scholarly journals Mouse Intestine Selects Nonmotile flhDC Mutants of Escherichia coli MG1655 with Increased Colonizing Ability and Better Utilization of Carbon Sources

2005 ◽  
Vol 73 (12) ◽  
pp. 8039-8049 ◽  
Author(s):  
Mary P. Leatham ◽  
Sarah J. Stevenson ◽  
Eric J. Gauger ◽  
Karen A. Krogfelt ◽  
Jeremy J. Lins ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Carbon Source ◽  
Sole Carbon Source ◽  
Carbon Sources ◽  
Wild Type ◽  
Flagellar Biosynthesis ◽  
Commensal Strain ◽  
Mouse Intestine ◽  
Colonizing Ability ◽  
Better Than

ABSTRACT d-Gluconate which is primarily catabolized via the Entner-Doudoroff (ED) pathway, has been implicated as being important for colonization of the streptomycin-treated mouse large intestine by Escherichia coli MG1655, a human commensal strain. In the present study, we report that an MG1655 Δedd mutant defective in the ED pathway grows poorly not only on gluconate as a sole carbon source but on a number of other sugars previously implicated as being important for colonization, including l-fucose, d-gluconate, d-glucuronate, N-acetyl-d-glucosamine, d-mannose, and d-ribose. Furthermore, we show that the mouse intestine selects mutants of MG1655 Δedd and wild-type MG1655 that have improved mouse intestine-colonizing ability and grow 15 to 30% faster on the aforementioned sugars. The mutants of MG1655 Δedd and wild-type MG1655 selected by the intestine are shown to be nonmotile and to have deletions in the flhDC operon, which encodes the master regulator of flagellar biosynthesis. Finally, we show that ΔflhDC mutants of wild-type MG1655 and MG1655 Δedd constructed in the laboratory act identically to those selected by the intestine; i.e., they grow better than their respective parents on sugars as sole carbon sources and are better colonizers of the mouse intestine.

scholarly journals Role of Motility and the flhDC Operon in Escherichia coli MG1655 Colonization of the Mouse Intestine

2007 ◽  
Vol 75 (7) ◽  
pp. 3315-3324 ◽  
Author(s):  
Eric J. Gauger ◽  
Mary P. Leatham ◽  
Regino Mercado-Lubo ◽  
David C. Laux ◽  
Tyrrell Conway ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Regulatory Region ◽  
Flagellar Motor ◽  
Wild Type ◽  
E Coli ◽  
Mouse Intestine ◽  
Flagellum Biosynthesis ◽  
Colonizing Ability

ABSTRACT Previously, we reported that the mouse intestine selected mutants of Escherichia coli MG1655 that have improved colonizing ability (M. P. Leatham et al., Infect. Immun. 73:8039-8049, 2005). These mutants grew 10 to 20% faster than their parent in mouse cecal mucus in vitro and 15 to 30% faster on several sugars found in the mouse intestine. The mutants were nonmotile and had deletions of various lengths beginning immediately downstream of an IS1 element located within the regulatory region of the flhDC operon, which encodes the master regulator of flagellum biosynthesis, FlhD4C2. Here we show that during intestinal colonization by wild-type E. coli strain MG1655, 45 to 50% of the cells became nonmotile by day 3 after feeding of the strain to mice and between 80 and 90% of the cells were nonmotile by day 15 after feeding. Ten nonmotile mutants isolated from mice were sequenced, and all were found to have flhDC deletions of various lengths. Despite this strong selection, 10 to 20% of the E. coli MG1655 cells remained motile over a 15-day period, suggesting that there is an as-yet-undefined intestinal niche in which motility is an advantage. The deletions appear to be selected in the intestine for two reasons. First, genes unrelated to motility that are normally either directly or indirectly repressed by FlhD4C2 but can contribute to maximum colonizing ability are released from repression. Second, energy normally used to synthesize flagella and turn the flagellar motor is redirected to growth.

scholarly journals Genetically Modified Strains of Ralstonia eutropha H16 with β-Ketothiolase Gene Deletions for Production of Copolyesters with Defined 3-Hydroxyvaleric Acid Contents

2012 ◽  
Vol 78 (15) ◽  
pp. 5375-5383 ◽  
Author(s):  
Nicole Lindenkamp ◽  
Elena Volodina ◽  
Alexander Steinbüchel
Keyword(s):  
Fatty Acids ◽  
Carbon Source ◽  
Sole Carbon Source ◽  
Ralstonia Eutropha ◽  
Carbon Sources ◽  
Production Capacity ◽  
Wild Type ◽  
Content Type ◽  
Storage Behavior ◽  
Copolymer Poly

