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Biermann R, Beutel S. Endospore production of Bacillus spp. for industrial use. Eng Life Sci 2023; 23:e2300013. [PMID: 37970521 PMCID: PMC10630785 DOI: 10.1002/elsc.202300013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 08/02/2023] [Accepted: 10/05/2023] [Indexed: 11/17/2023] Open
Abstract
The increased occurrence of antibiotic resistance and the harmful use of pesticides are a major problem of modern times. A ban on the use of antibiotics as growth promoters in animal breeding has put a focus on the probiotics market. Probiotic food supplements are versatile and show promising results in animal and human nutrition. Chemical pesticides can be substituted by biopesticides, which are very effective against various pests in plants due to increased research. What these fields have in common is the use of spore-forming bacteria. The endospore-forming Bacillus spp. belonging to this group offer an effective solution to the aforementioned problems. Therefore, the biotechnological production of sufficient qualities of such endospores has become an innovative and financially viable field of research. In this review, the production of different Bacillus spp. endospores will be reviewed. For this purpose, the media compositions, cultivation conditions and bioprocess optimization methods of the last 20 years are presented and reflected.
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Affiliation(s)
- Riekje Biermann
- Institute of Technical ChemistryLeibniz University HannoverHannoverGermany
| | - Sascha Beutel
- Institute of Technical ChemistryLeibniz University HannoverHannoverGermany
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2
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Vlajkov V, Pajčin I, Loc M, Budakov D, Dodić J, Grahovac M, Grahovac J. The Effect of Cultivation Conditions on Antifungal and Maize Seed Germination Activity of Bacillus-Based Biocontrol Agent. BIOENGINEERING (BASEL, SWITZERLAND) 2022; 9:bioengineering9120797. [PMID: 36551004 PMCID: PMC9774550 DOI: 10.3390/bioengineering9120797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 11/28/2022] [Accepted: 12/06/2022] [Indexed: 12/15/2022]
Abstract
Aflatoxin contamination is a global risk and a concerning problem threatening food safety. The biotechnological answer lies in the production of biocontrol agents that are effective against aflatoxins producers. In addition to their biocontrol effect, microbial-based products are recognized as efficient biosolutions for plant nutrition and growth promotion. The present study addresses the characterization of the representative of Phaseolus vulgaris rhizosphere microbiome, Bacillus sp. BioSol021, regarding plant growth promotion traits, including the activity of protease, cellulase, xylanase, and pectinase with the enzymatic activity index values 1.06, 2.04, 2.41, and 3.51, respectively. The potential for the wider commercialization of this kind of product is determined by the possibility of developing a scalable bioprocess solution suitable for technology transfer to an industrial scale. Therefore, the study addresses one of the most challenging steps in bioprocess development, including the production scale-up from the Erlenmeyer flask to the laboratory bioreactor. The results indicated the influence of the key bioprocess parameters on the dual mechanism of action of biocontrol effects against the aflatoxigenic Aspergillus flavus, as well on maize seed germination activity, pointing out the positive impact of high aeration intensity and agitation rate, resulting in inhibition zone diameters of 60 mm, a root length 96 mm, and a shoot length 27 mm.
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Affiliation(s)
- Vanja Vlajkov
- Faculty of Technology Novi Sad, University of Novi Sad, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia
- Correspondence: (V.V.); (J.G.)
| | - Ivana Pajčin
- Faculty of Technology Novi Sad, University of Novi Sad, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia
| | - Marta Loc
- Faculty of Agriculture, University of Novi Sad, Trg Dositeja Obradovića 8, 21000 Novi Sad, Serbia
| | - Dragana Budakov
- Faculty of Agriculture, University of Novi Sad, Trg Dositeja Obradovića 8, 21000 Novi Sad, Serbia
| | - Jelena Dodić
- Faculty of Technology Novi Sad, University of Novi Sad, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia
| | - Mila Grahovac
- Faculty of Agriculture, University of Novi Sad, Trg Dositeja Obradovića 8, 21000 Novi Sad, Serbia
| | - Jovana Grahovac
- Faculty of Technology Novi Sad, University of Novi Sad, Bulevar cara Lazara 1, 21000 Novi Sad, Serbia
- Correspondence: (V.V.); (J.G.)
