1
|
Wang Y, Mairinger W, Raj SJ, Yakubu H, Siesel C, Green J, Durry S, Joseph G, Rahman M, Amin N, Hassan MZ, Wicken J, Dourng D, Larbi E, Adomako LAB, Senayah AK, Doe B, Buamah R, Tetteh-Nortey JNN, Kang G, Karthikeyan A, Roy S, Brown J, Muneme B, Sene SO, Tuffuor B, Mugambe RK, Bateganya NL, Surridge T, Ndashe GM, Ndashe K, Ban R, Schrecongost A, Moe CL. Quantitative assessment of exposure to fecal contamination in urban environment across nine cities in low-income and lower-middle-income countries and a city in the United States. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 763:143007. [PMID: 34718001 DOI: 10.1016/j.scitotenv.2020.143007] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 10/08/2020] [Accepted: 10/08/2020] [Indexed: 05/23/2023]
Abstract
BACKGROUND During 2014 to 2019, the SaniPath Exposure Assessment Tool, a standardized set of methods to evaluate risk of exposure to fecal contamination in the urban environment through multiple exposure pathways, was deployed in 45 neighborhoods in ten cities, including Accra and Kumasi, Ghana; Vellore, India; Maputo, Mozambique; Siem Reap, Cambodia; Atlanta, United States; Dhaka, Bangladesh; Lusaka, Zambia; Kampala, Uganda; Dakar, Senegal. OBJECTIVE Assess and compare risk of exposure to fecal contamination via multiple pathways in ten cities. METHODS In total, 4053 environmental samples, 4586 household surveys, 128 community surveys, and 124 school surveys were collected. E. coli concentrations were measured in environmental samples as an indicator of fecal contamination magnitude. Bayesian methods were used to estimate the distributions of fecal contamination concentration and contact frequency. Exposure to fecal contamination was estimated by the Monte Carlo method. The contamination levels of ten environmental compartments, frequency of contact with those compartments for adults and children, and estimated exposure to fecal contamination through any of the surveyed environmental pathways were compared across cities and neighborhoods. RESULTS Distribution of fecal contamination in the environment and human contact behavior varied by city. Universally, food pathways were the most common dominant route of exposure to fecal contamination across cities in low-income and lower-middle-income countries. Risks of fecal exposure via water pathways, such as open drains, flood water, and municipal drinking water, were site-specific and often limited to smaller geographic areas (i.e., neighborhoods) instead of larger areas (i.e., cities). CONCLUSIONS Knowledge of the relative contribution to fecal exposure from multiple pathways, and the environmental contamination level and frequency of contact for those "dominant pathways" could provide guidance for Water, Sanitation, and Hygiene (WASH) programming and investments and enable local governments and municipalities to improve intervention strategies to reduce the risk of exposure to fecal contamination.
Collapse
Affiliation(s)
- Yuke Wang
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA.
| | - Wolfgang Mairinger
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Suraja J Raj
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Habib Yakubu
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Casey Siesel
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Jamie Green
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Sarah Durry
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - George Joseph
- Water Global Practice, The World Bank, Washington, DC, USA
| | - Mahbubur Rahman
- Environmental Interventions Unit, Infectious Disease Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Nuhu Amin
- Environmental Interventions Unit, Infectious Disease Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | | | | | | | - Eugene Larbi
- Training Research and Networking for Development (TREND), Accra, Ghana
| | | | | | - Benjamin Doe
- Training Research and Networking for Development (TREND), Accra, Ghana
| | - Richard Buamah
- Department of Civil Engineering, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | | | - Gagandeep Kang
- Wellcome Research Laboratory, Christian Medical College, Vellore, India
