scholarly journals Enhancing the Sweetness of Yoghurt through Metabolic Remodeling of Carbohydrate Metabolism in Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus

2016 ◽  
Vol 82 (12) ◽  
pp. 3683-3692 ◽  
Author(s):  
Kim I. Sørensen ◽  
Mirjana Curic-Bawden ◽  
Mette P. Junge ◽  
Thomas Janzen ◽  
Eric Johansen
Keyword(s):  
Lactic Acid ◽  
Recombinant Dna ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Delbrueckii ◽  
Phosphotransferase System ◽  
Recombinant Dna Technology ◽  
Kinase Gene ◽  
Content Type ◽  
Metabolic Remodeling ◽  
Genes Encoding

ABSTRACTStreptococcus thermophilusandLactobacillus delbrueckiisubsp.bulgaricusare used in the fermentation of milk to produce yoghurt. These species normally metabolize only the glucose moiety of lactose, secreting galactose and producing lactic acid as the main metabolic end product. We used multiple serial selection steps to isolate spontaneous mutants of industrial strains ofS. thermophilusandL. delbrueckiisubsp.bulgaricusthat secreted glucose rather than galactose when utilizing lactose as a carbon source. Sequencing revealed that theS. thermophilusstrains had mutations in thegalKTEMpromoter, the glucokinase gene, and genes encoding elements of the glucose/mannose phosphotransferase system (PTS). These strains metabolize galactose but are unable to phosphorylate glucose internally or via the PTS. TheL. delbrueckiisubsp.bulgaricusmutants had mutations in genes of the glucose/mannose PTS and in the pyruvate kinase gene. These strains cannot grow on exogenous glucose but are proficient at metabolizing internal glucose released from lactose by β-galactosidase. The resulting strains can be combined to ferment milk, producing yoghurt with no detectable lactose, moderate levels of galactose, and high levels of glucose. Since glucose tastes considerably sweeter than either lactose or galactose, the sweetness of the yoghurt is perceptibly enhanced. These strains were produced without the use of recombinant DNA technology and can be used for the industrial production of yoghurt with enhanced intrinsic sweetness and low residual levels of lactose.IMPORTANCEBased on a good understanding of the physiology of the lactic acid bacteriaStreptococcus thermophilusandLactobacillus delbrueckiisubsp.bulgaricus, we were able, by selecting spontaneously occurring mutants, to change dramatically the metabolic products secreted into the growth medium. These mutants consume substantially more of the lactose, metabolize some of the galactose, and secrete the remaining galactose and most of the glucose back into the milk. This allows production of yoghurt with very low lactose levels and enhanced natural sweetness, because humans perceive glucose as sweeter than either lactose or galactose.

scholarly journals Animal Rennets as Sources of Dairy Lactic Acid Bacteria

2014 ◽  
Vol 80 (7) ◽  
pp. 2050-2061 ◽  
Author(s):  
Margherita Cruciata ◽  
Ciro Sannino ◽  
Danilo Ercolini ◽  
Maria L. Scatassa ◽  
Francesca De Filippis ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Streptococcus Thermophilus ◽  
Species Level ◽  
Lactobacillus Delbrueckii ◽  
Rrna Gene ◽  
Microbial Composition ◽  
Content Type

ABSTRACTThe microbial composition of artisan and industrial animal rennet pastes was studied by using both culture-dependent and -independent approaches. Pyrosequencing targeting the 16S rRNA gene allowed to identify 361 operational taxonomic units (OTUs) to the genus/species level. Among lactic acid bacteria (LAB),Streptococcus thermophilusand some lactobacilli, mainlyLactobacillus crispatusandLactobacillus reuteri, were the most abundant species, with differences among the samples. Twelve groups of microorganisms were targeted by viable plate counts revealing a dominance of mesophilic cocci. All rennets were able to acidify ultrahigh-temperature-processed (UHT) milk as shown by pH and total titratable acidity (TTA). Presumptive LAB isolated at the highest dilutions of acidified milks were phenotypically characterized, grouped, differentiated at the strain level by randomly amplified polymorphic DNA (RAPD)-PCR analysis, and subjected to 16S rRNA gene sequencing. Only 18 strains were clearly identified at the species level, asEnterococcus casseliflavus,Enterococcus faecium,Enterococcus faecalis,Enterococcus lactis,Lactobacillus delbrueckii, andStreptococcus thermophilus, while the other strains, all belonging to the genusEnterococcus, could not be allotted into any previously described species. The phylogenetic analysis showed that these strains might represent different unknown species. All strains were evaluated for their dairy technological performances. All isolates produced diacetyl, and 10 of them produced a rapid pH drop in milk, but only 3 isolates were also autolytic. This work showed that animal rennet pastes can be sources of LAB, mainly enterococci, that might contribute to the microbial diversity associated with dairy productions.

