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Masmoudi F, Ben Khedher S, Kamoun A, Zouari N, Tounsi S, Trigui M. Combinatorial effect of mutagenesis and medium component optimization on Bacillus amyloliquefaciens antifungal activity and efficacy in eradicating Botrytis cinerea. Microbiol Res 2017; 197:29-38. [DOI: 10.1016/j.micres.2017.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 01/02/2017] [Accepted: 01/07/2017] [Indexed: 11/25/2022]
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A promising HD133-like strain of Bacillus thuringiensis with dual efficiency to the two Lepidopteran pests: Spodoptera littoralis (Noctuidae) and Ephestia kuehniella (Pyralidae). Toxicon 2016; 118:112-20. [DOI: 10.1016/j.toxicon.2016.04.045] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 04/21/2016] [Accepted: 04/25/2016] [Indexed: 11/20/2022]
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Guan C, Cui W, Cheng J, Zhou L, Liu Z, Zhou Z. Development of an efficient autoinducible expression system by promoter engineering in Bacillus subtilis. Microb Cell Fact 2016; 15:66. [PMID: 27112779 PMCID: PMC4845504 DOI: 10.1186/s12934-016-0464-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 04/13/2016] [Indexed: 11/11/2022] Open
Abstract
Background Bacillus subtilis, a Gram-positive organism, has been developed to be an attractive expression platform to produce both secreted and cytoplasmic proteins owing to its prominent biological characteristics. We previously developed an auto-inducible expression system containing the srfA promoter (PsrfA) which was activated by the signal molecules acting in the quorum-sensing pathway for competence. The PsrfA promoter exhibited the unique property of inducer-free activity that is closely correlated with cell density. Results To improve the PsrfA-mediated expression system to the high-cell-density fermentation for industrial production in the B. subtilis mutant strain that is unable to sporulate, a spore mutant strain BSG1682 was developed, and the PsrfA promoter was enhanced by promoter engineering. Using green fluorescent protein (GFP) as the reporter, higher fluorescent intensity was observed in BSG1682 with expression from either plasmid or chromosome than that of the wild type B. subtilis 168. Thereafter, the PsrfA was engineered, yielding a library of PsrfA derivatives varied in the strength of GFP expression. The P23 promoter exhibited the best performance, almost twofold stronger than that of PsrfA. Two heterologous proteins, aminopeptidase (AP) and nattokinase (NK), were successfully overproduced under the control of P23 in BSG1682. Finally, the capacity of the expression system was demonstrated in batch fermentation in a 5-L fermenter. Conclusions The expression system demonstrates prominence in the activity of the auto-inducible promoter. Desired proteins could be highly and stably produced by integrating the corresponding genes downstream of the promoter on the plasmid or the chromosome in strain BSG1682. The expression system is conducive to the industrial production of pharmaceuticals and heterologous proteins in high-cell-density fermentation in BSG1682.
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Affiliation(s)
- Chengran Guan
- School of Biotechnology, Key Laboratory of Industrial Biotechnology (Ministry of Education), Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China
| | - Wenjing Cui
- School of Biotechnology, Key Laboratory of Industrial Biotechnology (Ministry of Education), Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China.
| | - Jintao Cheng
- School of Biotechnology, Key Laboratory of Industrial Biotechnology (Ministry of Education), Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China
| | - Li Zhou
- School of Biotechnology, Key Laboratory of Industrial Biotechnology (Ministry of Education), Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China
| | - Zhongmei Liu
- School of Biotechnology, Key Laboratory of Industrial Biotechnology (Ministry of Education), Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China
| | - Zhemin Zhou
- School of Biotechnology, Key Laboratory of Industrial Biotechnology (Ministry of Education), Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, Jiangsu, China.
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Ben Khedher S, Jaoua S, Zouari N. Overcome of Carbon Catabolite Repression of Bioinsecticides Production by Sporeless Bacillus thuringiensis through Adequate Fermentation Technology. BIOTECHNOLOGY RESEARCH INTERNATIONAL 2014; 2014:698587. [PMID: 25309756 PMCID: PMC4182890 DOI: 10.1155/2014/698587] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 07/03/2014] [Accepted: 09/03/2014] [Indexed: 11/18/2022]
Abstract
The overcoming of catabolite repression, in bioinsecticides production by sporeless Bacillus thuringiensis strain S22 was investigated into fully controlled 3 L fermenter, using glucose based medium. When applying adequate oxygen profile throughout the fermentation period (75% oxygen saturation), it was possible to partially overcome the catabolite repression, normally occurring at high initial glucose concentrations (30 and 40 g/L glucose). Moreover, toxin production yield by sporeless strain S22 was markedly improved by the adoption of the fed-batch intermittent cultures technology. With 22.5 g/L glucose used into culture medium, toxin production was improved by about 36% when applying fed-batch culture compared to one batch. Consequently, the proposed fed-batch strategy was efficient for the overcome of the carbon catabolite repression. So, it was possible to overproduce insecticidal crystal proteins into highly concentrated medium.
