scholarly journals Metabolic Engineering of Corynebacterium glutamicum for Production of UDP-N-Acetylglucosamine

2021 ◽  
Vol 9 ◽  
Author(s):  
Rahul Gauttam ◽  
Christian K. Desiderato ◽  
Dušica Radoš ◽  
Hannes Link ◽  
Gerd M. Seibold ◽  
...  
Keyword(s):  
Corynebacterium Glutamicum ◽  
Growth Phase ◽  
Exponential Growth ◽  
Amino Sugar ◽  
Exponential Growth Phase ◽  
Uridine Diphosphate ◽  
Promising Alternative ◽  
Therapeutic Benefits ◽  
Nucleotide Sugars

Uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) is an acetylated amino sugar nucleotide that naturally serves as precursor in bacterial cell wall synthesis and is involved in prokaryotic and eukaryotic glycosylation reactions. UDP-GlcNAc finds application in various fields including the production of oligosaccharides and glycoproteins with therapeutic benefits. At present, nucleotide sugars are produced either chemically or in vitro by enzyme cascades. However, chemical synthesis is complex and non-economical, and in vitro synthesis requires costly substrates and often purified enzymes. A promising alternative is the microbial production of nucleotide sugars from cheap substrates. In this study, we aimed to engineer the non-pathogenic, Gram-positive soil bacterium Corynebacterium glutamicum as a host for UDP-GlcNAc production. The native glmS, glmU, and glmM genes and glmM of Escherichia coli, encoding the enzymes for UDP-GlcNAc synthesis from fructose-6-phosphate, were over-expressed in different combinations and from different plasmids in C. glutamicum GRS43, which lacks the glucosamine-6-phosphate deaminase gene (nagB) for glucosamine degradation. Over-expression of glmS, glmU and glmM, encoding glucosamine-6-phosphate synthase, the bifunctional glucosamine-1-phosphate acetyltransferase/N-acetyl glucosamine-1-phosphate uridyltransferase and phosphoglucosamine mutase, respectively, was confirmed using activity assays or immunoblot analysis. While the reference strain C. glutamicum GlcNCg1 with an empty plasmid in the exponential growth phase contained intracellularly only about 0.25 mM UDP-GlcNAc, the best engineered strain GlcNCg4 accumulated about 14 mM UDP-GlcNAc. The extracellular UDP-GlcNAc concentrations in the exponential growth phase did not exceed 2 mg/L. In the stationary phase, about 60 mg UDP-GlcNAc/L was observed extracellularly with strain GlcNCg4, indicating the potential of C. glutamicum to produce and to release the activated sugar into the culture medium. To our knowledge, the observed UDP-GlcNAc levels are the highest obtained with microbial hosts, emphasizing the potential of C. glutamicum as a suitable platform for activated sugar production.

scholarly journals Global gene expression analysis of Streptococcus agalactiae at exponential growth phase

2020 ◽  
Author(s):  
Inês Silvestre ◽  
Vítor Borges ◽  
Sílvia Duarte ◽  
Alexandra Nunes ◽  
Rita Sobral ◽  
...  
Keyword(s):  
Gene Expression ◽  
Growth Phase ◽  
Exponential Growth ◽  
Streptococcus Agalactiae ◽  
Molecular Mechanisms ◽  
Reference Strain ◽  
Global Gene Expression ◽  
Exponential Growth Phase ◽  
Expression Levels

