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Herrero OM, Alvarez HM. Fruit residues as substrates for single-cell oil production by Rhodococcus species: physiology and genomics of carbohydrate catabolism. World J Microbiol Biotechnol 2024; 40:61. [PMID: 38177966 DOI: 10.1007/s11274-023-03866-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 12/03/2023] [Indexed: 01/06/2024]
Abstract
Strains belonging to R. opacus, R. jostii, R. fascians, R. erythropolis and R. equi exhibited differential ability to grow and produce lipids from fruit residues (grape marc and apple pomace), as well as single carbohydrates, such as glucose, gluconate, fructose and sucrose. The oleaginous species, R. opacus (strains PD630 and MR22) and R. jostii RHA1, produced higher yields of biomass (5.1-5.6 g L-1) and lipids (38-44% of CDW) from apple juice wastes, in comparison to R. erythropolis DSM43060, R. fascians F7 and R. equi ATCC6939 (4.1-4.3 g L-1 and less than 10% CDW of lipids). The production of cellular biomass and lipids were also higher in R. opacus and R. jostii (6.8-7.2 g L-1 and 33.9-36.5% of CDW of lipids) compared to R. erythropolis, R. fascians, and R. equi (3.0-3.6 g L-1 and less than 10% CDW of lipids), during cultivation of cells on wine grape waste. A genome-wide bioinformatic analysis of rhodococci indicated that oleaginous species possess a complete set of genes/proteins necessary for the efficient utilization of carbohydrates, whereas genomes from non-oleaginous rhodococcal strains lack relevant genes coding for transporters and/or enzymes for the uptake, catabolism and assimilation of carbohydrates, such as gntP, glcP, edd, eda, among others. Results of this study highlight the potential use of the oleaginous rhodococcal species to convert sugar-rich agro-industrial wastes, such as apple pomace and grape marc, into single-cell oils.
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Affiliation(s)
- O Marisa Herrero
- Instituto de Biociencias de la Patagonia (INBIOP), Universidad Nacional de la Patagonia San Juan Bosco y CONICET, Km 4-Ciudad Universitaria, 9000, Comodoro Rivadavia, Chubut, Argentina
| | - Héctor M Alvarez
- Instituto de Biociencias de la Patagonia (INBIOP), Universidad Nacional de la Patagonia San Juan Bosco y CONICET, Km 4-Ciudad Universitaria, 9000, Comodoro Rivadavia, Chubut, Argentina.
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Presentato A, Piacenza E, Cappelletti M, Turner RJ. Interaction of Rhodococcus with Metals and Biotechnological Applications. BIOLOGY OF RHODOCOCCUS 2019. [DOI: 10.1007/978-3-030-11461-9_12] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Herrero OM, Villalba MS, Lanfranconi MP, Alvarez HM. Rhodococcus bacteria as a promising source of oils from olive mill wastes. World J Microbiol Biotechnol 2018; 34:114. [DOI: 10.1007/s11274-018-2499-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 07/07/2018] [Indexed: 10/28/2022]
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Presentato A, Piacenza E, Anikovskiy M, Cappelletti M, Zannoni D, Turner RJ. Rhodococcus aetherivorans BCP1 as cell factory for the production of intracellular tellurium nanorods under aerobic conditions. Microb Cell Fact 2016; 15:204. [PMID: 27978836 PMCID: PMC5157098 DOI: 10.1186/s12934-016-0602-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 11/24/2016] [Indexed: 01/05/2023] Open
Abstract
Background Tellurite (TeO32−) is recognized as a toxic oxyanion to living organisms. However, mainly anaerobic or facultative-anaerobic microorganisms are able to tolerate and convert TeO32− into the less toxic and available form of elemental Tellurium (Te0), producing Te-deposits or Te-nanostructures. The use of TeO32−-reducing bacteria can lead to the decontamination of polluted environments and the development of “green-synthesis” methods for the production of nanomaterials. In this study, the tolerance and the consumption of TeO32− have been investigated, along with the production and characterization of Te-nanorods by Rhodococcus aetherivorans BCP1 grown under aerobic conditions. Results Aerobically grown BCP1 cells showed high tolerance towards TeO32− with a minimal inhibitory concentration (MIC) of 2800 μg/mL (11.2 mM). TeO32− consumption has been evaluated exposing the BCP1 strain to either 100 or 500 μg/mL of K2TeO3 (unconditioned growth) or after re-inoculation