (Sparus aurata)
2015
Abstract The aim of this study was to determine the possible technological uses of biopreservation and vacuum impregnation techniques to extend shelf life of gilthead sea bream fillets. Two impregnation media were studied: a solution containing lactic acid bacteria (LAB) and a nisin solution. Vacuum impregnation was carried out at 4 °C. Fillets were immersed in a vessel containing the impregnation solution and vacuum was applied during 5 min. After this time atmospheric pressure was restored leaving samples under the liquid for 5 min more. Weight gain, physico-chemical properties (moisture, pH, water activity and TVBN), color and microbiological counts were studied during 15 days of storage…
Pyrosequencing vs. culture-dependent approaches to analyze lactic acid bacteria associated to chicha, a traditional maize-based fermented beverage fr…
2015
The diversity of lactic acid bacteria (LAB) associated with chicha, a traditional maize-based fermented alcoholicbeverage from Northwestern Argentina, was analyzed using culture-dependent and culture-independent approaches.Samples corresponding to 10 production steps were obtained from two local producers at Maimará(chicha M) and Tumbaya (chicha T). Whereas by culture-dependent approach a few number of species(Lactobacillus plantarum and Weissella viridescens in chicha M, and Enterococcus faecium and Leuconostocmesenteroides in chicha T) were identified, a higher quantitative distribution of taxa was found in both beveragesby pyrosequencing. The relative abundance of OTUs was higher in chic…
Persistence of a mixed lactic acid bacterial starter culture during lysine fortification of sourdough breads by addition of pistachio powder
2020
Abstract Pistachio powder was added to flour or semolina to evaluate its contribution to increase the amount of lysine in bread. Bread production was carried out by sourdough technology using a selected 3-species (Lactobacillus sanfranciscensis/Leuconostoc citreum/Weissella cibaria) lactic acid bacterial (LAB) starter culture. All sourdoughs were subjected to a long-time fermentation (21 h) and showed levels of LAB around 109 CFU/g, indicating the suitability of pistachio powder for lactic fermentation. Yeasts were also detected, in particular in semolina trials. MiSeq Illumina technology was applied to investigate the bacterial composition of sourdoughs evidencing a different distribution …