51
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Zhang H, Feng Y, Cui Q, Song X. Expression of Vitreoscilla hemoglobin enhances production of arachidonic acid and lipids in Mortierella alpina. BMC Biotechnol 2017; 17:68. [PMID: 28854910 PMCID: PMC5577678 DOI: 10.1186/s12896-017-0388-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 08/08/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Arachidonic acid (ARA, C20:4, n-6), which belongs to the omega-6 series of polyunsaturated fatty acids and has a variety of biological activities, is commercially produced in Mortierella alpina. Dissolved oxygen or oxygen utilization efficiency is a critical factor for Mortierella alpina growth and arachidonic acid production in large-scale fermentation. Overexpression of the Vitreoscilla hemoglobin gene is thought to significantly increase the oxygen utilization efficiency of the cells. RESULTS An optimized Vitreoscilla hemoglobin (VHb) gene was introduced into Mortierella alpina via Agrobacterium tumefaciens-mediated transformation. Compared with the parent strain, the VHb-expressing strain, termed VHb-20, grew faster under both limiting and non-limiting oxygen conditions and exhibited dramatic changes in cell morphology. Furthermore, VHb-20 produced 4- and 8-fold higher total lipid and ARA yields than those of the wild-type strain under a microaerobic environment. Furthermore, ARA production of VHb-20 was also 1.6-fold higher than that of the wild type under normal conditions. The results demonstrated that DO utilization was significantly increased by expressing the VHb gene in Mortierella alpina. CONCLUSIONS The expression of VHb enhances ARA and lipid production under both lower and normal dissolved oxygen conditions. This study provides a novel strategy and an engineered strain for the cost-efficient production of ARA.
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Affiliation(s)
- Huidan Zhang
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No.189 Songling Road, Laoshan District, Qingdao, Shandong Province 266101 China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao, Shandong 266101 China
- University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Yingang Feng
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No.189 Songling Road, Laoshan District, Qingdao, Shandong Province 266101 China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao, Shandong 266101 China
| | - Qiu Cui
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No.189 Songling Road, Laoshan District, Qingdao, Shandong Province 266101 China
- Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, Shandong 266101 China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao, Shandong 266101 China
| | - Xiaojin Song
- Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, No.189 Songling Road, Laoshan District, Qingdao, Shandong Province 266101 China
- Qingdao Engineering Laboratory of Single Cell Oil, Qingdao, Shandong 266101 China
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52
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Complete Genome Sequence of Vitreoscilla filiformis (ATCC 15551), Used as a Cosmetic Ingredient. GENOME ANNOUNCEMENTS 2017; 5:5/34/e00913-17. [PMID: 28839041 PMCID: PMC5571427 DOI: 10.1128/genomea.00913-17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report the first complete genome sequence of a Vitreoscilla filiformis strain (ATCC 15551) that is used in the cosmetic industry as Vitreoscilla ferment. The assembled genome consisted of one chromosome and two plasmids. These data will provide valuable information and important insights into the physiology of this filamentous organism.
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53
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Combinatorial metabolic engineering of Pseudomonas putida KT2440 for efficient mineralization of 1,2,3-trichloropropane. Sci Rep 2017; 7:7064. [PMID: 28765600 PMCID: PMC5539299 DOI: 10.1038/s41598-017-07435-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/23/2017] [Indexed: 01/03/2023] Open
Abstract
An industrial waste, 1,2,3-trichloropropane (TCP), is toxic and extremely recalcitrant to biodegradation. To date, no natural TCP degraders able to mineralize TCP aerobically have been isolated. In this work, we engineered a biosafety Pseudomonas putida strain KT2440 for aerobic mineralization of TCP by implantation of a synthetic biodegradation pathway into the chromosome and further improved TCP mineralization using combinatorial engineering strategies. Initially, a synthetic pathway composed of haloalkane dehalogenase, haloalcohol dehalogenase and epoxide hydrolase was functionally assembled for the conversion of TCP into glycerol in P. putida KT2440. Then, the growth lag-phase of using glycerol as a growth precursor was eliminated by deleting the glpR gene, significantly enhancing the flux of carbon through the pathway. Subsequently, we improved the oxygen sequestering capacity of this strain through the heterologous expression of Vitreoscilla hemoglobin, which makes this strain able to mineralize TCP under oxygen-limited conditions. Lastly, we further improved intracellular energy charge (ATP/ADP ratio) and reducing power (NADPH/NADP+ ratio) by deleting flagella-related genes in the genome of P. putida KT2440. The resulting strain (named KTU-TGVF) could efficiently utilize TCP as the sole source of carbon for growth. Degradation studies in a bioreactor highlight the value of this engineered strain for TCP bioremediation.