in fresh medium with new addition of K2TeO3 (conditioned growth). A complete consumption of TeO32− at 100 μg/mL was observed under both growth conditions, although conditioned cells showed higher consumption rate. Unconditioned and conditioned BCP1 cells partially consumed TeO32− at 500 μg/mL. However, a greater TeO32− consumption was observed with conditioned cells. The production of intracellular, not aggregated and rod-shaped Te-nanostructures (TeNRs) was observed as a consequence of TeO32− reduction. Extracted TeNRs appear to be embedded in an organic surrounding material, as suggested by the chemical–physical characterization. Moreover, we observed longer TeNRs depending on either the concentration of precursor (100 or 500 μg/mL of K2TeO3) or the growth conditions (unconditioned or conditioned grown cells). Conclusions Rhodococcus aetherivorans BCP1 is able to tolerate high concentrations of TeO32− during its growth under aerobic conditions. Moreover, compared to unconditioned BCP1 cells, TeO32−conditioned cells showed a higher oxyanion consumption rate (for 100 μg/mL of K2TeO3) or to consume greater amount of TeO32− (for 500 μg/mL of K2TeO3). TeO32− consumption by BCP1 cells led to the production of intracellular and not aggregated TeNRs embedded in an organic surrounding material. The high resistance of BCP1 to TeO32− along with its ability to produce Te-nanostructures supports the application of this microorganism as a possible eco-friendly nanofactory. Electronic supplementary material The online version of this article (doi:10.1186/s12934-016-0602-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alessandro Presentato
- Microbial Biochemistry Laboratory, Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4, Canada.
| | - Elena Piacenza
- Microbial Biochemistry Laboratory, Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4, Canada
| | - Max Anikovskiy
- Department of Chemistry, University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4, Canada
| | - Martina Cappelletti
- Department of Pharmacy and Biotechnology, Unit of General and Applied Microbiology, Via Irnerio 42, Bologna, 40126, Italy
| | - Davide Zannoni
- Department of Pharmacy and Biotechnology, Unit of General and Applied Microbiology, Via Irnerio 42, Bologna, 40126, Italy
| | - Raymond J Turner
- Microbial Biochemistry Laboratory, Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4, Canada.
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Castro AR, Rocha I, Alves MM, Pereira MA. Rhodococcus opacus B4: a promising bacterium for production of biofuels and biobased chemicals. AMB Express 2016; 6:35. [PMID: 27179529 PMCID: PMC4870530 DOI: 10.1186/s13568-016-0207-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 05/07/2016] [Indexed: 11/10/2022] Open
Abstract
Bacterial lipids have relevant applications in the production of renewable fuels and biobased oleochemicals. The genus Rhodococcus is one of the most relevant lipid producers due to its capability to accumulate those compounds, mainly triacylglycerols (TAG), when cultivated on different defined substrates, namely sugars, organic acids and hydrocarbons but also on complex carbon sources present in industrial wastes. In this work, the production of storage lipids by Rhodococcus opacus B4 using glucose, acetate and hexadecane is reported for the first time and its productivity compared with Rhodococcus opacus PD630, the best TAG producer bacterium reported. Both strains accumulated mainly TAG from all carbon sources, being influenced by the carbon source itself and by the duration of the accumulation period. R. opacus B4 produced 0.09 and 0.14 g L(-1) at 24 and 72 h, with hexadecane as carbon source, which was 2 and 3.3 fold higher than the volumetric production obtained by R. opacus PD630. Both strains presented similar fatty acids (FA) profiles in intact cells while in TAG produced fraction, R. opacus B4 revealed a higher variability in fatty acid composition than R. opacus PD630, when both strains were cultivated on hexadecane. The obtained results open new perspectives for the use of R. opacus B4 to produce TAG, in particular using oily (alkane-contaminated) waste and wastewater as cheap raw-materials. Combining TAG production with hydrocarbons degradation is a promising strategy to achieve environmental remediation while producing added value compounds.