scholarly journals Distribution and Functions of Phosphotransferase System Genes in the Genome of the Lactic Acid Bacterium Oenococcus oeni

2013 ◽  
Vol 79 (11) ◽  
pp. 3371-3379 ◽  
Author(s):  
Zohra Jamal ◽  
Cécile Miot-Sertier ◽  
François Thibau ◽  
Lucie Dutilh ◽  
Aline Lonvaud-Funel ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacterium ◽  
Oenococcus Oeni ◽  
Phosphotransferase System ◽  
Content Type ◽  
Low Concentrations ◽  
Perfect Adaptation ◽  
Form Part ◽  
Genes Encoding ◽  
Enzyme I

ABSTRACTOenococcus oeni, the lactic acid bacterium primarily responsible for malolactic fermentation in wine, is able to grow on a large variety of carbohydrates, but the pathways by which substrates are transported and phosphorylated in this species have been poorly studied. We show that the genes encoding the general phosphotransferase proteins, enzyme I (EI) and histidine protein (HPr), as well as 21 permease genes (3 isolated ones and 18 clustered into 6 distinct loci), are highly conserved among the strains studied and may form part of theO. oenicore genome. Additional permease genes differentiate the strains and may have been acquired or lost by horizontal gene transfer events. The coreptsgenes are expressed, and permease gene expression is modulated by the nature of the bacterial growth substrate. DecryptifiedO. oenicells are able to phosphorylate glucose, cellobiose, trehalose, and mannose at the expense of phosphoenolpyruvate. These substrates are present at low concentrations in wine at the end of alcoholic fermentation. The phosphotransferase system (PTS) may contribute to the perfect adaptation ofO. oenito its singular ecological niche.

scholarly journals Two Gene Clusters Coordinate Galactose and Lactose Metabolism in Streptococcus gordonii

2012 ◽  
Vol 78 (16) ◽  
pp. 5597-5605 ◽  
Author(s):  
Lin Zeng ◽  
Nicole C. Martino ◽  
Robert A. Burne
Keyword(s):  
Gene Clusters ◽  
Selective Advantage ◽  
Streptococcus Gordonii ◽  
Phosphotransferase System ◽  
Content Type ◽  
High Affinity ◽  
Oral Biofilms ◽  
Genes Encoding ◽  
Complex Regulation ◽  
Galactose Utilization

ABSTRACTStreptococcus gordoniiis an early colonizer of the human oral cavity and an abundant constituent of oral biofilms. Two tandemly arranged gene clusters, designatedlacandgal, were identified in theS. gordoniiDL1 genome, which encode genes of the tagatose pathway (lacABCD) and sugar phosphotransferase system (PTS) enzyme II permeases. Genes encoding a predicted phospho-β-galactosidase (LacG), a DeoR family transcriptional regulator (LacR), and a transcriptional antiterminator (LacT) were also present in the clusters. Growth and PTS assays supported that the permease designated EIILactransports lactose and galactose, whereas EIIGaltransports galactose. The expression of the gene for EIIGalwas markedly upregulated in cells growing on galactose. Using promoter-catfusions, a role for LacR in the regulation of the expressions of both gene clusters was demonstrated, and thegalcluster was also shown to be sensitive to repression by CcpA. The deletion oflacTcaused an inability to grow on lactose, apparently because of its role in the regulation of the expression of the genes for EIILac, but had little effect on galactose utilization.S. gordoniimaintained a selective advantage overStreptococcus mutansin a mixed-species competition assay, associated with its possession of a high-affinity galactose PTS, althoughS. mutanscould persist better at low pHs. Collectively, these results support the concept that the galactose and lactose systems ofS. gordoniiare subject to complex regulation and that a high-affinity galactose PTS may be advantageous whenS. gordoniiis competing against the caries pathogenS. mutansin oral biofilms.