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54
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Sar T, Stark BC, Yesilcimen Akbas M. Effective ethanol production from whey powder through immobilized E. coli expressing Vitreoscilla hemoglobin. Bioengineered 2017; 8:171-181. [PMID: 27579556 PMCID: PMC5398575 DOI: 10.1080/21655979.2016.1218581] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 07/23/2016] [Accepted: 07/26/2016] [Indexed: 10/21/2022] Open
Abstract
Ethanol production from whey powder was investigated by using free as well as alginate immobilized E. coli and E. coli expressing Vitreoscilla hemoglobin (VHb) in both shake flask and fermenter cultures. Media with varying levels of whey (lactose contents of 3%, 5%, 8% or 15%) and yeast extract (0.3% or 0.5%) were evaluated with fermentation times of 48-96 h. Immobilization and VHb expression resulted in higher ethanol production with all media; the increases ranged from 2% to 89% for immobilization and from 2% to 182% for VHb expression. It was determined that growth medium containing 8% lactose with 0.5% yeast extract yielded the highest ethanol production for free or immobilized strains, with or without VHb expression, in both shake flask and fermenter cultures. Immobilization with alginate was found to be a promising process for ethanol production by VHb-expressing ethanologenic E. coli.
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Affiliation(s)
- Taner Sar
- Department of Molecular Biology and Genetics, Gebze Technical University, Gebze-Kocaeli, Turkey
| | - Benjamin C. Stark
- Biology Department, Illinois Institute of Technology, Chicago, IL, USA
| | - Meltem Yesilcimen Akbas
- Department of Molecular Biology and Genetics, Gebze Technical University, Gebze-Kocaeli, Turkey
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55
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Lara AR, Jaén KE, Sigala JC, Mühlmann M, Regestein L, Büchs J. Characterization of Endogenous and Reduced Promoters for Oxygen-Limited Processes Using Escherichia coli. ACS Synth Biol 2017; 6:344-356. [PMID: 27715021 DOI: 10.1021/acssynbio.6b00233] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Oxygen limitation can be used as a simple environmental inducer for the expression of target genes. However, there is scarce information on the characteristics of microaerobic promoters potentially useful for cell engineering and synthetic biology applications. Here, we characterized the Vitreoscilla hemoglobin promoter (Pvgb) and a set of microaerobic endogenous promoters in Escherichia coli. Oxygen-limited cultures at different maximum oxygen transfer rates were carried out. The FMN-binding fluorescent protein (FbFP), which is a nonoxygen dependent marker protein, was used as a reporter. Fluorescence and fluorescence emission rates under oxygen-limited conditions were the highest when FbFP was under transcriptional control of PadhE, Ppfl and Pvgb. The lengths of the E. coli endogenous promoters were shortened by 60%, maintaining their key regulatory elements. This resulted in improved promoter activity in most cases, particularly for PadhE, Ppfl and PnarK. Selected promoters were also evaluated using an engineered E. coli strain expressing Vitreoscilla hemoglobin (VHb). The presence of the VHb resulted in a better repression using these promoters under aerobic conditions, and increased the specific growth and fluorescence emission rates under oxygen-limited conditions. These results are useful for the selection of promoters for specific applications and for the design of modified artificial promoters.
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Affiliation(s)
- Alvaro R. Lara
- Departamento
de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa. Av. Vasco de Quiroga 4871, Santa
Fe, C.P. 05348, Mexico City, México
| | - Karim E. Jaén
- Departamento
de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa. Av. Vasco de Quiroga 4871, Santa
Fe, C.P. 05348, Mexico City, México
| | - Juan-Carlos Sigala
- Departamento
de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa. Av. Vasco de Quiroga 4871, Santa
Fe, C.P. 05348, Mexico City, México
| | - Martina Mühlmann
- RWTH Aachen University, AVT - Biochemical Engineering, Worringer Weg 1, 52074 Aachen, Germany
| | - Lars Regestein
- RWTH Aachen University, AVT - Biochemical Engineering, Worringer Weg 1, 52074 Aachen, Germany
| | - Jochen Büchs
- RWTH Aachen University, AVT - Biochemical Engineering, Worringer Weg 1, 52074 Aachen, Germany
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56
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Chen Y, Zhou H, Wang M, Tan T. Control of ATP concentration in Escherichia coli using an ATP-sensing riboswitch for enhanced S-adenosylmethionine production. RSC Adv 2017. [DOI: 10.1039/c7ra02538f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We proposed an ATP-sensing riboswitch-based strategy which could be applied to regulate the intracellular ATP concentration dynamically inE. coli. This strategy will be most beneficial for enhancing the production of the ATP-driven metabolites.