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Hernández MA, Lara J, Gago G, Gramajo H, Alvarez HM. The pleiotropic transcriptional regulator NlpR contributes to the modulation of nitrogen metabolism, lipogenesis and triacylglycerol accumulation in oleaginous rhodococci. Mol Microbiol 2016; 103:366-385. [DOI: 10.1111/mmi.13564] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/22/2016] [Indexed: 01/04/2023]
Affiliation(s)
- Martín A. Hernández
- INBIOP (Instituto de Biociencias de la Patagonia), Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Naturales; Universidad Nacional de la Patagonia San Juan Bosco; Ruta Provincial N° 1, Km 4-Ciudad Universitaria 9000 Comodoro Rivadavia Chubut Argentina
| | - Julia Lara
- IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas. Facultad de Ciencias Bioquímicas y Farmacéuticas; Universidad Nacional de Rosario; Ocampo y Esmeralda 2000 Rosario Santa Fe Argentina
| | - Gabriela Gago
- IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas. Facultad de Ciencias Bioquímicas y Farmacéuticas; Universidad Nacional de Rosario; Ocampo y Esmeralda 2000 Rosario Santa Fe Argentina
| | - Hugo Gramajo
- IBR (Instituto de Biología Molecular y Celular de Rosario), Consejo Nacional de Investigaciones Científicas y Técnicas. Facultad de Ciencias Bioquímicas y Farmacéuticas; Universidad Nacional de Rosario; Ocampo y Esmeralda 2000 Rosario Santa Fe Argentina
| | - Héctor M. Alvarez
- INBIOP (Instituto de Biociencias de la Patagonia), Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Naturales; Universidad Nacional de la Patagonia San Juan Bosco; Ruta Provincial N° 1, Km 4-Ciudad Universitaria 9000 Comodoro Rivadavia Chubut Argentina
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Khairy H, Wübbeler JH, Steinbüchel A. The NADH:flavin oxidoreductase Nox from Rhodococcus erythropolis MI2 is the key enzyme of 4,4'-dithiodibutyric acid degradation. Lett Appl Microbiol 2016; 63:434-441. [PMID: 27564089 DOI: 10.1111/lam.12662] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 07/14/2016] [Accepted: 08/20/2016] [Indexed: 11/30/2022]
Abstract
The reduction of the disulphide bond is the initial catabolic step of the microbial degradation of the organic disulphide 4,4'-dithiodibutyric acid (DTDB). Previously, an NADH:flavin oxidoreductase from Rhodococcus erythropolis MI2 designated as NoxMI2 , which belongs to the old yellow enzyme (OYE) family, was identified. In the present study, it was proven that NoxMI2 has the ability to cleave the sulphur-sulphur bond in DTDB. In silico analysis revealed high sequence similarities to proteins of the flavin mononucleotide (FMN) reductase family identified in many strains of R. erythropolis. Therefore, nox was heterologously expressed in the pET23a(+) expression system using Escherichia coli strain BL21(DE3) pLysS, which effectively produces soluble active NoxMI2 . NoxMI2 showed a maximum specific activity (Vmax ) of 3·36 μmol min-1 mg-1 corresponding to a kcat of 2·5 s-1 and an apparent substrate Km of 0·6 mmol l-1 , when different DTDB concentrations were applied. No metal cofactors were required. Moreover, NoxMI2 had very low activity with other sulphur-containing compounds like 3,3'-dithiodipropionic acid (8·0%), 3,3'-thiodipropionic acid (7·6%) and 5,5'-dithiobis(2-nitrobenzoic acid) (8·0%). The UV/VIS spectrum of NoxMI2 revealed the presence of the cofactor FMN. Based on results obtained, NoxMI2 adds a new physiological substrate and mode of action to OYE members. SIGNIFICANCE AND IMPACT OF THE STUDY It was unequivocally demonstrated in this study that an NADH:flavin oxidoreductase from Rhodococcus erythropolis MI2 (NoxMI2 ) is able to cleave the xenobiotic disulphide 4,4'-dithiodibutyric acid (DTDB) into two molecules of 4-mercaptobutyric acid (4MB) with concomitant consumption of NADH. NoxMI2 showed a high substrate specificity as well as high heat stability. This study provides the first detailed characterization of the initial cleavage of DTDB, which is considered as a promising polythioester precursor.