Characterization of the C-terminal extension of carboxysomal carbonic anhydrase from Synechocystis sp. PCC6803

2002 ◽  
Vol 29 (3) ◽  
pp. 183 ◽  
Author(s):  
Anthony K.-C. So ◽  
Swan S.-W. Cot ◽  
George S. Espie
Keyword(s):  
Carbonic Anhydrase ◽  
Protein Interaction ◽  
Recombinant Dna ◽  
Carbonic Anhydrases ◽  
Recombinant Dna Technology ◽  
Higher Plant ◽  
High Sequence Identity ◽  
Synechocystis Pcc6803 ◽  
Plant Enzymes ◽  
Genes Encoding

Sequence analysis of the carboxysomal carbonic anhydrase (CcaA) from Synechocystis PCC6803, Synechococcus PCC7942 and Nostoc ATCC29133, indicated high sequence identity to the β class of plant and bacterial carbonic anhydrases (CA), and conservation of the active site region. However, the cyanobacterial enzyme has a C-terminal extension of about 75 amino acids (aa) not found in the plant enzymes, and largely absent from other bacterial enzymes. Using recombinant DNA technology, genes encoding C-terminal truncation products of up to 127 aa were overexpressed in E. coli, and partially purified lysates were analysed for CA-mediated exchange of 18O between 13C18O2and H216O. Recombinant CcaA proteins with up to 60 aa removed (CcaAΔ60) were catalytically competent, but beyond this there was an abrupt loss of activity. CcaAΔ0, along with CcaAΔ40 and CcaAΔ60, also catalysed the hydrolysis of carbon oxysulfide (COS; an isoelectronic structural analogue of CO2), but CcaAΔ63 and CcaAΔ127 did not, indicating that truncations greater than 62 aa resulted in a general loss of catalytic competency. Analysis of protein-protein interaction using the yeast two-hybrid system revealed that CcaA did not interact with the large or small Rubisco subunits (RbcL and RbcS, respectively) of Synechocystis, but there was strong CcaA-CcaA interaction. This protein interaction also ceased with C-terminal truncations in CcaA greater than 60 aa. The correlation between loss of CcaA-CcaA interaction and CcaA catalytic activity suggests that the proximal portion of the C-terminal extension is required for oligomerization, and that this oligomerization is essential for catalysis by the cyanobacterial enzyme. Thus, the C-terminal extension may play an important role in the function of CA within cyanobacterial carboxysomes, which is not required by the higher plant enzymes.

scholarly journals Physiological Study of Lactobacillus delbrueckii subsp. bulgaricus Strains in a Novel Chemically Defined Medium

2000 ◽  
Vol 66 (12) ◽  
pp. 5306-5311 ◽  
Author(s):  
Christian Chervaux ◽  
S. Dusko Ehrlich ◽  
Emmanuelle Maguin
Keyword(s):  
Carbon Sources ◽  
Streptococcus Thermophilus ◽  
Defined Medium ◽  
Lactobacillus Delbrueckii ◽  
Protein Labeling ◽  
Chemically Defined Medium ◽  
Phosphotransferase System ◽  
Nutritional Conditions ◽  
Labeling Method

ABSTRACT We developed a chemically defined medium called milieu proche du lait (MPL), in which 22 Lactobacillus delbrueckii subsp.bulgaricus (L. bulgaricus) strains exhibited growth rates ranging from 0.55 to 1 h−1. MPL can also be used for cultivation of other lactobacilli and Streptococcus thermophilus. The growth characteristics of L. bulgaricus in MPL containing different carbon sources were determined, including an initial characterization of the phosphotransferase system transporters involved. For the 22 tested strains, growth on lactose was faster than on glucose, mannose, and fructose. Lactose concentrations below 0.4% were limiting for growth. We isolated 2-deoxyglucose-resistant mutants from strains CNRZ397 and ATCC 11842. CNRZ397-derived mutants were all deficient for glucose, fructose, and mannose utilization, indicating that these three sugars are probably transported via a unique mannose-specific-enzyme-II-like transporter. In contrast, mutants of ATCC 11842 exhibited diverse phenotypes, suggesting that multiple transporters may exist in that strain. We also developed a protein labeling method and verified that exopolysaccharide production and phage infection can occur in MPL. The MPL medium should thus be useful in conducting physiological studies ofL. bulgaricus and other lactic acid bacteria under well controlled nutritional conditions.

