scholarly journals An l-Fucose Operon in the Probiotic Lactobacillus rhamnosus GG Is Involved in Adaptation to Gastrointestinal Conditions

2015 ◽  
Vol 81 (11) ◽  
pp. 3880-3888 ◽  
Author(s):  
Jimmy E. Becerra ◽  
María J. Yebra ◽  
Vicente Monedero
Keyword(s):  
Carbon Catabolite Repression ◽  
Lactobacillus Rhamnosus ◽  
Transcriptional Analysis ◽  
Growth Defect ◽  
Wild Type ◽  
Lactobacillus Rhamnosus Gg ◽  
Content Type ◽  
Gastrointestinal Conditions ◽  
In The Wild ◽  
The Many

ABSTRACTl-Fucose is a sugar present in human secretions as part of human milk oligosaccharides, mucins, and other glycoconjugates in the intestinal epithelium. The genome of the probioticLactobacillus rhamnosusGG (LGG) carries a gene cluster encoding a putativel-fucose permease (fucP),l-fucose catabolic pathway (fucI,fucK,fucU, andfucA), and a transcriptional regulator (fucR). The metabolism ofl-fucose in LGG results in 1,2-propanediol production, and theirfucIandfucPmutants displayed a severe and mild growth defect onl-fucose, respectively. Transcriptional analysis revealed that thefucgenes are induced byl-fucose and subject to a strong carbon catabolite repression effect. This induction was triggered by FucR, which acted as a transcriptional activator necessary for growth onl-fucose. LGG utilized fucosyl-α1,3-N-acetylglucosamine and contrarily to other lactobacilli, the presence offucgenes allowed this strain to use thel-fucose moiety. InfucIandfucRmutants, but not infucPmutant,l-fucose was not metabolized and it was excreted to the medium during growth on fucosyl-α1,3-N-acetylglucosamine. Thefucgenes were induced by this fucosyl-disaccharide in the wild type and thefucPmutant but not in afucImutant, showing that FucP does not participate in the regulation offucgenes and thatl-fucose metabolism is needed for FucR activation. Thel-fucose operon characterized here constitutes a new example of the many factors found in LGG that allow this strain to adapt to the gastrointestinal conditions.

scholarly journals Development of a Markerless Gene Replacement System for Acidithiobacillus ferrooxidans and Construction of apfkBMutant

2011 ◽  
Vol 78 (6) ◽  
pp. 1826-1835 ◽  
Author(s):  
Huiyan Wang ◽  
Xiangmei Liu ◽  
Shuangshuang Liu ◽  
Yangyang Yu ◽  
Jianqun Lin ◽  
...  
Keyword(s):  
Acidithiobacillus Ferrooxidans ◽  
Homing Endonuclease ◽  
Metallurgical Industry ◽  
Gene Replacement ◽  
Transcriptional Analysis ◽  
Wild Type ◽  
Content Type ◽  
Functional Studies ◽  
In The Wild ◽  
K 12

ABSTRACTThe extremely acidophilic, chemolithoautotrophicAcidithiobacillus ferrooxidansis an important bioleaching bacterium of great value in the metallurgical industry and environmental protection. In this report, a mutagenesis system based on the homing endonuclease I-SceI was developed to produce targeted, unmarked gene deletions in the strainA. ferrooxidansATCC 23270. A targeted phosphofructokinase (PFK) gene (pfkB) mutant ofA. ferrooxidansATCC 23270 was constructed by homologous recombination and identified by PCR with specific primers as well as Southern blot analysis. This potentialpfkBgene (AFE_1807) was also characterized by expression in PFK-deficientEscherichia colicells, and heteroexpression of the PFKB protein demonstrated that it had functional PFK activity, though it was significantly lower (about 800-fold) than that of phosphofructokinase-2 (PFK-B) expressed by thepfkBgene fromE. coliK-12. The function of the potential PFKB protein inA. ferrooxidanswas demonstrated by comparing the properties of thepfkBmutant with those of the wild type. ThepfkBmutant strain displayed a relatively reduced growth capacity in S0medium (0.5% [wt/vol] elemental sulfur in 9K basal salts solution adjusted to pH 3.0 with H2SO4), but the mutation did not completely preventA. ferrooxidansfrom assimilating exogenous glucose. The transcriptional analysis of some related genes in central carbohydrate metabolism in the wild-type and mutant strains with or without supplementation of glucose was carried out by quantitative reverse transcription-PCR. This report suggests that the markerless mutagenesis strategy could serve as a model for functional studies of other genes of interest fromA. ferrooxidansand multiple mutations could be made in a singleA. ferrooxidansstrain.