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Affiliation(s)
- H Khairy
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster, Germany.,Botany and Microbiology Department, Faculty of Science, Alexandria University, Alexandria, Egypt
| | - J H Wübbeler
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - A Steinbüchel
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster, Germany.,Faculty of Environmental Sciences, King Abdulaziz University, Jeddah, Saudi Arabia
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Herrero OM, Moncalián G, Alvarez HM. Physiological and genetic differences amongst Rhodococcus species for using glycerol as a source for growth and triacylglycerol production. Microbiology (Reading) 2016; 162:384-397. [DOI: 10.1099/mic.0.000232] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- O. Marisa Herrero
- Centro Regional de Investigación y Desarrollo Científico Tecnológico, Facultad de Ciencias Naturales,Universidad Nacional de la Patagonia San Juan Bosco y CIT-CHUBUT CONICET, Km 4-Ciudad Universitaria, 9000 Comodoro Rivadavia (Chubut), Argentina
- Oil m&s, Avenida Hipólito Yrigoyen 4250, 9000 Comodoro Rivadavia (Chubut), Argentina
| | - Gabriel Moncalián
- Departamento de Biología Molecular e Instituto de Biomedicina y Biotecnología de Cantabria,Universidad de Cantabria-Consejo Superior de Investigaciones Científicas-SODERCAN, Calle Albert Einstein 22, 39011 Santander,Spain
| | - Héctor M. Alvarez
- Centro Regional de Investigación y Desarrollo Científico Tecnológico, Facultad de Ciencias Naturales,Universidad Nacional de la Patagonia San Juan Bosco y CIT-CHUBUT CONICET, Km 4-Ciudad Universitaria, 9000 Comodoro Rivadavia (Chubut), Argentina
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Lanfranconi MP, Alvarez AF, Alvarez HM. Identification of genes coding for putative wax ester synthase/diacylglycerol acyltransferase enzymes in terrestrial and marine environments. AMB Express 2015; 5:128. [PMID: 26228353 PMCID: PMC4520822 DOI: 10.1186/s13568-015-0128-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 07/06/2015] [Indexed: 11/29/2022] Open
Abstract
Synthesis of neutral lipids such as triacylglycerols (TAG) and wax esters (WE) is catalyzed in bacteria by wax ester synthase/diacylglycerol acyltransferase enzymes (WS/DGAT). We investigated
the diversity of genes encoding this enzyme in contrasting natural environments from Patagonia (Argentina). The content of petroleum hydrocarbons in samples collected from oil-producing areas was measured. PCR-based analysis covered WS/DGAT occurrence in marine sediments and soil. No product was obtained in seawater samples. All clones retrieved from marine sediments affiliated with gammaproteobacterial sequences and within them, most phylotypes formed a unique cluster related to putative WS/DGAT belonging to marine OM60 clade. In contrast, soils samples contained phylotypes only related to actinomycetes. Among them, phylotypes affiliated with representatives largely or recently reported as oleaginous bacteria, as well as with others considered as possible lipid-accumulating bacteria based on the analysis of their annotated genomes. Our study shows for the first time that the environment could contain a higher variety of ws/dgat than that reported from bacterial isolates. The results of this study highlight the relevance of the environment in a natural process such as the synthesis and accumulation of neutral lipids. Particularly, both marine sediments and soil may serve as a useful source for novel WS/DGAT with biotechnological interest.