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Affiliation(s)
- Yawei Chen
- College of Chemical and Pharmaceutical Engineering
- Henan University of Science and Technology
- Luoyang 471023
- PR China
| | - Huiyun Zhou
- College of Chemical and Pharmaceutical Engineering
- Henan University of Science and Technology
- Luoyang 471023
- PR China
| | - Meng Wang
- National Energy R&D Center for Biorefinery
- College of Life Science and Technology
- Beijing University of Chemical Technology
- Beijing 100029
- PR China
| | - Tianwei Tan
- National Energy R&D Center for Biorefinery
- College of Life Science and Technology
- Beijing University of Chemical Technology
- Beijing 100029
- PR China
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57
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Enhancement of welan gum production in Sphingomonas sp. HT-1 via heterologous expression of Vitreoscilla hemoglobin gene. Carbohydr Polym 2017; 156:135-142. [DOI: 10.1016/j.carbpol.2016.08.081] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 08/24/2016] [Accepted: 08/25/2016] [Indexed: 11/24/2022]
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58
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Juárez M, González-De la Rosa CH, Memún E, Sigala JC, Lara AR. Aerobic expression of Vitreoscilla hemoglobin improves the growth performance of CHO-K1 cells. Biotechnol J 2016; 12. [PMID: 27906496 DOI: 10.1002/biot.201600438] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 11/16/2016] [Accepted: 11/29/2016] [Indexed: 11/10/2022]
Abstract
Inefficient carbon metabolism is a relevant issue during the culture of mammalian cells for the production of biopharmaceuticals. Therefore, cell engineering strategies to improve the metabolic and growth performance of cell lines are needed. The expression of Vitreoscilla stercoraria hemoglobin (VHb) has been shown to significantly reduce overflow metabolism and improve the aerobic growth of bacteria. However, the effects of VHb on mammalian cells have been rarely studied. Here, the impact of VHb on growth and lactate accumulation during CHO-K1 cell culture was investigated. For this purpose, CHO-K1 cells were transfected with plasmids carrying the vgb or gfp gene to express VHb or green fluorescence protein (GFP), respectively. VHb expression increased the specific growth rate and biomass yields on glucose and glutamine by 60 %, and reduced the amount of lactate produced per cell by 40 %, compared to the GFP-expression controls. Immunofluorescence microscopy showed that VHb is distributed in the cytoplasm and organelles, which support the hypothesis that VHb could serve as an oxygen carrier, enhancing aerobic respiration. These results are useful for the development of better producing cell lines for industrial applications.
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Affiliation(s)
- Mariana Juárez
- Posgrado en Ciencias Naturales e Ingeniería, Universidad Autónoma Metropolitana-Cuajimalpa, Ciudad de México, México
| | | | - Elisa Memún
- Departamento de Ciencias Naturales, Universidad Autónoma Metropolitana-Cuajimalpa, Ciudad de México, México
| | - Juan-Carlos Sigala
- Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Ciudad de México, México
| | - Alvaro R Lara
- Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Ciudad de México, México
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59
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Akbas MY, Stark BC. Recent trends in bioethanol production from food processing byproducts. J Ind Microbiol Biotechnol 2016; 43:1593-1609. [PMID: 27565674 DOI: 10.1007/s10295-016-1821-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 07/30/2016] [Indexed: 12/19/2022]
Abstract
The widespread use of corn starch and sugarcane as sources of sugar for the production of ethanol via fermentation may negatively impact the use of farmland for production of food. Thus, alternative sources of fermentable sugars, particularly from lignocellulosic sources, have been extensively investigated. Another source of fermentable sugars with substantial potential for ethanol production is the waste from the food growing and processing industry. Reviewed here is the use of waste from potato processing, molasses from processing of sugar beets into sugar, whey from cheese production, byproducts of rice and coffee bean processing, and other food processing wastes as sugar sources for fermentation to ethanol. Specific topics discussed include the organisms used for fermentation, strategies, such as co-culturing and cell immobilization, used to improve the fermentation process, and the use of genetic engineering to improve the performance of ethanol producing fermenters.