| | - Arun Karthikeyan
- Wellcome Research Laboratory, Christian Medical College, Vellore, India
| | - Sheela Roy
- Wellcome Research Laboratory, Christian Medical College, Vellore, India
| | - Joe Brown
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, USA
| | - Bacelar Muneme
- Water Supply and Mapping, WE Consult, Maputo, Mozambique
| | - Seydina O Sene
- Initiative Prospective Agricole et Rurale (IPAR), Dakar, Senegal
| | - Benedict Tuffuor
- Training Research and Networking for Development (TREND), Accra, Ghana
| | - Richard K Mugambe
- Department of Disease Control and Environmental Health, Makerere University School of Public Health, Kampala, Uganda
| | - Najib Lukooya Bateganya
- Department of Environment and Public Health, Kampala Capital City Authority, Kampala, Uganda
| | - Trevor Surridge
- Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH, Lusaka, Zambia
| | | | - Kunda Ndashe
- Department of Environmental Health, Faculty of Health Science, Lusaka Apex Medical University, Lusaka, Zambia
| | - Radu Ban
- Bill & Melinda Gates Foundation, Seattle, WA, USA
| | | | - Christine L Moe
- Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, GA, USA
| |
Collapse
|
2
|
Ogunrinu OJ, Norman KN, Vinasco J, Levent G, Lawhon SD, Fajt VR, Volkova VV, Gaire T, Poole TL, Genovese KJ, Wittum TE, Scott HM. Can the use of older-generation beta-lactam antibiotics in livestock production over-select for beta-lactamases of greatest consequence for human medicine? An in vitro experimental model. PLoS One 2020; 15:e0242195. [PMID: 33196662 PMCID: PMC7668573 DOI: 10.1371/journal.pone.0242195] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 10/29/2020] [Indexed: 12/16/2022] Open
Abstract
Though carbapenems are not licensed for use in food animals in the U.S., carbapenem resistance among Enterobacteriaceae has been identified in farm animals and their environments. The objective of our study was to determine the extent to which older-generation β-lactam antibiotics approved for use in food animals in the U.S. might differentially select for resistance to antibiotics of critical importance to human health, such as carbapenems. Escherichia coli (E. coli) strains from humans, food animals, or the environment bearing a single β-lactamase gene (n = 20 each) for blaTEM-1, blaCMY-2, and blaCTX-M-* or else blaKPC/IMP/NDM (due to limited availability, often in combination with other bla genes), were identified, along with 20 E. coli strains lacking any known beta-lactamase genes. Baseline estimates of intrinsic bacterial fitness were derived from the population growth curves. Effects of ampicillin (32 μg/mL), ceftriaxone (4 μg/mL) and meropenem (4 μg/mL) on each strain and resistance-group also were assessed. Further, in vitro batch cultures were prepared by mixing equal concentrations of 10 representative E. coli strains (two from each resistance gene group), and each mixture was incubated at 37°C for 24 hours in non-antibiotic cation-adjusted Mueller-Hinton II (CAMH-2) broth, ampicillin + CAMH-2 broth (at 2, 4, 8, 16, and 32 μg/mL) and ceftiofur + CAMH-2 broth (at 0.5, 1, 2, 4, and 8μg/mL). Relative and absolute abundance of resistance-groups were estimated phenotypically. Line plots of the raw data were generated, and non-linear Gompertz models and multilevel mixed-effect linear regression models were fitted to the data. The observed strain growth rate distributions were significantly different across the groups. AmpC strains (i.e., blaCMY-2) had distinctly less robust (p < 0.05) growth in ceftriaxone (4 μg/mL) compared to extended-spectrum beta-lactamase (ESBL) producers harboring blaCTX-M-*variants. With increasing beta-lactam antibiotic concentrations, relative proportions of ESBLs and CREs were over-represented in the mixed bacterial communities; importantly, this was more pronounced with ceftiofur than with ampicillin. These results indicate that aminopenicillins and extended-spectrum cephalosporins would be expected to propagate carbapenemase-producing Enterobacteriaceae in food animals if and when Enterobacteriaceae from human health care settings enter the food animal environment.