ABSTRACTβ-Ketothiolases catalyze the first step of poly(3-hydroxybutyrate) [poly(3HB)] biosynthesis in bacteria by condensation of two acetyl coenzyme A (acetyl-CoA) molecules to acetoacetyl-CoA and also take part in the degradation of fatty acids. During growth on propionate or valerate,Ralstonia eutrophaH16 produces the copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [poly(3HB-co-3HV)]. InR. eutropha, 15 β-ketothiolase homologues exist. The synthesis of 3-hydroxybutyryl-CoA (3HB-CoA) could be significantly reduced in an 8-fold mutant (Lindenkamp et al., Appl. Environ. Microbiol. 76:5373–5382, 2010). In this study, a 9-fold mutant deficient in nine β-ketothiolase gene homologues (phaA,bktB, H16_A1713, H16_B1771, H16_A1528, H16_B0381, H16_B1369, H16_A0170, andpcaF) was generated. In order to examine the polyhydroxyalkanoate production capacity when short- or long-chain and even- or odd-chain-length fatty acids were provided as carbon sources, the growth and storage behavior of several mutants from the previous study and the newly generated 9-fold mutant were analyzed. Propionate, valerate, octanoate, undecanoic acid, or oleate was chosen as the sole carbon source. On octanoate, no significant differences in growth or storage behavior were observed between wild-typeR. eutrophaand the mutants. In contrast, during the growth on oleate of a multiple mutant lackingphaA,bktB, and H16_A0170, diminished poly(3HB) accumulation occurred. Surprisingly, the amount of accumulated poly(3HB) in the multiple mutants grown on gluconate differed; it was much lower than that on oleate. The β-ketothiolase activity toward acetoacetyl-CoA in H16ΔphaAand all the multiple mutants remained 10-fold lower than the activity of the wild type, regardless of which carbon source, oleate or gluconate, was employed. During growth on valerate as a sole carbon source, the 9-fold mutant accumulated almost a poly(3-hydroxyvalerate) [poly(3HV)] homopolyester with 99 mol% 3HV constituents.

scholarly journals l-Fucose Stimulates Utilization of d-Ribose by Escherichia coli MG1655 ΔfucAO and E. coli Nissle 1917 ΔfucAO Mutants in the Mouse Intestine and in M9 Minimal Medium

2007 ◽  
Vol 75 (11) ◽  
pp. 5465-5475 ◽  
Author(s):  
Steven M. Autieri ◽  
Jeremy J. Lins ◽  
Mary P. Leatham ◽  
David C. Laux ◽  
Tyrrell Conway ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Minimal Medium ◽  
Wild Type ◽  
E Coli ◽  
Commensal Strain ◽  
Mouse Intestine ◽  
Level 2 ◽  
Growth Experiments

ABSTRACT Escherichia coli MG1655 uses several sugars for growth in the mouse intestine. To determine the roles of l-fucose and d-ribose, an E. coli MG1655 ΔfucAO mutant and an E. coli MG1655 ΔrbsK mutant were fed separately to mice along with wild-type E. coli MG1655. The E. coli MG1655 ΔfucAO mutant colonized the intestine at a level 2 orders of magnitude lower than that of the wild type, but the E. coli MG1655 ΔrbsK mutant and the wild type colonized at nearly identical levels. Surprisingly, an E. coli MG1655 ΔfucAO ΔrbsK mutant was eliminated from the intestine by either wild-type E. coli MG1655 or E. coli MG1655 ΔfucAO, suggesting that the ΔfucAO mutant switches to ribose in vivo. Indeed, in vitro growth experiments showed that l-fucose stimulated utilization of d-ribose by the E. coli MG1655 ΔfucAO mutant but not by an E. coli MG1655 ΔfucK mutant. Since the ΔfucK mutant cannot convert l-fuculose to l-fuculose-1-phosphate, whereas the ΔfucAO mutant accumulates l-fuculose-1-phosphate, the data suggest that l-fuculose-1-phosphate stimulates growth on ribose both in the intestine and in vitro. An E. coli Nissle 1917 ΔfucAO mutant, derived from a human probiotic commensal strain, acted in a manner identical to that of E. coli MG1655 ΔfucAO in vivo and in vitro. Furthermore, l-fucose at a concentration too low to support growth stimulated the utilization of ribose by the wild-type E. coli strains in vitro. Collectively, the data suggest that l-fuculose-1-phosphate plays a role in the regulation of ribose usage as a carbon source by E. coli MG1655 and E. coli Nissle 1917 in the mouse intestine.