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Affiliation(s)
- Meltem Yesilcimen Akbas
- Department of Molecular Biology and Genetics, Gebze Technical University, Gebze-Kocaeli, Kocaeli, 41400, Turkey. .,Institute of Biotechnology, Gebze Technical University, Gebze-Kocaeli, Kocaeli, 41400, Turkey.
| | - Benjamin C Stark
- Biology Department, Illinois Institute of Technology, Chicago, IL, 60616, USA
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60
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Li HJ, He YL, Zhang DH, Yue TH, Jiang LX, Li N, Xu JW. Enhancement of ganoderic acid production by constitutively expressing Vitreoscilla hemoglobin gene in Ganoderma lucidum. J Biotechnol 2016; 227:35-40. [DOI: 10.1016/j.jbiotec.2016.04.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Revised: 04/05/2016] [Accepted: 04/08/2016] [Indexed: 11/26/2022]
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61
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Pablos TE, Olivares R, Sigala JC, Ramírez OT, Lara AR. Toward efficient microaerobic processes using engineeredEscherichia coliW3110 strains. Eng Life Sci 2016. [DOI: 10.1002/elsc.201500129] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Tania E. Pablos
- Doctorado en Ciencias Biológicas y de la Salud; Universidad Autónoma Metropolitana; México D.F. México
| | - Roberto Olivares
- Departamento de Procesos y Tecnología; Universidad Autónoma Metropolitana-Cuajimalpa; México D.F. México
| | - Juan Carlos Sigala
- Departamento de Procesos y Tecnología; Universidad Autónoma Metropolitana-Cuajimalpa; México D.F. México
| | - Octavio T. Ramírez
- Departamento de Medicina Molecular y Bioprocesos; Instituto de Biotecnología; Universidad Nacional Autónoma de México; Cuernavaca México
| | - Alvaro R. Lara
- Departamento de Procesos y Tecnología; Universidad Autónoma Metropolitana-Cuajimalpa; México D.F. México
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62
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Gu Y, Wang X, Yang C, Geng W, Feng J, Wang Y, Wang S, Song C. Effects of Chromosomal Integration of the Vitreoscilla Hemoglobin Gene (vgb) and S-Adenosylmethionine Synthetase Gene (metK) on ε-Poly-l-Lysine Synthesis in Streptomyces albulus NK660. Appl Biochem Biotechnol 2016; 178:1445-57. [DOI: 10.1007/s12010-015-1958-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 12/14/2015] [Indexed: 10/22/2022]
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63
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Li HJ, Zhang DH, Yue TH, Jiang LX, Yu X, Zhao P, Li T, Xu JW. Improved polysaccharide production in a submerged culture of Ganoderma lucidum by the heterologous expression of Vitreoscilla hemoglobin gene. J Biotechnol 2016; 217:132-7. [DOI: 10.1016/j.jbiotec.2015.11.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 10/30/2015] [Accepted: 11/13/2015] [Indexed: 11/30/2022]
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64
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Kunkel SA, Pagilla KR, Stark BC. Engineering of Nitrosomonas europaea to express Vitreoscilla hemoglobin enhances oxygen uptake and conversion of ammonia to nitrite. AMB Express 2015; 5:135. [PMID: 26231847 PMCID: PMC4522006 DOI: 10.1186/s13568-015-0135-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 07/23/2015] [Indexed: 11/29/2022] Open
Abstract
Nitrosomonas europaea was transformed with a recombinant plasmid bearing the gene (vgb) encoding the hemoglobin (VHb) from the bacterium Vitreoscilla under control of the N. europaea amoC P1 promoter. Vgb was maintained stably and appeared to be expressed in the transformants at VHb levels of about 0.75 nmol/g wet weight. Expression of VHb in the N. europaea transformants was correlated with an approximately 2 fold increase in oxygen uptake rate by whole cells at oxygen concentrations in the range of 75-100% saturation, but no change in oxygen uptake rate at oxygen concentrations below 25% saturation. VHb expression was also correlated with an increase of as much as about 30% in conversion of ammonia to nitrite by growing cells. The results suggest that engineering of key aerobic wastewater bacteria to express bacterial hemoglobins may be a useful strategy to produce species with enhanced respiratory abilities.
