Ontology highlight
ABSTRACT:
PROVIDER: PRJNA990930 | ENA |
REPOSITORIES: ENA
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Project description:D-lactic acid is a three-carbon organic acid with a chiral structure and can improve the thermostability of polylactic acid. Microorganisms such as the methylotrophic yeast Pichia pastoris, which lack the natural ability to produce or accumulate high amounts of D-lactic acid, have been engineered to produce it in high titers. However, tolerance to D-lactic acid remains a challenge. In this study, we demonstrate that cell flocculation improves tolerance to D-lactic acid and leads to increased D-lactic acid production in Pichia pastoris. By incorporating a flocculation gene from Saccharomyces cerevisiae (ScFLO1) into P. pastoris KM71, we created a strain (KM71-ScFlo1) that demonstrated up to a 1.6-fold improvement in specific growth rate at high D-lactic acid concentrations. Furthermore, integrating a D-lactate dehydrogenase gene from Leuconostoc pseudomesenteroides (LpDLDH) into KM71-ScFlo1 resulted in an engineered strain (KM71-ScFlo1-LpDLDH) that can produce D-lactic acid at a titer of 5.12 0.35 g/L in 48 hours , a 2.6-fold improvement over the control strain lacking ScFLO1 expression. Transcriptomics analysis of this strain provided insights into the mechanism of increased tolerance to D-lactic acid including the upregulations of genes involved in lactate transport and iron metabolism. Overall, our work represents an advancement in the efficient microbial production of D-lactic acid by manipulating yeast flocculation.
2023-04-01 | GSE224837 | GEO
Project description:Enterococcus faecalis, a member of the human gastrointestinal microbiota, is a Gram-positive, opportunistic pathogen associated with hospital-acquired wound, bloodstream, and urinary tract infections. E. faecalis can suppress or evade immune-mediated clearance by macrophages to promote persistent infection, although the exact mechanisms and bacterial factor(s) involved are not well-defined. In this study, we examined E. faecalis factor(s) involved in suppressing macrophage activation, as well the macrophage pathways modulated by E. faecalis to suppress activation. We observed that E. faecalis prevents ERK and p65 phosphorylation and reduces MyD88 expression leading to a reduction in NF-κB activity. We identified E. faecalis lactate dehydrogenase, which is important for lactic acid production by E. faecalis, to be necessary for macrophage suppression and demonstrated that E. faecalis lactate dehydrogenase-mediated immune suppression promotes E. coli survival during polymicrobial wound infection. Taken together, these results suggest that that E. faecalis-derived lactic acid is involved in macrophage subversion and may help to promote the virulence of co-infecting bacteria.
2024-11-01 | GSE188916 | GEO
Project description:The Lactobacillus buchneri CD034 strain, known to improve the ensiling process of green fodder and the quality of the silage itself was transcriptionally analyzed by sequencing of transcriptomes isolated under anaerobic vs. aerobic conditions. L. buchneri CD034 was first cultivated under anaerobic conditions and then shifted to aerobic conditions by aeration with 21% oxygen. Cultivations already showed that oxygen was consumed by L. buchneri CD034 after aeration of the culture while growth of L. buchneri CD034 was still observed. RNA sequencing data revealed that irrespective of the oxygen status of the culture, the most abundantly transcribed genes are required for basic cell functions such as protein biosynthesis, energy metabolism and lactic acid fermentation. Under aerobic conditions, 283 genes were found to be transcriptionally up-regulated while 198 genes were found to be down-regulated (p-value < 0.01). Up-regulated genes i. a. play a role in oxygen consumption via oxidation of pyruvate or lactate (pox, lctO). Additionally, genes encoding proteins required for decomposition of reactive oxygen species (ROS) such as glutathione reductase or NADH peroxidase were also found to be up-regulated. Genes related to pH homeostasis and redox potential balance were found to be down-regulated under aerobic conditions. Overall, genes required for lactic acid fermentation were hardly affected by the growth conditions applied. Genes identified to be differentially transcribed depending on the aeration status of the culture are suggested to specify the favorable performance of the strain in silage formation.