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Zhang J, Luo X, Pang X, Li X, Lu Y, Sun J. Promoted Spore Formation of Bacillus amyloliquefaciens fmbJ by its Secondary Metabolite Bacillomycin D Coordinated with Mn 2. Indian J Microbiol 2022; 62:531-539. [PMID: 36458223 PMCID: PMC9705635 DOI: 10.1007/s12088-022-01026-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 05/08/2022] [Indexed: 11/05/2022] Open
Abstract
In Bacillus, the spore formation process is associated with the synthesis and release of secondary metabolites. A large number of studies have been conducted to systematically elucidate the pathways and mechanisms of spore formation. However, there are no studies have explored the relationship between secondary metabolites and spores. In this study, we investigated the relationship between its secondary metabolite bacillomycin D (BD) and spores using the simpler dipicolonic acid fluorimetry assay for spore counting in Bacillus amyloliquefaciens fmbJ. Our results showed that BD could promote the spore formation of B. amyloliquefaciens fmbJ and had a synergistic effect with certain concentrations of Mn2+. When 15.6 mg/L of BD and 1 mM of Mn2+ were added, the number of fmbJ spores increased from 1.42 × 108 CFU/mL to 2.02 × 108 CFU/mL after 36 h of incubation. The expressions of spore formation (kinA, kinB, kinC, kinD, kinE and spo0A) and Mn-related genes (mntA, mntH, mneS, mneP) were studied by RT-PCR. The results indicated that BD and Mn2+ promoted the spore formation of fmbJ by stimulating the transcription of kinB, kinD and increasing the influence of spo0F-spo0A phosphorylation transmission. This study provided a new idea to improve the spore production of B. amyloliquefaciens and laid the foundation for its industrial production. Supplementary Information The online version contains supplementary material available at 10.1007/s12088-022-01026-9.
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Affiliation(s)
- Jin Zhang
- College of Food Science and Engineering/Collaborative, Innovation Center for Modern Grain Circulation and Safety/Key Laboratory of Grains and Oils Quality Control and Processing, Nanjing University of Finance and Economics, 3 Wenyuan Road, Xianlin University Town, Nanjing, 210023 Jiangsu Province People’s Republic of China
| | - Xiaojiao Luo
- College of Food Science and Engineering/Collaborative, Innovation Center for Modern Grain Circulation and Safety/Key Laboratory of Grains and Oils Quality Control and Processing, Nanjing University of Finance and Economics, 3 Wenyuan Road, Xianlin University Town, Nanjing, 210023 Jiangsu Province People’s Republic of China
| | - Xinyi Pang
- College of Food Science and Engineering/Collaborative, Innovation Center for Modern Grain Circulation and Safety/Key Laboratory of Grains and Oils Quality Control and Processing, Nanjing University of Finance and Economics, 3 Wenyuan Road, Xianlin University Town, Nanjing, 210023 Jiangsu Province People’s Republic of China
| | - Xiangfei Li
- College of Food Science and Engineering/Collaborative, Innovation Center for Modern Grain Circulation and Safety/Key Laboratory of Grains and Oils Quality Control and Processing, Nanjing University of Finance and Economics, 3 Wenyuan Road, Xianlin University Town, Nanjing, 210023 Jiangsu Province People’s Republic of China
| | - Yingjian Lu
- College of Food Science and Engineering/Collaborative, Innovation Center for Modern Grain Circulation and Safety/Key Laboratory of Grains and Oils Quality Control and Processing, Nanjing University of Finance and Economics, 3 Wenyuan Road, Xianlin University Town, Nanjing, 210023 Jiangsu Province People’s Republic of China
