Characterization of the gor gene of the lactic acid bacterium Streptococcus thermophilus CNRZ368

ABSTRACT We describe the dynamics of changes in the intracellular pH (pHi) values of a number of lactic acid bacteria in response to a rapid drop in the extracellular pH (pHex). Strains of Lactobacillus delbrueckii subsp.bulgaricus, Streptococcus thermophilus, andLactococcus lactis were investigated. Listeria innocua, a gram-positive, non-lactic acid bacterium, was included for comparison. The method which we used was based on fluorescence ratio imaging of single cells, and it was therefore possible to describe variations in pHi within a population. The bacteria were immobilized on a membrane filter, placed in a closed perfusion chamber, and analyzed during a rapid decrease in the pHex from 7.0 to 5.0. Under these conditions, the pHi of L. innocua remained neutral (between 7 and 8). In contrast, the pHi values of all of the strains of lactic acid bacteria investigated decreased to approximately 5.5 as the pHex was decreased. No pronounced differences were observed between cells of the same strain harvested from the exponential and stationary phases. Small differences between species were observed with regard to the initial pHi at pHex 7.0, while different kinetics of pHiregulation were observed in different species and also in different strains of S. thermophilus.

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Characterization of the lactic acid bacteria in artisanal dairy products

Journal of Dairy Research ◽

10.1017/s0022029997002185 ◽

1997 ◽

Vol 64 (3) ◽

pp. 409-421 ◽

Cited By ~ 204

Author(s):

TIMOTHY M. COGAN ◽

MANUELA BARBOSA ◽

ERIC BEUVIER ◽

BRUNA BIANCHI-SALVADORI ◽

PIER S. COCCONCELLI ◽

...

Keyword(s):

Lactic Acid ◽

Lactic Acid Bacteria ◽

Broad Spectrum ◽

Acid Production ◽

Dairy Products ◽

Streptococcus Thermophilus ◽

Listeria Innocua

In all, 4379 isolates from 35 products, including 24 artisanal cheeses, were surveyed with a view to identifying strains that could be used as starters in commercial dairy fermentations. Of the isolates, 38% were classified as Lactococcus, 17% as Enterococcus, 14% as Streptococcus thermophilus, 12% as mesophilic Lactobacillus, 10% as Leuconostoc and 9% as thermophilic Lactobacillus. Acid production by the isolates varied considerably. Of the 1582 isolates of Lactococcus and 482 isolates of mesophilic Lactobacillus tested, only 8 and 2% respectively produced sufficient acid to lower the pH of milk to <5·3 in 6 h at 30°C. In contrast, 53, 32 and 13% of Str. thermophilus, thermophilic Lactobacillus and Enterococcus isolates respectively reduced the pH to 5·3. These isolates were found only in some French, Italian and Greek cheeses. Bacteriocins were produced by 11% of the 2257 isolates tested and 26 of them produced broad-spectrum bacteriocins which inhibited at least eight of the ten target strains used, which included lactic acid bacteria, clostridia and Listeria innocua. The most proteolytic of the 2469 isolates tested were Str. thermophilus from Fontina cheese followed by Enterococcus from Fiore Sardo and Toma cheese and thermophilic Lactobacillus from all sources. Exopolysaccharides were produced by 5·3% of the 2224 isolates tested.

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Purification and characterization of an extracellular α-amylase produced by Lactobacillus manihotivorans LMG 18010T, an amylolytic lactic acid bacterium

Enzyme and Microbial Technology ◽

10.1016/s0141-0229(00)00230-1 ◽

2000 ◽

Vol 27 (6) ◽

pp. 406-413 ◽

Cited By ~ 74

Author(s):

G Aguilar ◽

J Morlon-Guyot ◽

B Trejo-Aguilar ◽

J.P Guyot

Keyword(s):

Lactic Acid ◽

Lactic Acid Bacterium ◽

Purification And Characterization

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Applications of CRISPR-Cas systems in lactic acid bacteria

FEMS Microbiology Reviews ◽

10.1093/femsre/fuaa016 ◽

2020 ◽

Vol 44 (5) ◽

pp. 523-537 ◽

Cited By ~ 1

Author(s):

Avery Roberts ◽

Rodolphe Barrangou

Keyword(s):

Lactic Acid ◽

Lactic Acid Bacteria ◽

Streptococcus Thermophilus ◽

Starter Cultures ◽

Natural Environments ◽

Gene Therapies ◽

The Past ◽

Food And Agriculture ◽

Functionally Diverse

ABSTRACT As a phenotypically and phylogenetically diverse group, lactic acid bacteria are found in a variety of natural environments and occupy important roles in medicine, biotechnology, food and agriculture. The widespread use of lactic acid bacteria across these industries fuels the need for new and functionally diverse strains that may be utilized as starter cultures or probiotics. Originally characterized in lactic acid bacteria, CRISPR-Cas systems and derived molecular machines can be used natively or exogenously to engineer new strains with enhanced functional attributes. Research on CRISPR-Cas biology and its applications has exploded over the past decade with studies spanning from the initial characterization of CRISPR-Cas immunity in Streptococcus thermophilus to the use of CRISPR-Cas for clinical gene therapies. Here, we discuss CRISPR-Cas classification, overview CRISPR biology and mechanism of action, and discuss current and future applications in lactic acid bacteria, opening new avenues for their industrial exploitation and manipulation of microbiomes.

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Characterization of Lactose Utilization and β-Galactosidase in Lactobacillus brevis KB290, the Hetero-Fermentative Lactic Acid Bacterium

Current Microbiology ◽

10.1007/s00284-012-0216-2 ◽

2012 ◽

Vol 65 (6) ◽

pp. 679-685 ◽

Cited By ~ 4

Author(s):

Hiroyuki Honda ◽

Nobuhiro Yajima ◽

Tadao Saito

Keyword(s):

Lactic Acid ◽

Lactic Acid Bacterium ◽

Lactobacillus Brevis ◽

Lactose Utilization

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Characterization of non-starter lactic acid bacteria in traditionally produced home-made Radan cheese during ripening

Archives of Biological Sciences ◽

10.2298/abs1101001j ◽

2011 ◽

Vol 63 (1) ◽

pp. 1-10 ◽

Cited By ~ 6

Author(s):

Natasa Jokovic ◽

Maja Vukasinovic ◽

Katarina Veljovic ◽

Maja Tolinacki ◽

L. Topisirovic

Keyword(s):

Lactic Acid ◽

Lactic Acid Bacteria ◽

Lactobacillus Plantarum ◽

Enterococcus Faecium ◽

Leuconostoc Mesenteroides ◽

Streptococcus Thermophilus ◽

Predominant Species ◽

Lactobacillus Paraplantarum ◽

Good Agreement

Two hundred thirteen non-starter lactic acid bacteria isolated from Radan cheese during ripening were identified with both a classical biochemical test and rep-PCR with (GTG)5 primer. For most isolates, which belong to the Lactococcus lactis subsp. lactis, Leuconostoc mesenteroides, Lactobacillus plantarum, Lactobacillus paraplantarum and Enterococcus faecium, a phenotypic identification was in good agreement with rep-PCR identification. Lactococeus lactis subsp. lactis, Enterococcus faecium and subspecies from the Lenconostoc mesenteroides group were the dominant population of lactic acid bacteria in cheese until 10 days of ripening and only one Streptococcus thermophilus strain was isolated from the 5-day-old cheese sample. As ripening progressed, Lactobacillus plantarum became the predominant species together with the group of heterofermentative species of lactobacilli that could not be precisely identified with rep-PCR.

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