scholarly journals Transcriptome profile of carbon catabolite repression in an efficient l-(+)-lactic acid-producing bacterium Enterococcus mundtii QU25 grown in media with combinations of cellobiose, xylose, and glucose

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0242070
Author(s):  
Yuh Shiwa ◽  
Haruko Fujiwara ◽  
Mao Numaguchi ◽  
Mohamed Ali Abdel-Rahman ◽  
Keisuke Nabeta ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Pentose Phosphate Pathway ◽  
Catabolite Repression ◽  
Carbon Catabolite Repression ◽  
Pentose Phosphate ◽  
Exponential Growth Phase ◽  
Xylose Metabolism ◽  
Lignocellulosic Hydrolysates ◽  
Enterococcus Mundtii ◽  
In Cells

Enterococcus mundtii QU25, a non-dairy lactic acid bacterium of the phylum Firmicutes, is capable of simultaneously fermenting cellobiose and xylose, and is described as a promising strain for the industrial production of optically pure l-lactic acid (≥ 99.9%) via homo-fermentation of lignocellulosic hydrolysates. Generally, Firmicutes bacteria show preferential consumption of sugar (usually glucose), termed carbon catabolite repression (CCR), while hampering the catabolism of other sugars. In our previous study, QU25 exhibited apparent CCR in a glucose-xylose mixture phenotypically, and transcriptional repression of the xylose operon encoding initial xylose metabolism genes, likely occurred in a CcpA-dependent manner. QU25 did not exhibit CCR phenotypically in a cellobiose-xylose mixture. The aim of the current study is to elucidate the transcriptional change associated with the simultaneous utilization of cellobiose and xylose. To this end, we performed RNA-seq analysis in the exponential growth phase of E. mundtii QU25 cells grown in glucose, cellobiose, and/or xylose as either sole or co-carbon sources. Our transcriptomic data showed that the xylose operon was weakly repressed in cells grown in a cellobiose-xylose mixture compared with that in cells grown in a glucose-xylose mixture. Furthermore, the gene expression of talC, the sole gene encoding transaldolase, is expected to be repressed by CcpA-mediated CCR. QU25 metabolized xylose without using transaldolase, which is necessary for homolactic fermentation from pentoses using the pentose-phosphate pathway. Hence, the metabolism of xylose in the presence of cellobiose by QU25 may have been due to 1) sufficient amounts of proteins encoded by the xylose operon genes for xylose metabolism despite of the slight repression of the operon, and 2) bypassing of the pentose-phosphate pathway without the TalC activity. Accordingly, we have determined the targets of genetic modification in QU25 to metabolize cellobiose, xylose and glucose simultaneously for application of the lactic fermentation from lignocellulosic hydrolysates.

l-(+)-Lactic acid production by co-fermentation of cellobiose and xylose without carbon catabolite repression using Enterococcus mundtii QU 25

RSC Advances ◽  
2014 ◽  
Vol 4 (42) ◽  
pp. 22013-22021 ◽  
Author(s):  
Ying Wang ◽  
Mohamed Ali Abdel-Rahman ◽  
Yukihiro Tashiro ◽  
Yaotian Xiao ◽  
Takeshi Zendo ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lignocellulosic Biomass ◽  
Production System ◽  
Catabolite Repression ◽  
Acid Production ◽  
Carbon Catabolite Repression ◽  
Lactic Acid Production ◽  
Fed Batch ◽  
Bacterial Cultures ◽  
Enterococcus Mundtii

We established an effective highl-lactic acid production system based on fed-batch bacterial cultures utilising lignocellulosic biomass-derived mixed sugars without carbon catabolite repression.

scholarly journals Homo-d-Lactic Acid Fermentation from Arabinose by Redirection of the Phosphoketolase Pathway to the Pentose Phosphate Pathway in l-Lactate Dehydrogenase Gene-Deficient Lactobacillus plantarum

2009 ◽  
Vol 75 (15) ◽  
pp. 5175-5178 ◽  
Author(s):  
Kenji Okano ◽  
Shogo Yoshida ◽  
Tsutomu Tanaka ◽  
Chiaki Ogino ◽  
Hideki Fukuda ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactate Dehydrogenase ◽  
Lactobacillus Plantarum ◽  
Pentose Phosphate Pathway ◽  
Pentose Phosphate ◽  
Lactic Acid Fermentation ◽  
Acid Fermentation ◽  
Dehydrogenase Gene ◽  
Phosphoketolase Pathway ◽  
Optically Pure

ABSTRACT Optically pure d-lactic acid fermentation from arabinose was achieved by using the Lactobacillus plantarum NCIMB 8826 strain whose l-lactate dehydrogenase gene was deficient and whose phosphoketolase gene was substituted with a heterologous transketolase gene. After 27 h of fermentation, 38.6 g/liter of d-lactic acid was produced from 50 g/liter of arabinose.