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Affiliation(s)
- Stephanie A Kunkel
- />Department of Biology, Illinois Institute of Technology, Chicago, IL 60616 USA
- />Department of Civil, Architectural and Environmental Engineering, Illinois Institute of Technology, Chicago, IL 60616 USA
| | - Krishna R Pagilla
- />Department of Civil, Architectural and Environmental Engineering, Illinois Institute of Technology, Chicago, IL 60616 USA
| | - Benjamin C Stark
- />Department of Biology, Illinois Institute of Technology, Chicago, IL 60616 USA
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65
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Dobler L, Vilela LF, Almeida RV, Neves BC. Rhamnolipids in perspective: gene regulatory pathways, metabolic engineering, production and technological forecasting. N Biotechnol 2015; 33:123-35. [PMID: 26409933 DOI: 10.1016/j.nbt.2015.09.005] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 08/28/2015] [Accepted: 09/17/2015] [Indexed: 10/23/2022]
Abstract
Rhamnolipids have emerged as a very promising class of biosurfactants in the last decades, exhibiting properties of great interest in several industrial applications, and have represented a suitable alternative to chemically-synthesized surfactants. This class of biosurfactants has been extensively studied in recent years, aiming at their large-scale production based on renewable resources, which still require high financial costs. Development of non-pathogenic, high-producing strains has been the focus of a number of studies involving heterologous microbial hosts as platforms. However, the intricate gene regulation network controlling rhamnolipid biosynthesis represents a challenge to metabolic engineering and remains to be further understood and explored. This article provides an overview of the biosynthetic pathways and the main gene regulatory factors involved in rhamnolipid production within Pseudomonas aeruginosa, the prototypal producing species. In addition, we provide a perspective view into the main strategies applied to metabolic engineering and biotechnological production.
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Affiliation(s)
- Leticia Dobler
- Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Leonardo F Vilela
- Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Rodrigo V Almeida
- Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Bianca C Neves
- Department of Biochemistry, Institute of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
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66
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Kunkel SA, Pagilla KR, Stark BC. Directed evolution to produce sludge communities with improved oxygen uptake abilities. Appl Microbiol Biotechnol 2015; 99:10725-34. [PMID: 26278534 DOI: 10.1007/s00253-015-6891-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/23/2015] [Accepted: 07/28/2015] [Indexed: 11/30/2022]
Abstract
Two activated sludge cultures, seeded with activated sludge from the same source, were cultivated for 370 days in synthetic wastewater. Both cultures were transferred weekly to fresh medium; one culture was operated at high dissolved oxygen (DO) (near saturation) and the other at low DO (0.25 mg O2/L). There were significant changes in the abundances of bacterial species and phyla present in each culture throughout the 370-day operational period. In the low DO culture, over time, there was a continuously increasing proportion of cells of species known to encode truncated hemoglobins (Hbs). These are the types of Hbs which may enhance delivery of oxygen to the respiratory chain, to enhance ATP production, especially under low aeration conditions. The levels of heme b, the heme found in Vitreoscilla hemoglobin, increased in parallel to the increase in Hb-encoding species, to much higher levels in the low DO culture than in the high DO culture. Specific oxygen uptake rates increased by 3 % for the high DO culture near the end of the 370-day period, while those for the low DO culture increased steadily to a level 28 % higher than that of the starting culture. Thus, imposition of low DO conditions may, due to selection for Hb-expressing species, be useful in developing bacterial communities with enhanced ability to function efficiently in aerobic wastewater treatment, especially under low aeration conditions.
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Affiliation(s)
- Stephanie A Kunkel
- Department of Biology, Illinois Institute of Technology, Chicago, IL, 60616, USA
| | - Krishna R Pagilla
- Department of Civil, Architectural and Environmental Engineering, Illinois Institute of Technology, Chicago, IL, 60616, USA
| | - Benjamin C Stark
- Department of Biology, Illinois Institute of Technology, Chicago, IL, 60616, USA.