2017-02-10 | GSE67802 | GEO
Project description:Staphylococcus aureus is an important food poisoning bacterium. In food preservation, acidification is a well-known method. Permeant weak organic acids, like lactic and acetic acids, are known to be more effective against bacteria than inorganic strong acids (e.g., HCl). Growth experiments and metabolic and transcriptional analyses were used to determine the responses of a food pathogenic S. aureus strain exposed to lactic acid, acetic acid, and HCl at pH 4.5. Lactic and acetic acid stress induced a slower transcriptional response and large variations in growth patterns compared with the responses induced by HCl. In cultures acidified with lactic acid, the pH of the medium gradually increased to 7.5 during growth, while no such increase was observed for bacteria exposed to acetic acid or HCl. Staphylococcus aureus increased the pH in the medium mainly through accumulation of ammonium and the removal of acid groups, resulting in increased production of diacetyl (2,3-butanedione) and pyrazines. The results showed flexible and versatile responses of S. aureus to different types of acid stress. As measured by growth inhibition, permeant organic acid stress introduced severe stress compared with the stress caused by HCl. Cells exposed to lactic acid showed specific mechanisms of action in addition to sharing many of the mechanisms induced by HCl stress. Data is also available from http://bugs.sgul.ac.uk/E-BUGS-87
2011-04-15 | E-BUGS-87 | biostudies-arrayexpress
Project description:The present study aims to explore chemostat-based transcriptome analysis of mixed cultures by investigating interactions between the yeast S. cerevisiae and the lactic acid bacterium L. bulgaricus . S. cerevisiae and L. bulgaricus are both frequently encountered in kefir, a fermented dairy product. In the context of this study, this binary culture serves as a model for the many traditional food and beverage fermentation processes in which yeasts and lactic acid bacteria occur together. The design of the cultivation conditions was based on the observation that L. bulgaricus, but not S. cerevisiae, can use lactose as a carbon source for growth and that S. cerevisiae, but not L. bulgaricus, can grow on galactose that is released upon hydrolysis of lactose by the bacterial β-galactosidase. Mixed populations of yeasts and lactic acid bacteria occur in many dairy, food and beverage fermentations, but knowledge about their interactions is incomplete. In the present study, interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus, two microorganisms that co-occur in kefir fermentations, were studied during anaerobic growth on lactose. By combining physiological and transcriptome analysis of the two strains in the co-cultures, five mechanisms of interaction were identified. 1. L. bulgaricus hydrolyses lactose, which cannot be metabolized by S. cerevisiae, to galactose and glucose. Subsequently, galactose, which cannot be metabolized by L. bulgaricus, is excreted and provides a carbon source for yeast. 2. In pure cultures, L. bulgaricus only grows at increased CO2 concentrations. In anaerobic mixed cultures, the yeast provides this CO2 via alcoholic fermentation. 3. Analysis of amino acid consumption from the defined medium indicated that S. cerevisiae supplied alanine to the bacteria. 4. A mild but significant low-iron response in the yeast transcriptome, identified by DNA microarray analysis, was consistent with the chelation of iron by the lactate produced by L. bulgaricus. 5. Transcriptome analysis of L. bulgaricus in mixed cultures showed an overrepresentation of transcripts involved in lipids metabolism suggesting either a competition of the two microorganisms for fatty acids, or a response to the ethanol produced by S. cerevisiae.
2013-04-01 | GSE45623 | GEO
Project description:The present study aims to explore chemostat-based transcriptome analysis of mixed cultures by investigating interactions between the yeast S. cerevisiae and the lactic acid bacterium Lb. bulgaricus . S. cerevisiae and Lb. bulgaricus are both frequently encountered in kefir, a fermented dairy product (25). In the context of this study, this binary culture serves as a model for the many traditional food and beverage fermentation processes in which yeasts and lactic acid bacteria occur together (19,26-30). The design of the cultivation conditions was based on the observation that Lb. bulgaricus, but not S. cerevisiae, can use lactose as a carbon source for growth and that S. cerevisiae, but not Lb. bulgaricus, can grow on galactose that is released upon hydrolysis of lactose by the bacterial M-NM-2-galactosidase. Mixed populations of yeasts and lactic acid bacteria occur in many dairy, food and beverage fermentations, but knowledge about their interactions is incomplete. In the present study, interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus, two microorganisms that co-occur in kefir fermentations, were studied during anaerobic growth on lactose. By combining physiological and transcriptome analysis of the two strains in the co-cultures, five mechanisms of interaction were identified. 1. Lb. bulgaricus hydrolyses lactose, which cannot be metabolized by S. cerevisiae, to galactose and glucose. Subsequently, galactose, which cannot be metabolized by Lb. bulgaricus, is excreted and provides a carbon source for yeast. 2. In pure cultures, Lb. bulgaricus only grows at increased CO2 concentrations. In anaerobic mixed cultures, the yeast provides this CO2 via alcoholic fermentation. 3. Analysis of amino acid consumption from the defined medium indicated that S. cerevisiae supplied alanine to the bacteria. 4. A mild but significant low-iron response in the yeast transcriptome, identified by DNA microarray analysis, was consistent with the chelation of iron by the lactate produced by Lb. bulgaricus. 5. Transcriptome analysis of Lb. bulgaricus in mixed cultures showed an overrepresentation of transcripts involved in lipids metabolism suggesting either a competition of the two microorganisms for fatty acids, or a response to the ethanol produced by S. cerevisiae. To our knowledge, this is the first transcriptome study of a cross-kingdom binary mixed culture that analyses responses of both microorganisms. This study demonstrates that chemostat-based transcriptome analysis is a powerful tool to investigated microbial interaction in mixed populations. To investigate the impact of of co-cultivation with Lb. bulgaricus on S. cerevisiae, a DNA microarray-based transcriptome analysis of S. cerevisiae's response was performed on anaerobic, lactose-limited chemostat cultures grown in the presence and absence of L. bulgaricus.
2013-08-22 | E-GEOD-45776 | biostudies-arrayexpress