scholarly journals Oxygen-Inducible Conversion of Lactate to Acetate in Heterofermentative Lactobacillus brevis ATCC 367

2017 ◽  
Vol 83 (21) ◽  
Author(s):  
Tingting Guo ◽  
Li Zhang ◽  
Yongping Xin ◽  
ZhenShang Xu ◽  
Huiying He ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactobacillus Brevis ◽  
Transcriptional Analysis ◽  
Wild Type ◽  
Content Type ◽  
Aerobic Stability ◽  
In The Wild ◽  
Acetate Accumulation ◽  
Yeasts And Molds ◽  
The Impact

ABSTRACT Lactobacillus brevis is an obligatory heterofermentative lactic acid bacterium that produces high levels of acetate, which improve the aerobic stability of silages against deterioration caused by yeasts and molds. However, the mechanism involved in acetate accumulation has yet to be elucidated. Here, experimental evidence indicated that aerobiosis resulted in the conversion of lactate to acetate after glucose exhaustion in L. brevis ATCC 367 (GenBank accession number NC_008497 ). To elucidate the conversion pathway, in silico analysis showed that lactate was first converted to pyruvate by the reverse catalytic reaction of lactate dehydrogenase (LDH); subsequently, pyruvate conversion to acetate might be mediated by pyruvate dehydrogenase (PDH) or pyruvate oxidase (POX). Transcriptional analysis indicated that the pdh and pox genes of L. brevis ATCC 367 were upregulated 37.92- and 18.32-fold, respectively, by oxygen and glucose exhaustion, corresponding to 5.32- and 2.35-fold increases in the respective enzyme activities. Compared with the wild-type strain, the transcription and enzymatic activity of PDH remained stable in the Δpox mutant, while those of POX increased significantly in the Δpdh mutant. More lactate but less acetate was produced in the Δpdh mutant than in the wild-type and Δpox mutant strains, and more H2O2 (a product of the POX pathway) was produced in the Δpdh mutant. We speculated that the high levels of aerobic acetate accumulation in L. brevis ATCC 367 originated mainly from the reuse of lactate to produce pyruvate, which was further converted to acetate by the predominant and secondary functions of PDH and POX, respectively. IMPORTANCE PDH and POX are two possible key enzymes involved in aerobic acetate accumulation in lactic acid bacteria (LAB). It is currently thought that POX plays the major role in aerobic growth in homofermentative LAB and some heterofermentative LAB, while the impact of PDH remains unclear. In this study, we reported that both PDH and POX worked in the aerobic conversion of lactate to acetate in L. brevis ATCC 367, in dominant and secondary roles, respectively. Our findings will further develop the theory of aerobic metabolism by LAB.

scholarly journals WblAch, a Pivotal Activator of Natamycin Biosynthesis and Morphological Differentiation in Streptomyces chattanoogensis L10, Is Positively Regulated by AdpAch

2014 ◽  
Vol 80 (22) ◽  
pp. 6879-6887 ◽  
Author(s):  
Pin Yu ◽  
Shui-Ping Liu ◽  
Qing-Ting Bu ◽  
Zhen-Xing Zhou ◽  
Zhen-Hong Zhu ◽  
...  
Keyword(s):  
Morphological Differentiation ◽  
Binding Activity ◽  
Transcriptional Analysis ◽  
Antibiotic Biosynthesis ◽  
Content Type ◽  
Real Time Quantitative Pcr ◽  
Dna Binding Activity ◽  
In The Wild ◽  
Natamycin Production ◽  
Streptomyces Chattanoogensis

ABSTRACTDetailed mechanisms ofWhiB-like (Wbl) proteins involved in antibiotic biosynthesis and morphological differentiation are poorly understood. Here, we characterize the role of WblAch, aStreptomyces chattanoogensisL10 protein belonging to this superfamily. Based on DNA microarray data and verified by real-time quantitative PCR (qRT-PCR), the expression ofwblAchwas shown to be positively regulated by AdpAch. Gel retardation assays and DNase I footprinting experiments showed that AdpAchhas specific DNA-binding activity for the promoter region ofwblAch. Gene disruption and genetic complementation revealed that WblAchacts in a positive manner to regulate natamycin production. WhenwblAchwas overexpressed in the wild-type strain, the natamycin yield was increased by ∼30%. This provides a strategy to generate improved strains for natamycin production. Moreover, transcriptional analysis showed that the expression levels ofwhigenes (includingwhiA,whiB,whiH, andwhiI) were severely depressed in the ΔwblAchmutant, suggesting that WblAchplays a part in morphological differentiation by influencing the expression of thewhigenes.