| | - Jing Sun
- College of Food Science and Engineering/Collaborative, Innovation Center for Modern Grain Circulation and Safety/Key Laboratory of Grains and Oils Quality Control and Processing, Nanjing University of Finance and Economics, 3 Wenyuan Road, Xianlin University Town, Nanjing, 210023 Jiangsu Province People’s Republic of China
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Optimization of Growth Conditions for the Production of Bacillus subtilis Using Central Composite Design and Its Antagonism Against Pathogenic Fungi. Probiotics Antimicrob Proteins 2022; 15:682-693. [PMID: 35006575 DOI: 10.1007/s12602-021-09904-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/28/2021] [Indexed: 10/19/2022]
Abstract
Today, the enhancement of spore yields of Bacillus subtilis has considerable interest and has been widely investigated. In this context, studies have been carried out to improve the spore yield as well as the production amount. In order to perform this, optimization studies are conducted for large-scale production of B. subtilis in bioreactors. The prokaryotic structure, high extracellular production potential, lack of pathogenic activity, well-known fermentation technology and short fermentation time are the prominent advantages for the production of B. subtilis in a bioreactor. The Bacillus species produce a wide variety of antifungal and antimicrobial compounds, making them ideal biological control agents. In this study, first, the growth conditions of the medium were investigated and then optimized using the central composite design approach to achieve the highest productivity for the growth of B. subtilis. In the experiments, the effect of temperature of 25, 30 and 35 °C and pH level of 6.0, 7.0 and 8.0 on spore yield was studied. Moreover, the antifungal activity of the B. subtilis culture was investigated against pathogenic fungi: Colletotrichum gloeosporioides, Botrytis cinerea and Aspergillus brasiliensis.
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On-line monitoring of industrial interest Bacillus fermentations, using impedance spectroscopy. J Biotechnol 2022; 343:52-61. [PMID: 34826536 DOI: 10.1016/j.jbiotec.2021.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 10/12/2021] [Accepted: 11/13/2021] [Indexed: 11/21/2022]
Abstract
Impedance spectroscopy is a technique used to characterize electrochemical systems, increasing its applicability as well to monitor cell cultures. During their growth, Bacillus species have different phases which involve the production and consumption of different metabolites, culminating in the cell differentiation process that allows the generation of bacterial spores. In order to use impedance spectroscopy as a tool to monitor industrial interest Bacillus cultures, we conducted batch fermentations of Bacillus species such as B. subtilis, B. amyloliquefaciens, and B. licheniformis coupled with this technique. Each fermentation was characterized by the scanning of 50 frequencies between 0.5 and 5 MHz every 30 min. Pearson's correlation between impedance and phase angle profiles (obtained from each frequency scanned) with the kinetic profiles of each strain allowed the selection of fixed frequencies of 0.5, 1.143, and 1.878 MHz to follow-up of the fermentations of B. subtilis, B. amyloliquefaciens and B. licheniformis, respectively. Dielectric profiles of impedance, phase angle, reactance, and resistance obtained at the fixed frequency showed consistent changes with exponential, transition, and spore release phases.