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Dávila Costa JS, Leichert L, Alvarez HM, Herrero OM. Label-free and redox proteomic analyses of the triacylglycerol-accumulating Rhodococcus jostii RHA1. Microbiology (Reading) 2015; 161:593-610. [DOI: 10.1099/mic.0.000028] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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Hernández MA, Comba S, Arabolaza A, Gramajo H, Alvarez HM. Overexpression of a phosphatidic acid phosphatase type 2 leads to an increase in triacylglycerol production in oleaginous Rhodococcus strains. Appl Microbiol Biotechnol 2014; 99:2191-207. [PMID: 25213912 DOI: 10.1007/s00253-014-6002-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 07/30/2014] [Accepted: 07/31/2014] [Indexed: 01/28/2023]
Abstract
Oleaginous Rhodococcus strains are able to accumulate large amounts of triacylglycerol (TAG). Phosphatidic acid phosphatase (PAP) enzyme catalyzes the dephosphorylation of phosphatidic acid (PA) to yield diacylglycerol (DAG), a key precursor for TAG biosynthesis. Studies to establish its role in lipid metabolism have been mainly focused in eukaryotes but not in bacteria. In this work, we identified and characterized a putative PAP type 2 (PAP2) encoded by the ro00075 gene in Rhodococcus jostii RHA1. Heterologous expression of ro00075 in Escherichia coli resulted in a fourfold increase in PAP activity and twofold in DAG content. The conditional deletion of ro00075 in RHA1 led to a decrease in the content of DAG and TAG, whereas its overexpression in both RHA1 and Rhodococcus opacus PD630 promoted an increase up to 10 to 15 % by cellular dry weight in TAG content. On the other hand, expression of ro00075 in the non-oleaginous strain Rhodococcus fascians F7 promoted an increase in total fatty acid content up to 7 % at the expense of free fatty acid (FFA), DAG, and TAG fractions. Moreover, co-expression of ro00075/atf2 genes resulted in a fourfold increase in total fatty acid content by a further increase of the FFA and TAG fractions. The results of this study suggest that ro00075 encodes for a PAP2 enzyme actively involved in TAG biosynthesis. Overexpression of this gene, as single one or with an atf gene, provides an alternative approach to increase the biosynthesis and accumulation of bacterial oils as a potential source of raw material for biofuel production.
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Affiliation(s)
- Martín A Hernández
- Centro Regional de Investigación y Desarrollo Científico Tecnológico, Facultad de Ciencias Naturales, Universidad Nacional de la Patagonia San Juan Bosco, Ruta Provincial N° 1, Km 4-Ciudad Universitaria, 9000, Comodoro Rivadavia, Chubut, Argentina
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Identification of a novel ATP-binding cassette transporter involved in long-chain fatty acid import and its role in triacylglycerol accumulation in Rhodococcus jostii RHA1. Microbiology (Reading) 2014; 160:1523-1532. [DOI: 10.1099/mic.0.078477-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Members of the genus Rhodococcus are specialists in the biosynthesis and accumulation of triacylglycerols (TAGs). As no transport protein related to TAG metabolism has yet been characterized in these bacteria, we used the available genomic information of Rhodococcus jostii RHA1 to perform a broad survey of genes coding for putative lipid transporter proteins in this oleaginous micro-organism. Among the seven genes encoding putative lipid transporters, ro05645 (now called ltp1: lipid transporter protein) coding for an ATP-binding cassette protein was found clustered with others genes encoding enzymes catalysing the three putative acylation reactions of the Kennedy pathway for TAG synthesis. Overexpression of ltp1 in the RHA1 strain led to an increase of approximately sixfold and threefold in biomass and TAG production, respectively, when cells were cultivated on palmitic acid and oleic acid. Moreover, overexpression of ltp1 also promoted a significant increase in the uptake of a fluorescently labelled long-chain fatty acid (LCFA), as compared with the WT strain RHA1, and its further incorporation into the TAG fraction. Gluconate-grown cells showed increasing amounts of intracellular free fatty acids, but not of TAG, after overexpressing ltp1. Thus, for the first time to our knowledge, a transporter functionally related to TAG metabolism was identified in oleaginous rhodococci. Our results suggested that Ltp1 is an importer of LCFAs that plays a functional role in lipid homeostasis of R. jostii RHA1.