Collapse
Affiliation(s)
- Olanrewaju J. Ogunrinu
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America
| | - Keri N. Norman
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, United States of America
| | - Javier Vinasco
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America
| | - Gizem Levent
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America
| | - Sara D. Lawhon
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America
| | - Virginia R. Fajt
- Department of Veterinary Physiology & Pharmacology, Texas A&M University, College Station, Texas, United States of America
| | - Victoria V. Volkova
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas, United States of America
| | - Tara Gaire
- Department of Diagnostic Medicine/Pathobiology, Kansas State University, Manhattan, Kansas, United States of America
| | - Toni L. Poole
- Southern Plains Agricultural Research Center, United States Department of Agriculture, College Station, Texas, United States of America
| | - Kenneth J. Genovese
- Southern Plains Agricultural Research Center, United States Department of Agriculture, College Station, Texas, United States of America
| | - Thomas E. Wittum
- Department of Veterinary Preventive Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - H. Morgan Scott
- Department of Veterinary Pathobiology, Texas A&M University, College Station, Texas, United States of America
| |
Collapse
|
3
|
Thieme N, Panitz JC, Held C, Lewandowski B, Schwarz WH, Liebl W, Zverlov V. Milling byproducts are an economically viable substrate for butanol production using clostridial ABE fermentation. Appl Microbiol Biotechnol 2020; 104:8679-8689. [PMID: 32915256 PMCID: PMC7502454 DOI: 10.1007/s00253-020-10882-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/14/2020] [Accepted: 09/02/2020] [Indexed: 12/14/2022]
Abstract
Butanol is a platform chemical that is utilized in a wide range of industrial products and is considered a suitable replacement or additive to liquid fuels. So far, it is mainly produced through petrochemical routes. Alternative production routes, for example through biorefinery, are under investigation but are currently not at a market competitive level. Possible alternatives, such as acetone-butanol-ethanol (ABE) fermentation by solventogenic clostridia are not market-ready to this day either, because of their low butanol titer and the high costs of feedstocks. Here, we analyzed wheat middlings and wheat red dog, two wheat milling byproducts available in large quantities, as substrates for clostridial ABE fermentation. We could identify ten strains that exhibited good butanol yields on wheat red dog. Two of the best ABE producing strains, Clostridium beijerinckii NCIMB 8052 and Clostridium diolis DSM 15410, were used to optimize a laboratory-scale fermentation process. In addition, enzymatic pretreatment of both milling byproducts significantly enhanced ABE production rates of the strains C. beijerinckii NCIMB 8052 and C. diolis DSM 15410. Finally, a profitability analysis was performed for small- to mid-scale ABE fermentation plants that utilize enzymatically pretreated wheat red dog as substrate. The estimations show that such a plant could be commercially successful.Key points• Wheat milling byproducts are suitable substrates for clostridial ABE fermentation.• Enzymatic pretreatment of wheat red dog and middlings increases ABE yield.• ABE fermentation plants using wheat red dog as substrate are economically viable. Graphical abstract.
Collapse
Affiliation(s)
- Nils Thieme
- Technical University of Munich, Emil-Ramann-Str. 4, 85354, Freising, Germany
| | - Johanna C Panitz
- Technical University of Munich, Emil-Ramann-Str. 4, 85354, Freising, Germany
- Technical University of Munich, Weihenstephaner Berg 3, 85354, Freising, Germany
| | - Claudia Held
- Technical University of Munich, Emil-Ramann-Str. 4, 85354, Freising, Germany
- TDK Electronics AG, Rosenheimer Str. 141e, 81671, Munich, Germany
| | - Birgit Lewandowski
- Fritzmeier Umwelttechnik GmbH & Co KG, Dorfstraße 7, 85653, Aying, Germany
- Electrochaea GmbH, Semmelweisstrasse 3, 82152, Planegg, Germany
| | - Wolfgang H Schwarz
- Technical University of Munich, Emil-Ramann-Str. 4, 85354, Freising, Germany
- aspratis GmbH, Huebnerstrasse 11, 80637, Munich, Germany
| | - Wolfgang Liebl
- Technical University of Munich, Emil-Ramann-Str. 4, 85354, Freising, Germany
| | - Vladimir Zverlov
- Technical University of Munich, Emil-Ramann-Str. 4, 85354, Freising, Germany.