scholarly journals Cinnamic Acid, an Autoinducer of Its Own Biosynthesis, Is Processed via Hca Enzymes in Photorhabdus luminescens

2008 ◽  
Vol 74 (6) ◽  
pp. 1717-1725 ◽  
Author(s):  
Sabina Chalabaev ◽  
Evelyne Turlin ◽  
Sylvie Bay ◽  
Christelle Ganneau ◽  
Emma Brito-Fravallo ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Carbon Source ◽  
Cinnamic Acid ◽  
Aromatic Compounds ◽  
Sole Carbon Source ◽  
Biosynthetic Pathway ◽  
Phenylalanine Ammonia Lyase ◽  
Carbon Sources ◽  
Degradation Pathway ◽  
Photorhabdus Luminescens

ABSTRACT Photorhabdus luminescens, an entomopathogenic bacterium and nematode symbiont, has homologues of the Hca and Mhp enzymes. In Escherichia coli, these enzymes catalyze the degradation of the aromatic compounds 3-phenylpropionate (3PP) and cinnamic acid (CA) and allow the use of 3PP as sole carbon source. P. luminescens is not able to use 3PP and CA as sole carbon sources but can degrade them. Hca dioxygenase is involved in this degradation pathway. P. luminescens synthesizes CA from phenylalanine via a phenylalanine ammonia-lyase (PAL) and degrades it via the not-yet-characterized biosynthetic pathway of 3,5-dihydroxy-4-isopropylstilbene (ST) antibiotic. CA induces its own synthesis by enhancing the expression of the stlA gene that codes for PAL. P. luminescens bacteria release endogenous CA into the medium at the end of exponential growth and then consume it. Hca dioxygenase is involved in the consumption of endogenous CA but is not required for ST production. This suggests that CA is consumed via at least two separate pathways in P. luminescens: the biosynthesis of ST and a pathway involving the Hca and Mhp enzymes.

Development of mutants of Gliocladium virens tolerant to benomyl

1990 ◽  
Vol 36 (7) ◽  
pp. 484-489 ◽  
Author(s):  
G. C. Papavizas ◽  
D. P. Roberts ◽  
K. K. Kim
Keyword(s):  
Carbon Source ◽  
Type Strain ◽  
Wild Type Strain ◽  
Carbon Sources ◽  
Sclerotium Rolfsii ◽  
Wild Type ◽  
Gliocladium Virens ◽  
Rhizosphere Competence ◽  
Filter Paper Cellulase ◽  
Type Strains

Aqueous suspensions of conidia of Gliocladium virens strains Gl-3 and Gl-21 were exposed to both ultraviolet radiation and ethyl methanesulfonate. Two mutants of Gl-3 and three of Gl-21 were selected for tolerance to benomyl at 10 μg∙mL−1, as indicated by growth and conidial germination on benomyl-amended potato dextrose agar. The mutants differed considerably from their respective wild-type strains in appearance, growth habit, sporulation, carbon-source utilization, and enzyme activity profiles. Of 10 carbon sources tested, cellobiose, xylose, and xylan were the best for growth, galactose and glucose were intermediate, and arabinose, ribose, and rhamnose were poor sources of carbon. The wild-type strains and the mutants did not utilize cellulose as the sole carbon source for growth. Two benomyl-tolerant mutants of Gl-3 produced less cellulase (β-1,4-glucosidase, carboxymethylcellulase, filter-paper cellulase) than Gl-3. In contrast, mutants of Gl-21 produced more cellulase than the wild-type strain. Only Gl-3 provided control of blight on snapbean caused by Sclerotium rolfsii. Wild-type strain Gl-21 and all mutants from both strains were ineffective biocontrol agents. Key words: Gliocladium, benomyl tolerance, Sclerotium, rhizosphere competence.

scholarly journals Mutants affecting histidine utilization inAspergillus nidulans

