Public-good driven release of heterogeneous resources leads to genotypic diversification of an isogenic yeast population in melibiose.

Adaptive diversification of an isogenic population, and its molecular basis has been a subject of a number of studies in the last few years. Microbial populations offer a relatively convenient model system to study this question. In this context, an isogenic population of bacteria (E. coli, B. subtilis, and Pseudomonas) has been shown to lead to genetic diversification in the population, when propagated for a number of generations. This diversification is known to occur when the individuals in the population have access to two or more resources/environments, which are separated either temporally or spatially. Here, we report adaptive diversification in an isogenic population of yeast, S. cerevisiae, when propagated in an environment containing melibiose as the carbon source. The diversification is driven due to a public good, enzyme α-galactosidase, leading to hydrolysis of melibiose into two distinct resources, glucose and galactose. The diversification is driven by a mutations at a single locus, in the GAL3 gene in the GAL/MEL regulon in the yeast.

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Viruses–exploiters or dependants of the host?

Parasitology ◽

10.1017/s0031182000054251 ◽

1982 ◽

Vol 85 (1) ◽

pp. 189-216 ◽

Cited By ~ 1

Author(s):

Alison A. Newton

Keyword(s):

Host Cell ◽

Virus Replication ◽

Cell Biology ◽

Molecular Basis ◽

Molecular Mechanisms ◽

Model System ◽

Great Emphasis ◽

Genetic Organization ◽

Biological Aspects ◽

Convenient Model

Viruses are frequently referred to as the supreme parasites and yet it is now more than 20 years since any paper on this topic was published inParasitology. This deficiency probably reflects the great emphasis placed during the last two decades on those aspects of virology christened by Sir Christopher Andrewes ‘dream virology’ (Andrewes, 1973), namely the molecular and genetic properties of viruses, in contrast to the more clinical and biological aspects of ‘steam’ virology. Many modern virologists select a virus as a convenient model system with which to investigate such things as genetic organization or control of transcription, with little regard for the interaction with the host cell that supports its replication. Paradoxically, it is this very emphasis on the detailed molecular mechanisms of virus replication that has now put us in a better position to understand the relationships between these highly specialized parasites and their host systems than for any other type of parasite. Recent advances in cell biology coupled with an understanding of the molecular basis of viral replicative mechanisms mean that new insight is possible into the interactions of a virus with its host. For example, we are just beginning to appreciate why a virus should infect one individual and not another, or why it should multiply only in certain tissues at certain stages of development of a multicellular organism. Indeed, study of such tropisms may frequently tell us as much about the host cell as about the virus.

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Expanding the nematode model system: The molecular basis of inflammation and infection recovery in C. elegans

Virulence ◽

10.1080/21505594.2016.1239011 ◽

2016 ◽

Vol 8 (3) ◽

pp. 244-245 ◽

Cited By ~ 1

Author(s):

Gabriel Hendricks ◽

Eleftherios Mylonakis

Keyword(s):

Molecular Basis ◽

Model System ◽

C Elegans

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A Comparison of Hand Washing Techniques To Remove Escherichia coli and Caliciviruses under Natural or Artificial Fingernails

Journal of Food Protection ◽

10.4315/0362-028x-66.12.2296 ◽

2003 ◽

Vol 66 (12) ◽

pp. 2296-2301 ◽

Cited By ~ 45

Author(s):

CHIA-MIN LIN ◽

FONE-MAO WU ◽

HOI-KYUNG KIM ◽

MICHAEL P. DOYLE ◽

BARRY S. MICHAELS ◽

...

Keyword(s):