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Fungal Based Biopolymer Composites for Construction Materials. MATERIALS 2021; 14:ma14112906. [PMID: 34071470 PMCID: PMC8198279 DOI: 10.3390/ma14112906] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 05/25/2021] [Accepted: 05/26/2021] [Indexed: 11/25/2022]
Abstract
Environmental contamination, extensive exploitation of fuel sources and accessibility of natural renewable resources represent the premises for the development of composite biomaterials. These materials have controlled properties, being obtained through processes operated in mild conditions with low costs, and contributing to the valorization of byproducts from agriculture and industry fields. A novel board composite including lignocelullosic substrate as wheat straws, fungal mycelium and polypropylene embedded with bacterial spores was developed and investigated in the present study. The bacterial spores embedded in polymer were found to be viable even after heat exposure, helping to increase the compatibility of polymer with hydrophilic microorganisms. Fungal based biopolymer composite was obtained after cultivation of Ganoderma lucidum macromycetes on a mixture including wheat straws and polypropylene embedded with spores from Bacillus amyloliquefaciens. Scanning electron microscopy (SEM) and light microscopy images showed the fungal mycelium covering the substrates with a dense network of filaments. The resulted biomaterial is safe, inert, renewable, natural, biodegradable and it can be molded in the desired shape. The fungal biocomposite presented similar compressive strength and improved thermal insulation capacity compared to polystyrene with high potential to be used as thermal insulation material for applications in construction sector.
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Ruiz Sella SRB, Bueno T, de Oliveira AAB, Karp SG, Soccol CR. Bacillus subtilis natto as a potential probiotic in animal nutrition. Crit Rev Biotechnol 2021; 41:355-369. [PMID: 33563053 DOI: 10.1080/07388551.2020.1858019] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The growing global demand for animal products and processed meat has created a challenge for the livestock sector to enhance animal productivity without compromising product quality. The restriction of antibiotics in animal feeds as growth promoters makes the use of probiotics a natural and safe alternative to obtain functional foods that provide animal health and quality and to maintain food safety for consumers. To incorporate these additives into the diet, detailed studies are required, in which in vitro and in vivo assays are used to prove the efficacy and to ensure the safety of probiotic candidate strains. Studies on the use of Bacillus subtilis natto as a spore-forming probiotic bacterium in animal nutrition have shown no hazardous effects and have demonstrated the effectiveness of its use as a probiotic, mainly due to its proven antimicrobial, anti-inflammatory, antioxidant, enzymatic, and immunomodulatory activity. This review summarizes the recent scientific background on the probiotic effects of B. subtilis natto in animal nutrition. It focuses on its safety assessment, host-associated efficacy, and industrial requirements.
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Affiliation(s)
- Sandra R B Ruiz Sella
- Department of Bioprocess Engineering and Biotechnology, Federal University of Paraná, Curitiba, Brazil.,Departament of Research and Development, Production and Research Centre of Immunobiological Products, Secretaria de Estado da Saúde, Piraquara, Brazil
| | - Tarcila Bueno
- Department of Bioprocess Engineering and Biotechnology, Federal University of Paraná, Curitiba, Brazil.,Biotechnology Coordination, Federal Institute of Paraná, Curitiba, Brazil
| | - Angelo A B de Oliveira
- Department of Bioprocess Engineering and Biotechnology, Federal University of Paraná, Curitiba, Brazil
| | - Susan Grace Karp
- Department of Bioprocess Engineering and Biotechnology, Federal University of Paraná, Curitiba, Brazil
| | - Carlos Ricardo Soccol
- Department of Bioprocess Engineering and Biotechnology, Federal University of Paraná, Curitiba, Brazil
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9
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Recent Advances in the Physiology of Spore Formation for Bacillus Probiotic Production. Probiotics Antimicrob Proteins 2020; 11:731-747. [PMID: 30515722 DOI: 10.1007/s12602-018-9492-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Spore-forming probiotic bacteria have received a wide and constantly increasing scientific and commercial interest. Among them, Bacillus species are the most studied and well-characterized Gram-positive bacteria. The use of bacilli as probiotic products is expanding especially rapidly due to their inherent ability to form endospores with unique survivability and tolerance to extreme environments and to produce a large number of valuable metabolites coupled with their bio-therapeutic potential demonstrating immune stimulation, antimicrobial activities and competitive exclusion. Ease of Bacillus spp. production and stability during processing and storage make them a suitable candidate for commercial manufacture of novel foods or dietary supplements for human and animal feeds for livestock, especially in the poultry and aquaculture industries. Therefore, the development of low-cost and competitive technologies for the production of spore-forming probiotic bacteria through understanding physiological peculiarities and mechanisms determining the growth and spore production by Bacillus spp. became necessary. This review summarizes the recent literature and our own data on the physiology of bacilli growth and spore production in the submerged and solid-state fermentation conditions, focusing on the common characteristics and unique properties of individual bacteria as well as on several approaches providing enhanced spore formation.