Metabolic activities of sheep erythrocytes. I. Glycolytic activities

1962 ◽  
Vol 13 (1) ◽  
pp. 31 ◽  
Author(s):  
RA Leng ◽  
EF Annison
Keyword(s):  
Carbon Dioxide ◽  
Methylene Blue ◽  
Lactic Acid ◽  
Oxygen Uptake ◽  
Pentose Phosphate Pathway ◽  
Glucose Oxidation ◽  
Lactic Acid Production ◽  
Pentose Phosphate ◽  
Sheep Erythrocytes ◽  
Metabolic Activities

Sheep erythrocytes, which in most animals are impermeable to glucose, show low glycolytic activities relative to human cells. When 14C-labelled glucose was incubated with erythrocyte suspensions the oxygen uptake was 10.9 ± 1.8 µl/hr/ml of cells (5 replications), and glucose oxidation (measured by recovery of [14C]carbon dioxide) was 0.03 ± 0.007 µmole/hr/ml (5). Addition of methylene blue (0.4 µmole/ ml) increased oxygen uptake to 56 ± 3.5 µl/hr/ml (5) and glucose oxidation to 0.36 ± 0.02 µmole/hr/ml. Lactic acid production was increased from 1 .5 ± 0.06 µmole/hr/ml (7) to 1.7 ± 0.11 µmole/hr/ml (7) in the presence of methylene blue. Comparison of the yields of [14C]carbon dioxide from [1-14C]glucose and uniformly labelled [14C]glucose indicated that when stimulated by methylene blue 80–100% of glycolysis proceeded by the pentose phosphate pathway, but in the unstimulated system the alternative aerobic pathway accounted for only about 15% of total glycolysis.

scholarly journals Isolation and Characterization of Acid-Tolerant, Thermophilic Bacteria for Effective Fermentation of Biomass-Derived Sugars to Lactic Acid

2006 ◽  
Vol 72 (5) ◽  
pp. 3228-3235 ◽  
Author(s):  
Milind A. Patel ◽  
Mark S. Ou ◽  
Roberta Harbrucker ◽  
Henry C. Aldrich ◽  
Marian L. Buszko ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Pentose Phosphate Pathway ◽  
Thermophilic Bacteria ◽  
Cellulase Activity ◽  
Pentose Phosphate ◽  
Bacterial Strains ◽  
16S Rrna Sequence ◽  
Cost Component ◽  
Isolation And Characterization ◽  
Fungal Cellulase

ABSTRACT Biomass-derived sugars, such as glucose, xylose, and other minor sugars, can be readily fermented to fuel ethanol and commodity chemicals by the appropriate microbes. Due to the differences in the optimum conditions for the activity of the fungal cellulases that are required for depolymerization of cellulose to fermentable sugars and the growth and fermentation characteristics of the current industrial microbes, simultaneous saccharification and fermentation (SSF) of cellulose is envisioned at conditions that are not optimal for the fungal cellulase activity, leading to a higher-than-required cost of cellulase in SSF. We have isolated bacterial strains that grew and fermented both glucose and xylose, major components of cellulose and hemicellulose, respectively, to l(+)-lactic acid at 50�C and pH 5.0, conditions that are also optimal for fungal cellulase activity. Xylose was metabolized by these new isolates through the pentose-phosphate pathway. As expected for the metabolism of xylose by the pentose-phosphate pathway, [13C]lactate accounted for more than 90% of the total 13C-labeled products from [13C]xylose. Based on fatty acid profile and 16S rRNA sequence, these isolates cluster with Bacillus coagulans, although the B. coagulans type strain, ATCC 7050, failed to utilize xylose as a carbon source. These new B. coagulans isolates have the potential to reduce the cost of SSF by minimizing the amount of fungal cellulases, a significant cost component in the use of biomass as a renewable resource, for the production of fuels and chemicals.

scholarly journals 1249. Metabolomic Profile of Heterogeneous Vancomycin-Intermediate Staphylococcus aureus (hVISA) in Latin-American MRSA Isolates