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Urbano SB, Di Capua C, Cortez N, Farías ME, Alvarez HM. Triacylglycerol accumulation and oxidative stress in Rhodococcus species: differential effects of pro-oxidants on lipid metabolism. Extremophiles 2014; 18:375-84. [DOI: 10.1007/s00792-013-0623-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 12/29/2013] [Indexed: 11/28/2022]
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Kurosawa K, Wewetzer SJ, Sinskey AJ. Engineering xylose metabolism in triacylglycerol-producing Rhodococcus opacus for lignocellulosic fuel production. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:134. [PMID: 24041310 PMCID: PMC3848844 DOI: 10.1186/1754-6834-6-134] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Accepted: 08/27/2013] [Indexed: 05/04/2023]
Abstract
BACKGROUND There has been a great deal of interest in fuel productions from lignocellulosic biomass to minimize the conflict between food and fuel use. The bioconversion of xylose, which is the second most abundant sugar present after glucose in lignocellulosic biomass, is important for the development of cost effective bioprocesses to fuels. Rhodococcus opacus PD630, an oleaginous bacterium, accumulates large amounts of triacylglycerols (TAGs), which can be processed into advanced liquid fuels. However, R. opacus PD630 does not metabolize xylose. RESULTS We generated DNA libraries from a Streptomyces bacterium capable of utilizing xylose and introduced them into R. opacus PD630. Xsp8, one of the engineered strains, was capable of growing on up to 180 g L-1 of xylose. Xsp8 grown in batch-cultures derived from unbleached kraft hardwood pulp hydrolysate containing 70 g L-1 total sugars was able to completely and simultaneously utilize xylose and glucose present in the lignocellulosic feedstock, and yielded 11.0 g L-1 of TAGs as fatty acids, corresponding to 45.8% of the cell dry weight. The yield of total fatty acids per gram of sugars consumed was 0.178 g, which consisted primarily of palmitic acid and oleic acid. The engineered strain Xsp8 was introduced with two heterologous genes from Streptomyces: xylA, encoding xylose isomerase, and xylB, encoding xylulokinase. We further demonstrated that in addition to the introduction and the concomitant expression of heterologous xylA and xylB genes, there is another molecular target in the R. opacus genome which fully enables the functionality of xylA and xylB genes to generate the robust xylose-fermenting strain capable of efficiently producing TAGs at high xylose concentrations. CONCLUSION We successfully engineered a R. opacus strain that is capable of completely utilizing high concentrations of xylose or mixed xylose/glucose simultaneously, and substantiated its suitability for TAG production. This study demonstrates that the engineered strain possesses a key trait of converters for lipid-based fuels production from lignocellulosic biomass.
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Affiliation(s)
- Kazuhiko Kurosawa
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Sandra J Wewetzer
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
- Present address: Department of Biochemical Engineering, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Anthony J Sinskey
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
- Engineering Systems Division, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
- Health Sciences Technology Division, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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Lipid storage in high-altitude Andean Lakes extremophiles and its mobilization under stress conditions in Rhodococcus sp. A5, a UV-resistant actinobacterium. Extremophiles 2013; 17:217-27. [PMID: 23283521 DOI: 10.1007/s00792-012-0508-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 12/17/2012] [Indexed: 10/27/2022]
Abstract
The production of triacylglycerols (TAG) or wax esters (WS) seems to be a widespread feature among extremophile bacteria living in high-altitude Andean Lakes (HAAL), Argentina. Twelve out of twenty bacterial strains isolated from HAAL were able to produce TAG or WS (between 2 and 17 % of cellular dry weight) under nitrogen-limiting culture conditions. Among these strains, the extremophile Rhodococcus sp. A5 accumulated significant amounts of TAG during growth on glucose (17 %, CDW) and hexadecane (32 %, CDW) as sole carbon sources. The role of accumulated TAG in the response to carbon starvation, osmotic stress, UV-radiation and desiccation was investigated in Rhodococcus sp. A5 using an inhibitor of TAG degradation. Cells degraded TAG during these stresses in the absence of the inhibitor. The inhibition of TAG mobilization affected cell survival during osmotic stress only during the initial growth stage. Little or no surviving cells were observed after carbon starvation, UV-treatment and desiccation, when TAG mobilization was inhibited. These results suggested that TAG metabolism is relevant for the adaptation and survival of A5 cells under carbon starvation, osmotic stress and UV irradiation, and essential under desiccation conditions, which prevail in HAAL environments.
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Hernández MA, Arabolaza A, Rodríguez E, Gramajo H, Alvarez HM. The atf2 gene is involved in triacylglycerol biosynthesis and accumulation in the oleaginous Rhodococcus opacus PD630. Appl Microbiol Biotechnol 2012; 97:2119-30. [DOI: 10.1007/s00253-012-4360-1] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 08/07/2012] [Accepted: 08/09/2012] [Indexed: 10/28/2022]
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