- Institute of Molecular Genetics, RAS, Kurchatov Sq 2, 123128, Moscow, Russia.
| |
Collapse
|
4
|
Patterns of Lignocellulosic Sugar Assimilation and Lipid Production by Newly Isolated Yeast Strains From Chilean Valdivian Forest. Appl Biochem Biotechnol 2020; 192:1124-1146. [PMID: 32700200 DOI: 10.1007/s12010-020-03398-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 07/16/2020] [Indexed: 12/19/2022]
Abstract
Three yeast strains were isolated from decaying wood of Chilean Valdivian forest and identified as Meyerozyma guilliermondii, Scheffersomyces coipomensis, and Sugiyamaella paludigena. These strains were able to efficiently grow on the major monomers contained in Pinus spp. and Eucalyptus spp. wood that includes glucose (Glc), xylose (Xyl), and mannose (Man), showing at 28 °C higher uptake rates for Man, and in some cases for Glc, than for Xyl, used as single carbon sources. Nevertheless, in cultures performed on sugar mixtures, the strains displayed a notable preference for Glc. Additionally, in sugar mixtures, the absence of regulatory mechanisms in sugar assimilation (e.g., catabolic repression) was observed and documented when the activities of several enzymes involved in sugar assimilation (i.e., phosphoglucose isomerase, phosphomannose isomerase, and xylulokinase) were determined. The activity of the key enzymes involved in the onset of lipid accumulation (i.e., NAD+-ICDH) and in fatty acid (FA) biosynthesis (i.e., ATP:CL) indicated a significant accumulation of storage lipids (i.e., up to 24%, w/w) containing oleic and palmitic acids as the major components. The present paper is the first report on the potential of M. guilliermondii, S. coipomensis, and S. paludigena as oleaginous yeasts. We conclude that the new isolates, being able to simultaneously assimilate the major lignocellulosic sugars and efficiently convert them into oily biomass, present a biotechnological potential which deserve further investigation.
Collapse
|
5
|
Sargeant LA, Mardell M, Saad‐Allah KM, Hussein AH, Whiffin F, Santomauro F, Chuck CJ. Production of lipid from depolymerised lignocellulose using the biocontrol yeast,
Rhodotorula minuta
: The fatty acid profile remains stable irrespective of environmental conditions. EUR J LIPID SCI TECH 2015. [DOI: 10.1002/ejlt.201500143] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Lisa A. Sargeant
- Doctoral Training Centre in Sustainable Chemical Technologies, Department of Chemical EngineeringUniversity of BathBathUnited Kingdom
| | - Matthew Mardell
- Department of Chemical EngineeringUniversity of BathBathUnited Kingdom
| | | | - Ali H. Hussein
- Department of Biology and BiochemistryUniversity of BathBathUnited Kingdom
| | - Fraeya Whiffin
- Doctoral Training Centre in Sustainable Chemical Technologies, Department of Chemical EngineeringUniversity of BathBathUnited Kingdom
| | - Fabio Santomauro
- Department of Chemical EngineeringUniversity of BathBathUnited Kingdom
| | | |
Collapse
|
6
|
Wang C, Cai H, Zhou Z, Zhang K, Chen Z, Chen Y, Wan H, Ouyang P. Investigation of ptsG gene in response to xylose utilization in Corynebacterium glutamicum. J Ind Microbiol Biotechnol 2014; 41:1249-58. [PMID: 24859809 DOI: 10.1007/s10295-014-1455-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 04/28/2014] [Indexed: 11/26/2022]
Abstract
Corynebacterium glutamicum strains NC-2 were able to grow on xylose as sole carbon sources in our previous work. Nevertheless, it exhibited the major shortcoming that the xylose consumption was repressed in the presence of glucose. So far, regarding C. glutamicum, there are a number of reports on ptsG gene, the glucose-specific transporter, involved in glucose metabolism. Recently, we found ptsG had influence on xylose utilization and investigated the ptsG gene in response to xylose utilization in C. glutamicum with the aim to improve xylose consumption and simultaneously utilized glucose and xylose. The ptsG-deficient mutant could grow on xylose, while exhibiting noticeably reduced growth on xylose as sole carbon source. A mutant deficient in ptsH, a general PTS gene, exhibited a similar phenomenon. When complementing ptsG gene, the mutant ΔptsG-ptsG restored the ability to grow on xylose similarly to NC-2. These indicate that ptsG gene is not only essential for metabolism on glucose but also important in xylose utilization. A ptsG-overexpressing recombinant strain could not accelerate glucose or xylose metabolism. When strains were aerobically cultured in a sugar mixture of glucose and xylose, glucose and xylose could not be utilized simultaneously. Interestingly, the ΔptsG strain could co-utilize glucose and xylose under oxygen-deprived conditions, though the consumption rate of glucose and xylose dramatically declined. It was the first report of ptsG gene in response to xylose utilization in C. glutamicum.