AbstractStreptococcus agalactiae is a leading cause of neonatal infections and an increasing cause of infections in adults with underlying diseases. One of the first S. agalactiae isolates to be subjected to whole genome sequencing was NEM316, a strain responsible for a fatal case of septicemia that has been widely used as reference strain for in vitro assays. Whole transcriptome analyses may provide an essential contribute to the understanding of the molecular mechanisms responsible for bacteria adaptation and pathogenicity, still, so far, very few studies were dedicated to the analysis of global gene expression of S. agalactiae. Here, we applied RNA-sequencing to perform a comparative overview of the global gene expression levels of the S. agalactiae reference strain NEM316 at the exponential growth phase. Genes were ranked by expression level and grouped by functional category and 46% of the top-100 expressed genes encode proteins involved in “Translation, ribosomal structure and biogenesis”. Among the group of highly expressed genes were also represented genes with no assigned functional category. Although this result warrants further investigation, most of them might be implicated in stress response. As very little is known about the molecular mechanisms behind the release of DNase’s in vitro and in vivo, we also performed preliminary assays to understand whether direct DNA exposure affects the gene expression of strain NEM316 at the exponential growth phase. No differentially expressed genes were detected, which indicates that follow-up studies are needed to disclose the complex molecular pathways (and stimuli) triggering the release of DNase’s. In general, we provide data on the global expression levels of NEM316 at exponential growth phase that may contribute to better understand S. agalactiae adaptation and virulence.

Activation of the expression of the microcin C51 operon upon glucose starvation of cells at the exponential growth phase

2005 ◽  
Vol 41 (1) ◽  
pp. 40-43
Author(s):  
A. M. Veselovskii ◽  
A. Z. Metlitskaya ◽  
V. A. Lipasova ◽  
I. A. Bass ◽  
I. A. Khmel
Keyword(s):  
Growth Phase ◽  
Exponential Growth ◽  
Exponential Growth Phase ◽  
Glucose Starvation

scholarly journals Differences in power-law growth over time and indicators of COVID-19 pandemic progression worldwide

2020 ◽  
Author(s):  
Jack Merrin
Keyword(s):  
Error Analysis ◽  
Real Time ◽  
Power Law ◽  
Growth Phase ◽  
Exponential Growth ◽  
Spreading Rate ◽  
Exponential Growth Phase ◽  
Power Law Exponent ◽  
Disease Spreading ◽  
Over Time

1AbstractAn automated statistical and error analysis of 45 countries or regions with more than 1000 cases of COVID-19 as of March 28, 2020, has been performed. This study reveals differences in the rate of disease spreading rate over time in different countries. This survey observes that most countries undergo a beginning exponential growth phase, which transitions into a power-law phase, as recently suggested by Ziff and Ziff. Tracking indicators of growth, such as the power-law exponent, are a good indication of the relative danger different countries are in and show when social measures are effective towards slowing the spread. The data compiled here are usefully synthesizing a global picture, identifying country to country variation in spreading, and identifying countries most at risk. This analysis may factor into how best to track the effectiveness of social distancing policies and quarantines in real-time as data is updated each day.

scholarly journals Biosynthesis and turnover of outer-membrane proteins in Escherichia coli ML308-225

1979 ◽  
Vol 182 (2) ◽  
pp. 407-412 ◽  
Author(s):  
R J Allen ◽  
G K Scott
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Outer Membrane ◽  
Bacterial Growth ◽  
Growth Phase ◽  
Exponential Growth ◽  
Outer Membrane Proteins ◽  
Exponential Growth Phase ◽  
Outer Membranes ◽  
Dilution Experiments

Isolated outer membranes and outer-membrane extracts from Escherichia coli ML308-225 in the early-exponential growth phase contain more protein than do corresponding preparations from late-exponential- or stationary-phase bacteria. Isotope-dilution experiments show that this is due to a loss of protein from the membrane during the exponential growth phase. Inhibition of bacterial growth and protein synthesis stabilizes the outer-membrane-protein concentration. Protein synthesis in the absence of bacterial growth results in higher concentrations of protein in the outer membrane.