Escherichia Coli ◽

Tap Water ◽

Hand Washing ◽

Microbial Populations ◽

Liquid Soap ◽

E Coli ◽

Hand Sanitizer ◽

Before And After ◽

Escherichia Coli Jm109 ◽

Viral Indicators

Compared with other parts of the hand, the area beneath fingernails harbors the most microorganisms and is most difficult to clean. Artificial fingernails, which are usually long and polished, reportedly harbor higher microbial populations than natural nails. Hence, the efficacy of different hand washing methods for removing microbes from natural and artificial fingernails was evaluated. Strains of nonpathogenic Escherichia coli JM109 and feline calicivirus (FCV) strain F9 were used as bacterial and viral indicators, respectively. Volunteers with artificial or natural nails were artificially contaminated with ground beef containing E. coli JM109 or artificial feces containing FCV. Volunteers washed their hands with tap water, regular liquid soap, antibacterial liquid soap, alcohol-based hand sanitizer gel, regular liquid soap followed by alcohol gel, or regular liquid soap plus a nailbrush. The greatest reduction of inoculated microbial populations was obtained by washing with liquid soap plus a nailbrush, and the least reduction was obtained by rubbing hands with alcohol gel. Lower but not significantly different (P > 0.05) reductions of E. coli and FCV counts were obtained from beneath artificial than from natural fingernails. However, significantly (P ≤ 0.05) higher E. coli and FCV counts were recovered from hands with artificial nails than from natural nails before and after hand washing. In addition, microbial cell numbers were correlated with fingernail length, with greater numbers beneath fingernails with longer nails. These results indicate that best practices for fingernail sanitation of food handlers are to maintain short fingernails and scrub fingernails with soap and a nailbrush when washing hands.

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Reduction of Microorganisms on Citrus Fruit Surfaces during Packinghouse Processing

Journal of Food Protection ◽

10.4315/0362-028x-61.7.903 ◽

1998 ◽

Vol 61 (7) ◽

pp. 903-906 ◽

Cited By ~ 39

Author(s):

STEVEN PAO ◽

G. ELDON BROWN

Keyword(s):

Test Organism ◽

Citrus Fruit ◽

Microbial Populations ◽

Most Probable Number ◽

Probable Number ◽

E Coli ◽

Plate Counts ◽

High Level ◽

Inoculation Study ◽

Fruit Surface

Citrus fruit surface microbial populations were evaluated following various packingline processes of seven Florida commercial packinghouses. At each packinghouse, six fruits (oranges or tangerines) were collected at each of four sampling points. The sampling was conducted in duplicate; thus, 336 fruit were evaluated during this survey. Average aerobic plate counts and yeast and mold counts on fruit surfaces before washing were about 4.0 log CFU/cm2 and 3.3 log CFU/cm2, respectively, and were reduced to 2.1 log CFU/cm2 and 1.3 log CFU/cm2, respectively, by packinghouse processing. Waxing alone reduced the average fruit surface aerobic plate counts and coliform counts from 3.7 log CFU/cm2 and 35.2 most probable number (MPN)/cm2, respectively, to 2.6 log CFU/cm2 and 1.4 MPN/cm2. No Escherichia coli was recovered from fruit at the end of packinghouse processing, and no salmonellae were found on fruit during the entire processing. In an inoculation study to test the effect of packinghouse processes, test organism E. coli was applied to fruit to achieve a high level (4.8 log CFU/cm2) of contamination. The average E. coli count was reduced about 2.4 log cycles by washing and rinsing with potable water (40 psi, 25 °C) for about 30 s. The combination of washing and waxing significantly reduced the inoculated level of E. coli from 4.8 to 1.4 log CFU/cm2.

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Antimicrobial Activity of Gaseous Allyl Isothiocyanate

Journal of Food Protection ◽

10.4315/0362-028x-60.8.943 ◽

1997 ◽

Vol 60 (8) ◽

pp. 943-947 ◽

Cited By ~ 86

Author(s):

PASCAL J. DELAQUIS ◽

PETER L. SHOLBERG

Keyword(s):

Bacterial Species ◽

Allyl Isothiocyanate ◽

Model System ◽

Penicillium Expansum ◽

Escherichia Coli O157 ◽

Fluorescent Pseudomonad ◽

Bacterial Cells ◽

E Coli ◽

Simple Model System ◽

Germination And Growth

A simple model system was constructed to evaluate the microbistatic and microbicidal properties of gaseous allyl isothiocyanate (AIT) against bacterial cells and fungal conidia deposited on agar surfaces. Salmonella typhimurium, Listeria monocytogenes Scott A, and Escherichia coli O157:H7 were inhibited when exposed to 1,000 μg AIT per liter. Pseudomonas corrugata, a Cytophaga species, and a fluorescent pseudomonad failed to grow in the presence of 500 μg AIT per liter. Germination and growth of Penicillium expansum, Aspergillus flavus, and Botrytis cinerea conidia was inhibited in the presence of 100 μg AIT per liter. Bactericidal and sporicidal activities varied with strain and increased with time of exposure, AIT concentration, and temperature. E. coli O157:H7 was the most resistant bacterial species tested.