Antibiotic susceptibility of different lactic acid bacteria strains

2011 ◽  
Vol 2 (4) ◽  
pp. 335-339 ◽  
Author(s):  
N. Karapetkov ◽  
R. Georgieva ◽  
N. Rumyan ◽  
E. Karaivanova
Keyword(s):  
Cell Wall ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Lactobacillus Acidophilus ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Helveticus ◽  
Lactobacillus Delbrueckii ◽  
Cell Wall Synthesis ◽  
High Susceptibility ◽  
Lactobacillus Delbrueckii Subsp

Five lactic acid bacteria (LAB) strains belonging to species Lactobacillus acidophilus, Lactobacillus helveticus, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus delbrueckii subsp. lactis and Streptococcus thermophilus were tested for their susceptibility to 27 antibiotics. The minimum inhibitory concentrations of each antimicrobial were determined using a microdilution test. Among the strains a high susceptibility was detected for most of the cell-wall synthesis inhibitors (penicillins, cefoxitin and vancomycin) and resistance toward inhibitors of DNA synthesis (trimethoprim/sulfonamides and fluoroquinolones). Generally, the Lactobacillus strains were inhibited by antibiotics such as chloramphenicol, erythromycin and tetracycline at breakpoint levels lower or equal to the levels defined by the European Food Safety Authority. Despite the very similar profile of S. thermophilus LC201 to lactobacilli, the detection of resistance toward erythromycin necessitates the performance of additional tests in order to prove the absence of transferable resistance genes.

scholarly journals Dynamic Changes of Intracellular pH in Individual Lactic Acid Bacterium Cells in Response to a Rapid Drop in Extracellular pH

2000 ◽  
Vol 66 (6) ◽  
pp. 2330-2335 ◽  
Author(s):  
Henrik Siegumfeldt ◽  
K. Björn Rechinger ◽  
Mogens Jakobsen
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Lactic Acid Bacterium ◽  
Intracellular Ph ◽  
Membrane Filter ◽  
Single Cells ◽  
Streptococcus Thermophilus ◽  
Extracellular Ph ◽  
Lactobacillus Delbrueckii ◽  
Rapid Drop

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.

Nerve-Derived Trophic Factors and DNA Elements Controlling Expression of Genes Encoding Synaptic Proteins in Skeletal Muscle Fibers

1998 ◽  
Vol 23 (4) ◽  
pp. 366-376 ◽  
Author(s):  
Bernard J. Jasmin ◽  
Anthony O. Gramolini ◽  
Feisal A. Adatia ◽  
Lindsay Angus ◽  
Céline Boudreau-Larivière ◽  
...  
Keyword(s):  
Neuromuscular Junction ◽  
Transcriptional Activation ◽  
Recombinant Dna ◽  
Signal Transduction Pathway ◽  
Regulatory Elements ◽  
Postsynaptic Membrane ◽  
Synaptic Proteins ◽  
Trophic Factors ◽  
Recombinant Dna Technology ◽  
Genes Encoding

The neuromuscular junction represents an excellent model system for studying various critical issues in neurobiology at the molecular, cellular, and physiological levels. Our understanding of the basic events underlying synpase formation, maintenance, and plasticity has progressed considerably over the last few years primarily because of the numerous studies that have focused on this synapse and used sophisticated recombinant DNA technology. Recent data indicate that myonuclei located in the vicinity of the postsynaptic membrane are in a differential state of transcription compared to nuclei of the extrasynaptic sarcoplasm. Thus, renewal of postsynaptic membrane proteins appears to occur via a mechanism involving the local transcriptional activation of genes encoding these specialized proteins and extracellular cues originating from motoneurons. Such interaction between presynaptic nerve terminals and the postsynaptic sarcoplasm indicates that the entire signal transduction pathway is compartmentalized at the level of the neuromuscular junction. Expression of these genes appears less coregulated than originally anticipated, indicating that maintenance of the postsynaptic membrane requires the contribution of multiple extracellular signals, which ultimately urge target transcription factors to distinct DNA regulatory elements via various second messenger systems. Key words: neuromuscular junction, synapse, acetylcholinesterase, utrophin, agrin, CGRP, promoter, mRNA

scholarly journals Investigation of antimicrobial activity of polyphenol-enriched extracts against probiotic lactic acid bacteria