Collapse
Affiliation(s)
- Chen Wang
- College of Biotechnology and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing, 211816, China
| | | | | | | | | | | | | | | |
Collapse
|
7
|
Hu C, Wu S, Wang Q, Jin G, Shen H, Zhao ZK. Simultaneous utilization of glucose and xylose for lipid production by Trichosporon cutaneum. BIOTECHNOLOGY FOR BIOFUELS 2011; 4:25. [PMID: 21864398 PMCID: PMC3174874 DOI: 10.1186/1754-6834-4-25] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2011] [Accepted: 08/24/2011] [Indexed: 05/05/2023]
Abstract
BACKGROUND Biochemical conversion of lignocellulose hydrolysates remains challenging, largely because most microbial processes have markedly reduced efficiency in the presence of both hexoses and pentoses. Thus, identification of microorganisms capable of efficient and simultaneous utilization of both glucose and xylose is pivotal to improving this process. RESULTS In this study, we found that the oleaginous yeast strain Trichosporon cutaneum AS 2.571 assimilated glucose and xylose simultaneously, and accumulated intracellular lipid up to 59 wt% with a lipid coefficient up to 0.17 g/g sugar, upon cultivation on a 2:1 glucose/xylose mixture in a 3-liter stirred-tank bioreactor. In addition, no classic pattern of diauxic growth behavior was seen; the microbial cell mass increased during the whole culture process without any lag periods. In shake-flask cultures with different initial glucose:xylose ratios, glucose and xylose were consumed simultaneously at rates roughly proportional to their individual concentrations in the medium, leading to complete utilization of both sugars at the same time. Simultaneous utilization of glucose and xylose was also seen during fermentation of corn-stover hydrolysate with a lipid content and coefficient of 39.2% and 0.15 g/g sugar, respectively. The lipid produced had a fatty-acid compositional profile similar to those of conventional vegetable oil, indicating that it could have potential as a raw material for biodiesel production. CONCLUSION Efficient lipid production with simultaneous consumption of glucose and xylose was achieved in this study. This process provides an exciting opportunity to transform lignocellulosic materials into biofuel molecules, and should also encourage further study to elucidate this unique sugar-assimilation mechanism.
Collapse
Affiliation(s)
- Cuimin Hu
- Dalian Institute of Chemical Physics, CAS, Dalian 116023, China
- Graduate University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Siguo Wu
- Dalian Institute of Chemical Physics, CAS, Dalian 116023, China
| | - Qian Wang
- Dalian Institute of Chemical Physics, CAS, Dalian 116023, China
| | - Guojie Jin
- Dalian Institute of Chemical Physics, CAS, Dalian 116023, China
- Graduate University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Hongwei Shen
- Dalian Institute of Chemical Physics, CAS, Dalian 116023, China
| | - Zongbao K Zhao
- Dalian Institute of Chemical Physics, CAS, Dalian 116023, China
- Dalian National Laboratory for Clean Energy, Dalian 116023, China
| |
Collapse
|
8
|
Thermophilic, lignocellulolytic bacteria for ethanol production: current state and perspectives. Appl Microbiol Biotechnol 2011; 92:13-27. [DOI: 10.1007/s00253-011-3456-3] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 06/15/2011] [Accepted: 06/15/2011] [Indexed: 10/17/2022]
|
9
|
Tangney M, Brehm JK, Minton NP, Mitchell WJ. A gene system for glucitol transport and metabolism in Clostridium beijerinckii NCIMB 8052. Appl Environ Microbiol 1998; 64:1612-9. [PMID: 9572925 PMCID: PMC106204 DOI: 10.1128/aem.64.5.1612-1619.1998] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The gutD gene of Clostridium beijerinckii NCIMB 8052 encoding glucitol 6-phosphate dehydrogenase was cloned on a 5.7-kbp chromosomal DNA fragment by complementing an Escherichia coli gutD mutant strain and selecting for growth on glucitol. Five open reading frames (ORFs) in the order gutA1 gutA2 orfX gutB gutD were identified in a 4.0-kbp region of the cloned DNA. The deduced products of four of these ORFs were homologous to components of the glucitol phosphotransferase system (PTS) and glucitol 6-phosphate dehydrogenase from E. coli, while the remaining ORF (orfX) encoded an enzyme which had similarities to members of a family of transaldolases. A