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Yan ZY, Yao CX, Wan DY, Wang LL, Du QQ, Li ZQ, Wu SM. A sensitive and simple method for detecting Cu2+ in plasma using fluorescent Bacillus amyloliquefaciens containing intracellularly biosynthesized CdSe quantum dots. Enzyme Microb Technol 2018; 119:37-44. [DOI: 10.1016/j.enzmictec.2018.08.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 08/30/2018] [Accepted: 08/31/2018] [Indexed: 02/01/2023]
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Khardziani T, Kachlishvili E, Sokhadze K, Elisashvili V, Weeks R, Chikindas ML, Chistyakov V. Elucidation of Bacillus subtilis KATMIRA 1933 Potential for Spore Production in Submerged Fermentation of Plant Raw Materials. Probiotics Antimicrob Proteins 2018; 9:435-443. [PMID: 28695539 DOI: 10.1007/s12602-017-9303-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In this study, the effects of several key factors to increase spore production by Bacillus subtilis subsp. KATMIRA 1933 were evaluated in shake flask experiments. In a synthetic medium, glucose concentration played a crucial role in the expression of bacilli sporulation capacity. In particular, maximum spore yield (2.3 × 109 spores/mL) was achieved at low glucose concentration (2 g/L), and further gradual increase of the carbon source content in the medium caused a decrease in sporulation capacity. Substitution of glucose with several inexpensive lignocellulosic materials was found to be a reasonable way to achieve high cell density and sporulation. Of the materials tested, milled mandarin peels at a concentration of 40 g/L served as the best growth substrate. In these conditions, bacilli secreted sufficient levels of glycosyl hydrolases, providing slow hydrolysis of the mandarin peel's polysaccharides to metabolizable sugars, providing the bacterial culture with an adequate carbon and energy source. Among nitrogen sources tested, peptone was found to favor spore production. Moreover, it was shown that cheese and cottage cheese whey usage, instead of distilled water, significantly increases spore formation. After optimization of the nutrient medium in the shake flask experiments, the technical feasibility of large-scale spore production by B. subtilis KATMIRA 1933 was confirmed in a laboratory fermenter. The spore yield (7 × 1010 spores/mL) obtained using a bioreactor was higher than those previously reported.
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Affiliation(s)
- Tamar Khardziani
- Agricultural University of Georgia, David Agmashenebeli alley 240, 0159, Tbilisi, Georgia
| | - Eva Kachlishvili
- Agricultural University of Georgia, David Agmashenebeli alley 240, 0159, Tbilisi, Georgia
| | - Kakha Sokhadze
- Agricultural University of Georgia, David Agmashenebeli alley 240, 0159, Tbilisi, Georgia
| | - Vladimir Elisashvili
- Agricultural University of Georgia, David Agmashenebeli alley 240, 0159, Tbilisi, Georgia.