1975 ◽  
Vol 25 (2) ◽  
pp. 119-135 ◽  
Author(s):  
Meryl Polkinghorne ◽  
M. J. Hynes
Keyword(s):  
Carbon Source ◽  
Nitrogen Source ◽  
Sole Carbon Source ◽  
Nitrogen Sources ◽  
Limiting Factor ◽  
Sole Nitrogen Source ◽  
Wild Type ◽  
Exogenous Substrate ◽  
Growth Properties ◽  
Type Strains

SUMMARYWild-type strains ofAspergillus nidulansgrow poorly onL-histidine as a sole nitrogen source. The synthesis of the enzyme histidase (EC. 4.3.1.3) appears to be a limiting factor in the growth of the wild type, as strains carrying the mutantareA102 allele have elevated histidase levels and grow strongly on histidine as a sole nitrogen source.L-Histidine is an extremely weak sole carbon source for all strains.Ammonium repression has an important role in the regulation of histidase synthesis and the relief of ammonium repression is dependent on the availability of a good carbon source. The level of histidase synthesis does not respond to the addition of exogenous substrate.Mutants carrying lesions in thesarA orsarB loci (suppressor ofareA102) have been isolated. The growth properties of these mutants on histidine as a sole nitrogen source correlate with the levels of histidase synthesized. Mutation at thesarA andsarB loci also reduces the utilization of a number of other nitrogen sources. The data suggest that these two genes may code for regulatory products involved in nitrogen catabolism. No histidase structural gene mutants were identified and possible explanations of this are discussed.

scholarly journals Screening of local wild-type Xanthomonas spp. for xanthan biosynthesis using media with different carbon sources

2021 ◽  
Vol 26 (4) ◽  
pp. 2800-2807
Author(s):  
IDA ZAHOVIĆ ◽  
JELENA DODIĆ ◽  
SINIŠA MARKOV ◽  
JOVANA GRAHOVAC ◽  
MILA GRAHOVAC ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Carbon Source ◽  
Carbon Sources ◽  
Wild Type ◽  
Biotechnological Production ◽  
Aerobic Conditions ◽  
Pepper Leaves ◽  
Synthetic Media ◽  
Selection Of

In this study the screening of different Xanthomonas strains, isolated from infected crucifers and pepper leaves, for xanthan biosynthesis on semi-synthetic media containing different carbon sources was performed. The success of xanthan biosynthesis was estimated based on xanthan concentration in media and its molecular weight. Glucose and glycerol were investigated as carbon sources in a quantity of 20.0 g/L. Xanthan biosynthesis by different Xanthomonas isolates on two different cultivation media was carried out in Erlenmeyer flasks under aerobic conditions for 168 h. According to the obtained results selection of the carbon source, producing strain and their combination have a statistically significant effect on xanthan quantity and quality. The results obtained in this study indicate that local wild-type Xanthomonas strains isolated from pepper leaves have a great potential for application in biotechnological production of good-quality xanthan on glycerol-based media.

Mannose utilization in Escherichia coli requires cyclic AMP but not an exogenous inducer

1980 ◽  
Vol 26 (12) ◽  
pp. 1508-1511 ◽  
Author(s):  
Ann D. E. Fraser ◽  
Hiroshi Yamazaki
Keyword(s):  
Escherichia Coli ◽  
Carbon Source ◽  
Cyclic Amp ◽  
Adenylyl Cyclase ◽  
Sole Carbon Source ◽  
Receptor Protein ◽  
Deficient Mutant ◽  
Phosphotransferase System ◽  
Cyclic Amp Receptor Protein ◽  
Cyclic Monophosphate

It has not been clarified whether the utilization of mannose by Escherichia coli requires adenosine 3′,5′-cyclic monophosphate (cyclic AMP). Using an adenylyl cyclase deficient mutant (CA8306B) and a cyclic AMP receptor protein (CRP) deficient mutant (5333B) we have shown that the utilization of mannose is dependent on the cyclic AMP–CRP complex. 2-Deoxyglucose (DG) is a nonmetabolizable glucose analog specific for the phosphotransferase system (PTS) which transports mannose (termed here PTSM). Growth of CA8306B on glycerol is unaffected by addition of the analog, whereas growth of the strain on glycerol plus cyclic AMP ceases im mediately upon addition of DG. These results suggest that the formation of PTSM is dependent on cyclic AMP. In addition, CA8306B grown on glycerol plus cyclic AMP can immediately utilize mannose when transferred to a medium containing mannose as a sole carbon source, whereas the same strain grown on glycerol without cyclic AMP cannot utilize mannose when so transferred. These results suggest that the formation of PTSM does not require an exogenous inducer.

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