strain in which gutD was inactivated by targeted integration lacked glucitol 6-phosphate dehydrogenase activity. The gutA1 and gutA2 genes encoded two polypeptides forming enzyme IIBC of the glucitol PTS comprising three domains in the order CBC. Domain IIA of the glucitol PTS was encoded by gutB. Glucitol phosphorylation assays in which soluble and membrane fractions of cells grown on glucose (which did not synthesize the glucitol PTS) or cells grown on glucitol were used confirmed that there is a separate, soluble, glucitol-specific PTS component, which is the product of the gutB gene. The gut genes were regulated at the level of transcription and were induced in the presence of glucitol. Cells grown in the presence of glucose and glucitol utilized glucose preferentially. Following depletion of glucose, the glucitol PTS and glucitol 6-phosphate dehydrogenase were synthesized, and glucitol was removed from the culture medium. RNA analysis showed that the gut genes were not expressed until glucose was depleted.
Collapse
Affiliation(s)
- M Tangney
- Department of Biological Sciences, Heriot-Watt University, Riccarton, Edinburgh, United Kingdom
| | | | | | | |
Collapse
|
10
|
Abstract
The solvent-forming clostridia have attracted interest because of their ability to convert a range of carbohydrates to end-products such as acetone, butanol and ethanol. Polymeric substrates such as cellulose, hemicellulose and starch are degraded by extracellular enzymes. The majority of cellulolytic clostridia, typified by Clostridium thermocellum, produce a multi-enzyme cellulase complex in which the organization of components is critical for activity against the crystalline substrate. A variety of enzymes involved in degradation of hemicellulose and starch have been identified in different strains. The products of degradation, and other soluble substrates, are accumulated via membrane-bound transport systems which are generally poorly characterized. It is clear, however, that the phosphoenolpyruvate-dependent phosphotransferase system (PTS) plays a major role in solute uptake in several species. Accumulated substrates are converted by intracellular enzymes to end-products characteristic of the organism, with production of ATP to support growth. The metabolic pathways have been described, but understanding of mechanisms of regulation of metabolism is incomplete. Synthesis of extracellular enzymes and membrane-bound transport systems is commonly subject to catabolite repression in the presence of a readily metabolized source of carbon and energy. While many genes encoding cellulases, xylanases and amylases have been cloned and sequenced, little is known of control of their expression. Although the mechanism of catabolite repression in clostridia is not understood, some recent findings implicate a role for the PTS as in other low G-C Gram-positive bacteria. Emphasis has been placed on describing the mechanisms underlying the switch of C. acetobutylicum fermentations from acidogenic to solventogenic metabolism at the end of the growth phase. Factors involved include a lowered pH and accumulation of undissociated butyric acid, intracellular concentration of ATP and reduced pyridine nucleotides, nutrient limitation, and the interplay between pathways of carbon and electron flow. Genes encoding enzymes of solvent pathways have been cloned and sequenced, and their expression correlated with the pattern of end-product formation in fermentations. There is evidence that the initiation of solvent formation may be subject to control mechanisms similar to other stationary-phase phenomena, including sporulation. The application of recently developed techniques for genetic manipulation of the bacterium is improving understanding of the regulatory circuits, but a complete molecular description of the control of solvent formation remains elusive. Experimental manipulation of the pathways of electron flow in other species has been shown to influence the range and yield of fermentation end-products. Acid-forming clostridia can, under appropriate conditions, be induced to form atypical solvents as products. While the mechanisms of regulation of gene expression are not at all understood, the capacity to adapt in this way further illustrates the metabolic flexibility of clostridial strains.