2019 ◽  
Vol 2 (1) ◽  
pp. 67
Author(s):  
Milena Dimitrova ◽  
Galin Ivanov ◽  
Kiril Mihalev ◽  
Alexander Slavchev ◽  
Ivelina Ivanova ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Food Industry ◽  
Lactobacillus Rhamnosus ◽  
Streptococcus Thermophilus ◽  
Starter Cultures ◽  
Lactobacillus Delbrueckii ◽  
Industrial Plant ◽  
Probiotic Lactic Acid Bacteria ◽  
By Products

The antimicrobial activity of polyphenol-enriched extracts from industrial plant by-products (strawberry and bilberry press residues and distilled rose petals) against probiotic lactic acid bacteria (Lactobacillus delbrueckii subsp. bulgaricus – S10 and S19; Lactobacillus rhamnosus – YW and S25; Lactobacillus gasseri – S20; Streptococcus thermophilus – S13 and S32) was investigated. The minimum inhibitory concentration (MIC) in most strains tested was found to be relatively high (from 6.25 mg.mL-1 to 12.50 mg.mL-1). The maximum concentration of polyphenols without inhibitory effect (MCWI) ranges from 0.390mg.mL-1 to 0.781mg.mL-1. The results obtained in the present study showed that among the tested lactic acid bacteria Lactobacillus delbrueckii subsp. bulgaricus – S19, Lactobacillus rhamnosus – YW and Streptococcus thermophilus – S13 had the best growth characteristics in polyphenol-enriched culture medium. These strains had the highest MIC and MCWI values and could be used as starter cultures for polyphenol-fortified fermented milks. Practical applications: The use of polyphenol-enriched extracts from industrial plant by-products (waste) – distilled rose petals (by-products of rose oil production) and strawberry and bilberry press residues (by-products of fruit juice production) contribute for improving the economic effect and for solving environmental problems in food industry. Development of functional fermented milks with combination of probiotic starter cultures and polyphenol extracts is current and perspective direction of food industry.

scholarly journals Aprovechamiento de ñame espino post-cosecha (Dioscorea rotundata P.) en la extracción de ácido láctico/Use of post-harvest hawthorn yam (Dioscorea rotundata P.) in the extraction of lactic acid

Prospectiva ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 76-82
Author(s):  
Ronald Eduardo Tejada Tovar ◽  
Candelaria Nahir Tejada Tovar ◽  
Lesly Patricia Tejeda Benitez ◽  
Angel Villabona Ortiz ◽  
Clemente Granados Conde
Keyword(s):  
Lactic Acid ◽  
Streptococcus Thermophilus ◽  
Lactobacillus Delbrueckii ◽  
Dioscorea Rotundata ◽  
Post Harvest

El objetivo del presente estudio fue obtener ácido láctico (AL) a partir del almidón de ñame espino post-cosecha (Dioscorea rotundata) mediante fermentación del almidón usando Lactobacillus delbrueckii ssp. bulgaricus y Streptococcus thermophilus a 37 ºC. Se lavaron 5 Kg de tubérculos frescos, descortezaron, redujo de tamaño, licuó y filtró; el filtrado se decantó lavándose el sedimento con agua destilada, filtrados al vacío y secados a 60 ºC por 12 h, seguido de molienda para su posterior empaque. El almidón se caracterizó determinando el contenido de fibra cruda, cenizas, grasa, proteínas, humedad residual y amilosa. El porcentaje de AL se determinó por titulación de 100 mL de muestra fermentada con NaOH usando fenolftaleína como indicador y la concentración se midió por cromatografía. Se obtuvo un almidón con porcentajes de 78,46, 26,78 y 73,22 % de carbohidratos totales, amilosa y amilopectina, respetivamente. Se encontró que el pH afecta significativamente las actividades enzimáticas y la asimilación de nutrientes por parte de los microorganismos utilizados y que la fermentación del almidón de ñame con los microorganismos seleccionados produjo un 16,26% de AL. Se concluye que el AL puede ser obtenido a partir del almidón de D. rotundata.

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