scholarly journals Abrogation of Neuraminidase Reduces Biofilm Formation, Capsule Biosynthesis, and Virulence of Porphyromonas gingivalis

2011 ◽  
Vol 80 (1) ◽  
pp. 3-13 ◽  
Author(s):  
Chen Li ◽  
Kurniyati ◽  
Bo Hu ◽  
Jiang Bian ◽  
Jianlan Sun ◽  
...  
Keyword(s):  
Porphyromonas Gingivalis ◽  
Biofilm Formation ◽  
Adult Population ◽  
Transcriptional Analysis ◽  
Wild Type ◽  
Content Type ◽  
Multiple Organs ◽  
Biochemical Analyses

ABSTRACTThe oral bacteriumPorphyromonas gingivalisis a key etiological agent of human periodontitis, a prevalent chronic disease that affects up to 80% of the adult population worldwide.P. gingivalisexhibits neuraminidase activity. However, the enzyme responsible for this activity, its biochemical features, and its role in the physiology and virulence ofP. gingivalisremain elusive. In this report, we found thatP. gingivalisencodes a neuraminidase, PG0352 (SiaPg). Transcriptional analysis showed thatPG0352is monocistronic and is regulated by a sigma70-like promoter. Biochemical analyses demonstrated that SiaPgis an exo-α-neuraminidase that cleaves glycosidic-linked sialic acids. Cryoelectron microscopy and tomography analyses revealed that thePG0352deletion mutant (ΔPG352) failed to produce an intact capsule layer. Compared to the wild type,in vitrostudies showed that ΔPG352 formed less biofilm and was less resistant to killing by the host complement.In vivostudies showed that while the wild type caused a spreading type of infection that affected multiple organs and all infected mice were killed, ΔPG352 only caused localized infection and all animals survived. Taken together, these results demonstrate that SiaPgis an important virulence factor that contributes to the biofilm formation, capsule biosynthesis, and pathogenicity ofP. gingivalis, and it can potentially serve as a new target for developing therapeutic agents againstP. gingivalisinfection.

scholarly journals Survival of Lactobacillus rhamnosus GG during Simulated Gastrointestinal Conditions Depending on Food Matrix

2016 ◽  
Vol 5 (5) ◽  
pp. 56 ◽  
Author(s):  
Riin Karu ◽  
Ingrid Sumeri
Keyword(s):  
Whey Protein ◽  
Apple Juice ◽  
Negative Impact ◽  
Physiological State ◽  
Lactobacillus Rhamnosus ◽  
Maximum Growth ◽  
Food Matrix ◽  
Lactobacillus Rhamnosus Gg ◽  
Significant Drop ◽  
Gastrointestinal Conditions

When developing new probiotic foods, their protective properties in maintaining viability of probiotics under gastrointestinal conditions should be evaluated. In the current study, human upper gastrointestinal tract simulator (GITS) was used to compare the effect of different food matrixes on the survival of Lactobacillus rhamnosus GG (LGG). pH-auxostat was chosen for the cultivation of LGG cells to obtain culture samples in the same physiological state at maximum growth rate for the GITS experiments. The LGG culture was centrifuged and fast frozen in liquid nitrogen in various liquid food matrixes (commercial UHT milk, soymilk, apple juice, titrated apple juice, whey protein powder drink and M.R.S. Broth as reference) and stored at -400C. During 3-month storage, reduction of viability was significant only for apple juice. In the GITS experiments, bile had a greater negative impact on LGG than acid conditions, also the effect of food matrix was noted - in the case of milk, soymilk and whey protein powder drink only the highest concentration of bile (0.4%) caused a significant drop in the viability of bacteria when compared to apple juice. To maximize the health benefits of foodstuffs, it should be taken into account that the survival of probiotics during fast freezing, storage and gastrointestinal passage is dependent on the food matrix.

scholarly journals Activation of 2,4-Diaminoquinazoline in Mycobacterium tuberculosis by Rv3161c, a Putative Dioxygenase

2018 ◽  
Vol 63 (1) ◽  
Author(s):  
Eduard Melief ◽  
Shilah A. Bonnett ◽  
Edison S. Zuniga ◽  
Tanya Parish
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Mutant Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Type A ◽  
Wild Type ◽  
Metabolite Analysis ◽  
Content Type ◽  
Data Support ◽  
In The Wild