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Biosynthesis of 1,3-propanediol from recombinant E. coli by optimization process using pure and crude glycerol as a sole carbon source under two-phase fermentation system

World Journal of Microbiology and Biotechnology ◽

10.1007/s11274-013-1556-1 ◽

2013 ◽

Vol 30 (4) ◽

pp. 1359-1368 ◽

Cited By ~ 5

Author(s):

Rosarin Rujananon ◽

Poonsuk Prasertsan ◽

Amornrat Phongdara

Keyword(s):

Carbon Source ◽

Sole Carbon Source ◽

Crude Glycerol ◽

Optimization Process ◽

Two Phase ◽

Fermentation System ◽

E Coli

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High-resolution crystal structures of Escherichia coli FtsZ bound to GDP and GTP

Acta Crystallographica Section F Structural Biology Communications ◽

10.1107/s2053230x20001132 ◽

2020 ◽

Vol 76 (2) ◽

pp. 94-102 ◽

Cited By ~ 2

Author(s):

Maria A. Schumacher ◽

Tomoo Ohashi ◽

Lauren Corbin ◽

Harold P. Erickson

Keyword(s):

Escherichia Coli ◽

Staphylococcus Aureus ◽

Cell Division ◽

High Resolution ◽

Crystal Structures ◽

Bacterial Cell ◽

Model System ◽

E Coli ◽

Z Ring ◽

Main Model

Bacterial cytokinesis is mediated by the Z-ring, which is formed by the prokaryotic tubulin homolog FtsZ. Recent data indicate that the Z-ring is composed of small patches of FtsZ protofilaments that travel around the bacterial cell by treadmilling. Treadmilling involves a switch from a relaxed (R) state, favored for monomers, to a tense (T) conformation, which is favored upon association into filaments. The R conformation has been observed in numerous monomeric FtsZ crystal structures and the T conformation in Staphylococcus aureus FtsZ crystallized as assembled filaments. However, while Escherichia coli has served as a main model system for the study of the Z-ring and the associated divisome, a structure has not yet been reported for E. coli FtsZ. To address this gap, structures were determined of the E. coli FtsZ mutant FtsZ(L178E) with GDP and GTP bound to 1.35 and 1.40 Å resolution, respectively. The E. coli FtsZ(L178E) structures both crystallized as straight filaments with subunits in the R conformation. These high-resolution structures can be employed to facilitate experimental cell-division studies and their interpretation in E. coli.

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On-site integrated production of cellulases and β-glucosidases by Trichoderma reesei Rut C30 using steam-pretreated sugarcane bagasse

10.1101/461012 ◽

2018 ◽

Cited By ~ 3

Author(s):

Marcella Fernandes de Souza ◽

Elba Pinto da Silva Bon ◽

Ayla Sant’ Ana da Silvab

Keyword(s):

Carbon Source ◽

Lignocellulosic Biomass ◽

Trichoderma Reesei ◽

Sugarcane Bagasse ◽

Enzyme Preparation ◽

Integrated Approach ◽

Aspergillus Awamori ◽

Pretreated Sugarcane Bagasse ◽

Hydrolysis Of ◽

Rut C30

AbstractThe high cost of commercial cellulases still hampers the economic competitiveness of the production of fuels and chemicals from lignocellulosic biomasses. This cost may be decreased by the on-site production of cellulases with the integrated use of the lignocellulosic biomass as carbon source. This integrated approach was evaluated in the present study whereby steam-pretreated sugarcane bagasse (SPSB) was used as carbon source for the production of cellulases by Trichoderma reesei Rut C30 and the produced enzymes were subsequently used for SPSB hydrolysis. An enzyme preparation with a high cellulase activity, of 1.93 FPU/mL, was obtained, and a significant β-glucosidase activity was achieved in buffered media, indicating the importance of pH control during enzyme production. The hydrolysis of SPSB with the laboratory-made mixture resulted in a glucose yield of 80%, which was equivalent to those observed for control experiments using commercial enzymes. Even though the supplementation of this mixture with external β-glucosidase from Aspergillus awamori was found to increase the initial hydrolysis rates, it had no impact on the final hydrolysis yield. It was shown that SPSB is a promising carbon source for the production of cellulases and β-glucosidases by T. reesei Rut C30 and that the enzyme preparation obtained is effective for the hydrolysis of SPSB, supporting the on-site integrated approach to decrease the cost of the enzymatic hydrolysis of lignocellulosic biomass.

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