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67
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Mora-Lugo R, Madrigal M, Yelemane V, Fernandez-Lahore M. Improved biomass and protein production in solid-state cultures of an Aspergillus sojae strain harboring the Vitreoscilla hemoglobin. Appl Microbiol Biotechnol 2015. [PMID: 26224427 PMCID: PMC4628083 DOI: 10.1007/s00253-015-6851-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The biotechnological value of Aspergillus sojae ATCC 20235 (A. sojae) for production of pectinases in solid-state fermentation (SSF) has been demonstrated recently. However, a common drawback of fungal solid-state cultures is the poor diffusion of oxygen into the fungi that limits its growth and biological productivity. The bacterial Vitreoscilla hemoglobin (VHb) has favored the metabolism and productivities of various bacterial and yeast strains besides alleviating hypoxic conditions of its native host, but the use of VHb in filamentous fungi still remains poor explored. Based on the known effects of VHb, this study assessed its applicability to improve A. sojae performance in SSF. The VHb gene (vgb) under control of the constitutive Aspergillus nidulants gpdA promoter was introduced into the genome of A. sojae by Agrobacterium-mediated transformation. Successful fungal transformants were identified by fluorescence microscopy and polymerase chain reaction (PCR) analyses. In solid-state cultures, the content of protease, exo-polygalacturonase (exo-PG), and exo-polymethylgalacturonase (exo-PMG) of the transformed fungus (A. sojae vgb+) improved were 26, 60, and 44 % higher, respectively, in comparison to its parental strain (A. sojae wt). Similarly, biomass content was also 1.3 times higher in the transformant strain. No significant difference was observed in endo-polygalacturonase (endo-PG) content between both fungal strains, suggesting dissimilar effects of VHb towards different enzymatic productions. Overall, our results show that biomass, protease, and exo-pectinase content of A. sojae in SSF can be improved by transformation with VHb.
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Affiliation(s)
- Rodrigo Mora-Lugo
- Downstream Bioprocessing Lab, Jacobs University Bremen gGmbH, Bremen, Germany.
| | - Marvin Madrigal
- Downstream Bioprocessing Lab, Jacobs University Bremen gGmbH, Bremen, Germany. .,Instituto Clodomiro Picado and Departamento de Bioquímica, Universidad de Costa Rica, San José, Costa Rica.
| | - Vikas Yelemane
- Downstream Bioprocessing Lab, Jacobs University Bremen gGmbH, Bremen, Germany.
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68
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Wang Y, Zhang Y, Jiang T, Meng J, Sheng B, Yang C, Gao C, Xu P, Ma C. A novel biocatalyst for efficient production of 2-oxo-carboxylates using glycerol as the cost-effective carbon source. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:186. [PMID: 26609321 PMCID: PMC4659176 DOI: 10.1186/s13068-015-0368-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 10/28/2015] [Indexed: 05/02/2023]
Abstract
BACKGROUND The surplus of glycerol has increased remarkably as a main byproduct during the biofuel's production. Exploiting an alternative route for glycerol utilization is significantly important for sustainability of biofuels. RESULTS A novel biocatalyst that could be prepared from glycerol for producing 2-oxo-carboxylates was developed. First, Pseudomonas putida KT2440 was reconstructed by deleting lldR to develop a mutant expressing the NAD-independent lactate dehydrogenases (iLDHs) constitutively. Then, the Vitreoscilla hemoglobin (VHb) was heterologously expressed to further improve the biotransformation activity. The reconstructed strain, P. putida KT2440 (ΔlldR)/pBSPPcGm-vgb, exhibited high activities of iLDHs when cultured with glycerol as the carbon source. This cost-effective biocatalyst could efficiently produce pyruvate and 2-oxobutyrate from dl-lactate and dl-2-hydroxybutyrate with high molar conversion rates of 91.9 and 99.8 %, respectively. CONCLUSIONS The process would not only be a promising alternative for the production of 2-oxo-carboxylates, but also be an example for preparation of efficient biocatalysts for the value-added utilization of glycerol.
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Affiliation(s)
- Yujiao Wang
- />State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 People’s Republic of China
| | - Yingxin Zhang
- />State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 People’s Republic of China
| | - Tianyi Jiang
- />State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 People’s Republic of China
| | - Jingjing Meng
- />State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 People’s Republic of China
| | - Binbin Sheng
- />State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 People’s Republic of China
| | - Chunyu Yang
- />State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 People’s Republic of China
| | - Chao Gao
- />State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 People’s Republic of China
| | - Ping Xu
- />State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 People’s Republic of China
- />State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240 People’s Republic of China
| | - Cuiqing Ma
- />State Key Laboratory of Microbial Technology, Shandong University, Jinan, 250100 People’s Republic of China
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