ABSTRACT The diaminoquinazoline series has good potency against Mycobacterium tuberculosis. Resistant isolates have mutations in Rv3161c, a putative dioxygenase. We carried out metabolite analysis on a wild-type strain and an Rv3161c mutant strain after exposure to a diaminoquinazoline. The parental compound was found in intracellular extracts from the mutant but not the wild type. A metabolite consistent with a monohydroxylated form was identified in the wild type. These data support the hypothesis that Rv3161c metabolizes diaminoquinazolines in M. tuberculosis.

scholarly journals Identification of different putative outer membrane electron conduits necessary for Fe(III) citrate, Fe(III) oxide, Mn(IV) oxide, or electrode reduction by Geobacter sulfurreducens

2017 ◽  
Author(s):  
Fernanda Jiménez Otero ◽  
Chi Ho Chan ◽  
Daniel R. Bond
Keyword(s):  
Electron Transfer ◽  
Outer Membrane ◽  
Electron Acceptor ◽  
Single Gene ◽  
Gene Clusters ◽  
Geobacter Sulfurreducens ◽  
Transcriptional Analysis ◽  
Growth Defect ◽  
Redox Potentials ◽  
Wild Type

AbstractAt least five gene clusters in the Geobacter sulfurreducens genome encode putative ‘electron conduits’ implicated in electron transfer across the outer membrane, each containing a periplasmic multiheme c-type cytochrome, integral outer membrane anchor, and outer membrane redox lipoprotein(s). Markerless single gene cluster deletions and all possible multiple deletion combinations were constructed and grown with soluble Fe(III) citrate, Fe(III)- and Mn(IV)-oxides, and graphite electrodes poised at +0.24 V and −0.1 V vs. SHE. Different gene clusters were necessary for reduction of each electron acceptor. During metal oxide reduction, deletion of the previously described omcBC cluster caused defects, but deletion of additional components in an ΔomcBC background, such as extEFG, were needed to produce defects greater than 50% compared to wild type. Deletion of all five gene clusters abolished all metal reduction. During electrode reduction, only the ΔextABCD mutant had a severe growth defect at both redox potentials, while this mutation did not affect Fe(III)-oxide, Mn(IV)-oxide, or Fe(III) citrate reduction. Some mutants containing only one cluster were able to reduce particular terminal electron acceptors better than wild type, suggesting routes for improvement by targeting specific electron transfer pathways. Transcriptomic comparisons between fumarate and electrode-based growth showed all of these ext clusters to be constitutive, and transcriptional analysis of the triple-deletion strain containing only extABCD detected no significant changes in expression of known redox proteins or pili components. These genetic experiments reveal new outer membrane conduit complexes necessary for growth of G. sulfurreducens, depending on the available extracellular electron acceptor.

scholarly journals Identification of different putative outer membrane electron conduits necessary for Fe(III) citrate, Fe(III)-oxide, Mn(IV)-oxide, or electrode reduction by Geobacter sulfurreducens .

2018 ◽  
Author(s):  
Fernanda Jiménez Otero ◽  
Chi Ho Chan ◽  
Daniel R Bond
Keyword(s):  
Electron Transfer ◽  
Outer Membrane ◽  
Electron Acceptor ◽  
Single Gene ◽  
Gene Clusters ◽  
Geobacter Sulfurreducens ◽  
Transcriptional Analysis ◽  
Growth Defect ◽  
Redox Potentials ◽  
Wild Type

At least five gene clusters in the Geobacter sulfurreducens genome encode putative ‘electron conduits’ implicated in electron transfer across the outer membrane, each containing a periplasmic multiheme c -type cytochrome, integral outer membrane anchor, and outer membrane redox lipoprotein(s). Markerless single gene cluster deletions and all possible multiple deletion combinations were constructed and grown with soluble Fe(III) citrate, Fe(III)- and Mn(IV)-oxides, and graphite electrodes poised at +0.24 V and -0.1 V vs. SHE. Different gene clusters were necessary for reduction of each electron acceptor. During metal oxide reduction, deletion of the previously described omcBC cluster caused defects, but deletion of additional components in an Δ omcBC background, such as extEFG , were needed to produce defects greater than 50% compared to wild type. Deletion of all five gene clusters abolished all metal reduction. During electrode reduction, only the Δ extABCD mutant had a severe growth defect at both redox potentials, while this mutation did not affect Fe(III)-oxide, Mn(IV)-oxide, or Fe(III) citrate reduction. Some mutants containing only one cluster were able to reduce particular terminal electron acceptors better than wild type, suggesting routes for improvement by targeting specific electron transfer pathways. Transcriptomic comparisons between fumarate and electrode-based growth showed all of these ext clusters to be constitutive, and transcriptional analysis of the triple-deletion strain containing only extABCD detected no significant changes in expression of known redox proteins or pili components. These genetic experiments reveal new outer membrane conduit complexes necessary for growth of G. sulfurreducens , depending on the available extracellular electron acceptor.