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S713-S714
Author(s):  
Betsy E Castro-Cardozo ◽  
Monica Cala ◽  
Catalina Espitia-Acero ◽  
Rafael Rios ◽  
Lizeth Leon ◽  
...  
Keyword(s):  
Amino Acids ◽  
Latin American ◽  
Stress Responses ◽  
Pentose Phosphate Pathway ◽  
Therapeutic Option ◽  
Mechanistic Model ◽  
Pentose Phosphate ◽  
Exponential Growth Phase ◽  
Metabolomic Profile ◽  
Research Support

Abstract Background Vancomycin (VAN) is a first-line therapeutic option in severe infections caused by MRSA in Latin-America (LA). Development of reduced susceptibility to VAN has been associated with multiple changes in genes encoding pathways for cell wall metabolism and envelope stress responses. Nevertheless, a detailed and coherent mechanistic model to explain the phenotype remains elusive. To gain further insights into the hVISA phenotype, we sought to explore the metabolomic profile of hVISA isolates from LA. Methods The undirected profile of intracellular S. aureus metabolites was analysed in four clinical isolates (two hVISA and two VSSA [Vancomycin susceptible S. aureus]) belonging to the Chilean/Cordobes clone-ST5 (the predominant hVISA lineage in LA), and two reference strains Mu3 and N315. The metabolites were obtained in mid-exponential growth phase in trypticase soy broth in five independent replicates. The metabolites were determined by reverse phase liquid chromatography and hydrophilic interaction. The metabolic profile was determined by variable importance in the projection score (VIP > 1). The differences between hVISA and VSSA were maximized by orthogonal partial least squares discriminant analysis (OPLS-DA) and the affected metabolic pathways were identified with MetaboAnalyst. Results Among the differences identified in the metabolic profiles of hVISA respect to VSSA, 69 metabolites were relevant. Of these, 47 were fatty acids (including glycerol), 7 amino acids and 6 nucleosides (Table 1). These changes mainly impact the biosynthesis of amino acids derived from pyruvate since tyrosine, valine and leucine, had a reduction of 34%, 57% and 41% in hVISA compared to VSSA, respectively, which suggests alterations of the acid cycle tricarboxylic (TCA). Additionally, a reduction in purine and pyrimidine metabolism in hVISA was identified with reduction of nucleosides and dinucleotides derived from the pentose phosphate pathway. Table 1. Metabolites with higher VIP scores in the comparison of the hVISA and VSSA profile Conclusion We were able to observe metabolic alterations in TCA, pentose phosphate pathway and purine intermediates in hVISA-ST5 isolates. Our results support that gluconeogenesis and biosynthesis of carbohydrates and nucleic acids are the main pathways involved in the reduced susceptibility to VAN as reported in VISA isolates. Disclosures Cesar A. Arias, M.D., MSc, Ph.D., FIDSA, Entasis Therapeutics (Grant/Research Support)MeMed Diagnostics (Grant/Research Support)Merk (Grant/Research Support) Lorena Diaz, PhD , Nothing to disclose

scholarly journals trans-Acting Factors Affecting Carbon Catabolite Repression of the hut Operon inBacillus subtilis

1999 ◽  
Vol 181 (9) ◽  
pp. 2883-2888 ◽  
Author(s):  
Jill M. Zalieckas ◽  
Lewis V. Wray ◽  
Susan H. Fisher
Keyword(s):  
Catabolite Repression ◽  
Double Mutant ◽  
Minimal Medium ◽  
Carbon Catabolite Repression ◽  
Regulatory Protein ◽  
Luria Bertani ◽  
Factors Affecting ◽  
Glucose Minimal Medium ◽  
Rates Of Growth ◽  
In Cells

ABSTRACT In Bacillus subtilis, CcpA-dependent carbon catabolite repression (CCR) mediated at several cis-acting carbon repression elements (cre) requires the seryl-phosphorylated form of both the HPr (ptsH) and Crh (crh) proteins. During growth in minimal medium, theptsH1 mutation, which prevents seryl phosphorylation of HPr, partially relieves CCR of several genes regulated by CCR. Examination of the CCR of the histidine utilization (hut) enzymes in cells grown in minimal medium showed that neither theptsH1 nor the crh mutation individually had any affect on hut CCR but that hut CCR was abolished in a ptsH1 crh double mutant. In contrast, theptsH1 mutation completely relieved hut CCR in cells grown in Luria-Bertani medium. The ptsH1 crh double mutant exhibited several growth defects in glucose minimal medium, including reduced rates of growth and growth inhibition by high levels of glycerol or histidine. CCR is partially relieved in B. subtilis mutants which synthesize low levels of active glutamine synthetase (glnA). In addition, these glnAmutants grow more slowly than wild-type cells in glucose minimal medium. The defects in growth and CCR seen in these mutants are suppressed by mutational inactivation of TnrA, a global nitrogen regulatory protein. The inappropriate expression of TnrA-regulated genes in this class of glnA mutants may deplete intracellular pools of carbon metabolites and thereby result in the reduction of the growth rate and partial relief of CCR.