Collapse
Affiliation(s)
- W J Mitchell
- Department of Biological Sciences, Heriot-Watt University, Edinburgh, UK
| |
Collapse
|
11
|
Mitchell WJ, Albasheri KA, Yazdanian M. Factors affecting utilization of carbohydrates by clostridia. FEMS Microbiol Rev 1995. [DOI: 10.1111/j.1574-6976.1995.tb00215.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
|
12
|
Meaden PG, Aduse-Opoku J, Reizer J, Reizer A, Lanceman YA, Martin MF, Mitchell WJ. The xylose isomerase-encoding gene (xylA) of Clostridium thermosaccharolyticum: cloning, sequencing and phylogeny of XylA enzymes. Gene 1994; 141:97-101. [PMID: 8163183 DOI: 10.1016/0378-1119(94)90134-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The xylose isomerase (XylA)-encoding gene (xylA) of the thermophilic anaerobic bacterium, Clostridium thermosaccharolyticum NCIB 9385, was cloned as a 4.0-kb DNA fragment by complementation of the Escherichia coli xylA mutant strain, DS941. The open reading frame of 1317 bp encoded a protein of 439 amino acids (aa), with a calculated M(r) of 50,236. The gene was preceeded by a typical clostridial Shine-Dalgarno sequence, and was expressed constitutively in the cloning host. Downstream, the clone appeared to carry a xylB gene (encoding xylulokinase) in the same orientation as xylA. Comparison of the deduced aa sequence of the C. thermosaccharolyticum XylA with 18 other XylA showed that this family of proteins was separated into two clusters, one comprising proteins from organisms with G + C-rich DNA, and the other proteins from organisms with a lower G + C composition. Within the second cluster, the XylA of C. thermosaccharolyticum was most closely related to the enzymes from C. thermosulfurogenes (Thermoanaerobacterium thermosulfurigenes) and C. thermohydrosulfuricum (93 and 84% identity, respectively). Analysis of the aligned sequences indicated two signatures (VXW[GP]GREG[YSTA]E and [LIVM]EPKPX]EQ]P) which may be useful in isolation of novel XylA.
Collapse
Affiliation(s)
- P G Meaden
- Department of Biological Sciences, Heriot-Watt University, Edinburgh, UK
| | | | | | | | | | | | | |
Collapse
|
13
|
Marounek M, Kopecný J. Utilization of Glucose and Xylose in Ruminal Strains of
Butyrivibrio fibrisolvens. Appl Environ Microbiol 1994; 60:738-9. [PMID: 16349201 PMCID: PMC201376 DOI: 10.1128/aem.60.2.738-739.1994] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The dual-substrate utilization pattern in cultures of five ruminal strains of
Butyrivibrio fibrisolvens
growing on glucose and xylose was investigated. Strains ATCC 19171 and 86 utilized glucose and xylose simultaneously. Other strains exhibited diauxic growth. Strains X1 and CE 51 exhibited classical diauxic growth in which glucose was utilized during the first phase. Strain X2D62 displayed atypical diauxic growth in which slow utilization of xylose was followed by rapid utilization of glucose after the xylose depletion. The ATP-dependent phosphorylation of glucose was found in all strains tested. The phosphoenolpyruvate-dependent phosphorylation of glucose was detected only in
B. fibrisolvens
CE 51.
Collapse
Affiliation(s)
- M Marounek
- Institute of Animal Physiology and Genetics, Czech Academy of Sciences, 104 00 Prague 10, Uhríneves, Czech Republic
| | | |
Collapse
|
14
|
Cook GM, Janssen PH, Morgan HW. Simultaneous uptake and utilisation of glucose and xylose byClostridium thermohydrosulfuricum. FEMS Microbiol Lett 1993. [DOI: 10.1111/j.1574-6968.1993.tb06143.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
|
15
|
Affiliation(s)
- W J Mitchell
- Department of Biological Sciences, Heriot-Watt University, Riccarton, Edinburgh, UK
| |
Collapse
|