Intake of Lactobacillus rhamnosus GG (LGG) fermented milk before drinking alcohol reduces acetaldehyde levels and duration of flushing in drinkers with wild-type and heterozygous mutant ALDH2: a randomized, blinded crossover controlled trial

2021 ◽  
Author(s):  
Dunyaporn Trachootham ◽  
Kanyawee Whanmek ◽  
Kemika Praengam ◽  
Piya Temviriyanukul ◽  
Chalat Santivarangkna
Keyword(s):  
Alcohol Consumption ◽  
Alcohol Intake ◽  
Controlled Trial ◽  
Lactobacillus Rhamnosus ◽  
Fermented Milk ◽  
Wild Type ◽  
Drinking Alcohol ◽  
Aldehyde Dehydrogenase 2 ◽  
Lactobacillus Rhamnosus Gg ◽  
Aldehyde Dehydrogenase 2 Gene

Alcohol consumption leads to acetaldehyde accumulation which is carcinogenic. Drinking LGG fermented milk before alcohol intake reduces blood and salivary acetaldehyde levels especially in people with mutant aldehyde dehydrogenase 2 gene (ALDH2).

scholarly journals Spermidine Inversely Influences Surface Interactions and Planktonic Growth in Agrobacterium tumefaciens

2016 ◽  
Vol 198 (19) ◽  
pp. 2682-2691 ◽  
Author(s):  
Yi Wang ◽  
Sok Ho Kim ◽  
Ramya Natarajan ◽  
Jason E. Heindl ◽  
Eric L. Bruger ◽  
...  
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Biofilm Formation ◽  
Direct Synthesis ◽  
Wild Type ◽  
Cyclic Diguanylate ◽  
Content Type ◽  
Exogenous Addition ◽  
In The Wild ◽  
Growth Requirement ◽  
Transposon Insertions

ABSTRACTIn bacteria, the functions of polyamines, small linear polycations, are poorly defined, but these metabolites can influence biofilm formation in several systems. Transposon insertions in an ornithine decarboxylase (odc) gene inAgrobacterium tumefaciens, predicted to direct synthesis of the polyamine putrescine from ornithine, resulted in elevated cellulose. Null mutants forodcgrew somewhat slowly in a polyamine-free medium but exhibited increased biofilm formation that was dependent on cellulose production. Spermidine is an essential metabolite inA. tumefaciensand is synthesized from putrescine inA. tumefaciensvia the stepwise actions of carboxyspermidine dehydrogenase (CASDH) and carboxyspermidine decarboxylase (CASDC). Exogenous addition of either putrescine or spermidine to theodcmutant returned biofilm formation to wild-type levels. Low levels of exogenous spermidine restored growth to CASDH and CASDC mutants, facilitating weak biofilm formation, but this was dampened with increasing concentrations. Norspermidine rescued growth for theodc, CASDH, and CASDC mutants but did not significantly affect their biofilm phenotypes, whereas in the wild type, it stimulated biofilm formation and depressed spermidine levels. Theodcmutant produced elevated levels of cyclic diguanylate monophosphate (c-di-GMP), exogenous polyamines modulated these levels, and expression of a c-di-GMP phosphodiesterase reversed the enhanced biofilm formation. Prior work revealed accumulation of the precursors putrescine and carboxyspermidine in the CASDH and CASDC mutants, respectively, but unexpectedly, both mutants accumulated homospermidine; here, we show that this requires a homospermidine synthase (hss) homologue.IMPORTANCEPolyamines are small, positively charged metabolites that are nearly ubiquitous in cellular life. They are often essential in eukaryotes and more variably in bacteria. Polyamines have been reported to influence the surface-attached biofilm formation of several bacteria. InAgrobacterium tumefaciens, mutants with diminished levels of the polyamine spermidine are stimulated for biofilm formation, and exogenous provision of spermidine decreases biofilm formation. Spermidine is also essential forA. tumefaciensgrowth, but the related polyamine norspermidine exogenously rescues growth and does not diminish biofilm formation, revealing that the growth requirement and biofilm control are separable. Polyamine control of biofilm formation appears to function via effects on the cellular second messenger cyclic diguanylate monophosphate, regulating the transition from a free-living to a surface-attached lifestyle.

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