Exponential growth phase ofPseudomonas methanolica batch cultures

1973 ◽  
Vol 13 (6) ◽  
pp. 523-528 ◽  
Author(s):  
E. M. Shulgovskaya ◽  
I. I. Ivanova ◽  
G. G. Sotnicov
Keyword(s):  
Growth Phase ◽  
Exponential Growth ◽  
Exponential Growth Phase ◽  
Batch Cultures

scholarly journals The Putrescine Importer PuuP of Escherichia coli K-12

2009 ◽  
Vol 191 (8) ◽  
pp. 2776-2782 ◽  
Author(s):  
Shin Kurihara ◽  
Yuichi Tsuboi ◽  
Shinpei Oda ◽  
Hyeon Guk Kim ◽  
Hidehiko Kumagai ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Growth Phase ◽  
Exponential Growth ◽  
Minimal Medium ◽  
Exponential Growth Phase ◽  
E Coli ◽  
Genes Encoding ◽  
K 12 ◽  
Utilization Pathway

ABSTRACT The Puu pathway is a putrescine utilization pathway involving gamma-glutamyl intermediates. The genes encoding the enzymes of the Puu pathway form a gene cluster, the puu gene cluster, and puuP is one of the genes in this cluster. In Escherichia coli, three putrescine importers, PotFGHI, PotABCD, and PotE, were discovered in the 1990s and have been studied; however, PuuP had not been discovered previously. This paper shows that PuuP is a novel putrescine importer whose kinetic parameters are equivalent to those of the polyamine importers discovered previously. A puuP + strain absorbed up to 5 mM putrescine from the medium, but a ΔpuuP strain did not. E. coli strain MA261 has been used in previous studies of polyamine transporters, but PuuP had not been identified previously. It was revealed that the puuP gene of MA261 was inactivated by a point mutation. When E. coli was grown on minimal medium supplemented with putrescine as the sole carbon or nitrogen source, only PuuP among the polyamine importers was required. puuP was expressed strongly when putrescine was added to the medium or when the puuR gene, which encodes a putative repressor, was deleted. When E. coli was grown in M9-tryptone medium, PuuP was expressed mainly in the exponential growth phase, and PotFGHI was expressed independently of the growth phase.

scholarly journals Functional elucidation of the non-coding RNAs of Kluyveromyces marxianus in the exponential growth phase

BMC Genomics ◽  
2016 ◽  
Vol 17 (1) ◽  
Author(s):  
Yoo-Bok Cho ◽  
Eun Ju Lee ◽  
Suhyung Cho ◽  
Tae Yong Kim ◽  
Jin Hwan Park ◽  
...  
Keyword(s):  
Growth Phase ◽  
Exponential Growth ◽  
Kluyveromyces Marxianus ◽  
Exponential Growth Phase ◽  
Non Coding Rnas

Soy Peptides Enhance Heterologous Membrane Protein Productivity during the Exponential Growth Phase ofSaccharomyces cerevisiae

2012 ◽  
Vol 76 (3) ◽  
pp. 628-631 ◽  
Author(s):  
Keisuke ITO ◽  
Aya HIKIDA ◽  
Sayuri KITAGAWA ◽  
Takumi MISAKA ◽  
Keiko ABE ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Growth Phase ◽  
Exponential Growth ◽  
Exponential Growth Phase ◽  
Soy Peptides ◽  
Protein Productivity

Giardia lamblia: axenic growth in autoclaved and filtered Diamond's TYI-S-33 medium

1982 ◽  
Vol 60 (7) ◽  
pp. 1673-1675 ◽  
Author(s):  
M. Belosevic ◽  
G. M. Faubert ◽  
N. A. Croll ◽  
J. D. MacLean
Keyword(s):  
Growth Phase ◽  
Exponential Growth ◽  
Giardia Lamblia ◽  
Culture Medium ◽  
Exponential Growth Phase ◽  
Growth Studies ◽  
Generation Times ◽  
The Mean ◽  
Axenic Growth

The trophozoites of Giardia lamblia were gradually adapted to grow in both autoclaved and filtered Diamond's TYI-S-33 culture medium. Comparative growth studies indicated that the growth of organisms was significantly higher in filtered TYI-S-33 medium. In both types of media the exponential growth phase occurred between 48 and 96 h postinoculation. The mean number of trophozoites at 96 h was 1.94 × 105 and 4.82 × 105 cells/mL for autoclaved and filtered media, respectively. The generation times for the exponential growth phase were 9.66 h. for autoclaved and 7.69 h for filtered medium. The percentage of dead trophozoites was similar in both media and was 14% for the first 8 days postinoculation.

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