scholarly journals Regulation of Arabinose and Xylose Metabolism in Escherichia coli

2009 ◽  
Vol 76 (5) ◽  
pp. 1524-1532 ◽  
Author(s):  
Tasha A. Desai ◽  
Christopher V. Rao
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Catabolite Repression ◽  
Carbon Catabolite Repression ◽  
Plant Biomass ◽  
Xylose Metabolism ◽  
Sugar Utilization ◽  
E Coli ◽  
Metabolic Genes ◽  
Pentose Sugars

ABSTRACT Bacteria such as Escherichia coli will often consume one sugar at a time when fed multiple sugars, in a process known as carbon catabolite repression. The classic example involves glucose and lactose, where E. coli will first consume glucose, and only when it has consumed all of the glucose will it begin to consume lactose. In addition to that of lactose, glucose also represses the consumption of many other sugars, including arabinose and xylose. In this work, we characterized a second hierarchy in E. coli, that between arabinose and xylose. We show that, when grown in a mixture of the two pentoses, E. coli will consume arabinose before it consumes xylose. Consistent with a mechanism involving catabolite repression, the expression of the xylose metabolic genes is repressed in the presence of arabinose. We found that this repression is AraC dependent and involves a mechanism where arabinose-bound AraC binds to the xylose promoters and represses gene expression. Collectively, these results demonstrate that sugar utilization in E. coli involves multiple layers of regulation, where cells will consume first glucose, then arabinose, and finally xylose. These results may be pertinent in the metabolic engineering of E. coli strains capable of producing chemical and biofuels from mixtures of hexose and pentose sugars derived from plant biomass.

scholarly journals Bacillus subtilis Mutant LicT Antiterminators Exhibiting Enzyme I- and HPr-Independent Antitermination Affect Catabolite Repression of the bglPH Operon

2002 ◽  
Vol 184 (17) ◽  
pp. 4819-4828 ◽  
Author(s):  
Cordula Lindner ◽  
Michael Hecker ◽  
Dominique Le Coq ◽  
Josef Deutscher
Keyword(s):  
Amino Acids ◽  
Bacillus Subtilis ◽  
Catabolite Repression ◽  
Carbon Catabolite Repression ◽  
Phosphotransferase System ◽  
Terminal Domain ◽  
Target Sites ◽  
Enzyme I ◽  
In Cells

ABSTRACT The Bacillus subtilis antiterminator LicT regulates the expression of bglPH and bglS, which encode the enzymes for the metabolism of aryl-β-glucosides and the β-glucanase BglS. The N-terminal domain of LicT (first 55 amino acids) prevents the formation of ρ-independent terminators on the respective transcripts by binding to target sites overlapping these terminators. Proteins of the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) regulate the antitermination activity of LicT by phosphorylating histidines in its two PTS regulation domains (PRDs). Phosphorylation at His-100 in PRD-1 requires the PTS proteins enzyme I and HPr and the phosphorylated permease BglP and inactivates LicT. During transport and phosphorylation of aryl-β-glucosides, BglP is dephosphorylated, which renders LicT active and thus leads to bglPH and bglS induction. In contrast, phosphorylation at His-207 and/or His-269 in PRD-2, which requires only enzyme I and HPr, is absolutely necessary for LicT activity and bglPH and bglS expression. We isolated spontaneous licT mutants expressing bglPH even when enzyme I and HPr were absent (as indicated by the designation “Pia” [PTS-independent antitermination]). Introduced in a ptsHI + strain, two classes of licT(Pia) mutations could be distinguished. Mutants synthesizing LicT(Pia) antiterminators altered in PRD-2 still required induction by aryl-β-glucosides, whereas mutations affecting PRD-1 caused constitutive bglPH expression. One of the two carbon catabolite repression (CCR) mechanisms operative for bglPH requires the ρ-independent terminator and is probably prevented when LicT is activated by P∼His-HPr-dependent phosphorylation in PRD-2 (where the prefix “P∼” stands for “phospho”). During CCR, the small amount of P∼His-HPr present in cells growing on repressing PTS sugars probably leads to insufficient phosphorylation at PRD-2 of LicT and therefore to reduced bglPH expression. In agreement with this concept, mutants synthesizing a P∼His-HPr-independent LicT(Pia) had lost LicT-modulated CCR.

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