| | - Richard Weeks
- Health Promoting Naturals Laboratory, School of Environmental and Biological Sciences, Rutgers State University, New Brunswick, NJ, USA
| | - Michael L Chikindas
- Health Promoting Naturals Laboratory, School of Environmental and Biological Sciences, Rutgers State University, New Brunswick, NJ, USA.,Center for Digestive Health, New Jersey Institute for Food, Nutrition and Health, New Brunswick, NJ, USA
| | - Vladimir Chistyakov
- D. I. Ivanovsky Academy of Biology and Biotechnology, Southern Federal University, Rostov-on-Don, Russia
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Ren H, Su YT, Guo XH. Rapid optimization of spore production from Bacillus amyloliquefaciens in submerged cultures based on dipicolinic acid fluorimetry assay. AMB Express 2018; 8:21. [PMID: 29453688 PMCID: PMC5815978 DOI: 10.1186/s13568-018-0555-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Accepted: 02/11/2018] [Indexed: 11/29/2022] Open
Abstract
Some optimization techniques have been widely applied for spore fermentation based on the plate counting. This study optimized the culture medium for the spore production of Bacillus amyloliquefaciens BS-20 and investigated the feasibility of using a dipicolonic acid (DPA) fluorimetry assay as a simpler alternative to plate counting for evaluating spore yields. Through the single-factor experiment, the metal ions and agro-industrial raw materials that significantly enhanced spore production were determined. After conducting a response surface methodology (RSM) analysis of several metal ions, the combined use of optimum concentrations of Mn2+, Fe2+, and Ca2+ in culture media produced a 3.4-fold increase in spore yields. Subsequently, supplementing soybean meal and corn meal with optimum concentrations determined by another RSM analysis produced an 8.8-fold increase. The final spore concentration from a culture medium incorporating optimum concentrations of the metal ions and raw materials mentioned above was verified to reach (8.05 ± 0.70) × 109 CFU/mL by both DPA fluorimetry and plate counting. The results suggest that the use of DPA fluorescence intensity as an alternative value to colony counting provides a general method for assessing spore yields with less work and shorter time.
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Affiliation(s)
- Hang Ren
- Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Science, South-Central University for Nationalities, No. 182, Minyuan Road, Hongshan District, Wuhan, 430074 Hubei China
| | - Ya-ting Su
- Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Science, South-Central University for Nationalities, No. 182, Minyuan Road, Hongshan District, Wuhan, 430074 Hubei China
| | - Xiao-hua Guo
- Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Science, South-Central University for Nationalities, No. 182, Minyuan Road, Hongshan District, Wuhan, 430074 Hubei China
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Shahrokh Esfahani S, Emtiazi G, Shafiei R, Ghorbani N, Zarkesh Esfahani SH. Tolerance Induction of Temperature and Starvation with Tricalcium Phosphate on Preservation and Sporulation in Bacillus amyloliquefaciens Detected by Flow Cytometry. Curr Microbiol 2016; 73:366-373. [DOI: 10.1007/s00284-016-1066-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 04/13/2016] [Indexed: 11/24/2022]
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Effect of medium components and culture conditions in Bacillus subtilis EA-CB0575 spore production. Bioprocess Biosyst Eng 2015; 38:1879-88. [PMID: 26135004 DOI: 10.1007/s00449-015-1428-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 06/12/2015] [Indexed: 10/23/2022]
Abstract
Bacillus subtilis spores have important biotechnological applications; however, achieving both, high spore cell densities and sporulation efficiencies in fermentation, is poorly reported. In this study, medium components and culture conditions were optimized with different statistical methods to increase spore production of the plant growth promoting rhizobacteria B. subtilis EA-CB0575. Key medium components were determined with Plackett-Burman (PB) design, and the optimum concentration levels of two components (glucose, MgSO4·7H2O) were optimized with a full factorial and central composite design, achieving 1.37 × 10(9) CFU/mL of spore cell density and 93.5 % of sporulation efficiency in shake flask. The optimized medium was used to determine the effect of culture conditions on spore production at bioreactor level, finding that maintaining pH control did not affect significantly spore production, while the interaction of agitation and aeration rates had a significant effect on spore cell density. The overall optimization generated a 17.2-fold increase in spore cell density (8.78 × 10(9) CFU/mL) and 1.9-fold increase in sporulation efficiency (94.2 %) compared to that of PB design. These results indicate the potential of B. subtilis EA-CB0575 to produce both, high spore cell densities and sporulation efficiencies, with very low nutrient requirements and short incubation period which can represent savings of process production.
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