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Affiliation(s)
- Saoussen Ben Khedher
- Team of Biopesticides (LPIP), Centre of Biotechnology of Sfax, Sfax University, 3018 Sfax, Tunisia
| | - Samir Jaoua
- Department of Biological & Environmental Sciences, College of Arts and Sciences, Qatar University, P.O. Box 2713, Doha, Qatar
| | - Nabil Zouari
- Department of Biological & Environmental Sciences, College of Arts and Sciences, Qatar University, P.O. Box 2713, Doha, Qatar
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Azzouz H, Kebaili-Ghribi J, ben Farhat-Touzri D, Daoud F, Fakhfakh I, Tounsi S, Jaoua S. Selection and characterisation of an HD1-like Bacillus thuringiensis isolate with a high insecticidal activity against Spodoptera littoralis (Lepidoptera: Noctuidae). PEST MANAGEMENT SCIENCE 2014; 70:1192-1201. [PMID: 24124020 DOI: 10.1002/ps.3661] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 08/16/2013] [Accepted: 10/03/2013] [Indexed: 06/02/2023]
Abstract
BACKGROUND Spodoptera littoralis (Boisduval) larvae are known by their susceptibility to Bacillus thuringiensis subsp. aizawai strains. In order to prevent the appearance of B. thuringiensis (Bt) resistance and to develop economical Bt-based biopesticides, the selection and the characterisation of a B. thuringiensis isolate toxic against S. littoralis larvae and overproducing δ-endotoxins were investigated. RESULTS Among 124 Tunisian B. thuringiensis isolates assessed against S. littoralis larvae, four isolates showed toxicity similar to and higher than the toxicity of the aizawai strain HD133 and the kurstaki strain HD1 respectively. The plasmid pattern of the selected isolates was similar to that of HD1. Polymerase chain reaction (PCR) analysis using specific primers revealed that these isolates present different gene contents. The only detected gene encoding Spodoptera-specific toxin was cry9. The selected isolates were found to produce bipyramidal and cubic crystals. The assessment of δ-endotoxin production by these isolates showed that BUPM28 produced 43.71 and 80.81% more δ-endotoxin than HD1 and HD133 respectively. The application of osmotic or heat shock stress on the BUPM28 isolate made it possible to enhance δ-endotoxin production by 22 and 23% respectively. CONCLUSION On the basis of its potent insecticidal activity and its high level of δ-endotoxin production, the BUPM28 isolate can be considered to be an effective alternative for the control of S. littoralis.
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Affiliation(s)
- Hichem Azzouz
- Laboratory of Plant Protection and Improvement (Biopesticides Team), Centre of Biotechnology of Sfax, Sfax University, Sfax, Tunisia
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Ben Khedher S, Jaoua S, Zouari N. Application of statistical experimental design for optimisation of bioinsecticides production by sporeless Bacillus thuringiensis strain on cheap medium. Braz J Microbiol 2014; 44:927-33. [PMID: 24516462 PMCID: PMC3910214 DOI: 10.1590/s1517-83822013000300043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Accepted: 11/13/2012] [Indexed: 11/21/2022] Open
Abstract
In order to overproduce bioinsecticides production by a sporeless Bacillus thuringiensis strain, an optimal composition of a cheap medium was defined using a response surface methodology. In a first step, a Plackett-Burman design used to evaluate the effects of eight medium components on delta-endotoxin production showed that starch, soya bean and sodium chloride exhibited significant effects on bioinsecticides production. In a second step, these parameters were selected for further optimisation by central composite design. The obtained results revealed that the optimum culture medium for delta-endotoxin production consists of 30 g L−1 starch, 30 g L−1 soya bean and 9 g L−1 sodium chloride. When compared to the basal production medium, an improvement in delta-endotoxin production up to 50% was noted. Moreover, relative toxin yield of sporeless Bacillus thuringiensis S22 was improved markedly by using optimised cheap medium (148.5 mg delta-endotoxins per g starch) when compared to the yield obtained in the basal medium (94.46 mg delta-endotoxins per g starch). Therefore, the use of optimised culture cheap medium appeared to be a good alternative for a low cost production of sporeless Bacillus thuringiensis bioinsecticides at industrial scale which is of great importance in practical point of view.
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Affiliation(s)
- Saoussen Ben Khedher
- Team of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia
| | - Samir Jaoua
- Team of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia. ; Biological and Environmental Sciences Department, College of Arts and Sciences, Qatar University, Doha, Qatar
| | - Nabil Zouari
- Team of Biopesticides, Centre of Biotechnology of Sfax, University of Sfax, Sfax, Tunisia. ; Biological and Environmental Sciences Department, College of Arts and Sciences, Qatar University, Doha, Qatar
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Ben Khedher S, Kamoun A, Jaoua S, Zouari N. Improvement of Bacillus thuringiensis bioinsecticide production by sporeless and sporulating strains using response surface methodology. N Biotechnol 2011; 28:705-12. [PMID: 21310269 DOI: 10.1016/j.nbt.2011.01.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 01/06/2011] [Accepted: 01/31/2011] [Indexed: 10/18/2022]
Abstract
Statistical experimental designs, involving a Plackett-Burman design followed by a rotatable central composite design were used to optimize the culture medium constituents for Bacillus thuringiensis bioinsecticide production. This was carried out by using firstly an asporogenic strain and extrapolated to some sporeless and sporulating strains. Initial screening of production parameters was performed and the variables with statistically significant effects on delta-endotoxin production were identified: glucose, glycerol, yeast extract and MnSO(4). These variables were selected for further optimization by response surface methodology. The obtained results revealed that the optimum culture medium for delta-endotoxin production consists of 22.5 g/l of glucose, 4.8g/l of glycerol, 5.8 g/l of yeast extract and 0.008 g/l of MnSO(4). Under these conditions, delta-endotoxin production was 2,130 and 2,260 mg/l into 250 and 1,000 ml flask respectively, which represent more than 38% improvement in toxin production over the basal medium (1,636 mg/l). Such medium composition was shown to be suitable for overproducing delta-endotoxins by sporeless and sporulating strains.
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Affiliation(s)
- Saoussen Ben Khedher
- Laboratoire de Protection et Amélioration des Plantes (Equipe Biopesticides), Center of Biotechnology of Sfax, University of Sfax, P.O. Box 1177, 3018 Sfax, Tunisia
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Ben Khedher S, Jaoua S, Zouari N. Improvement of bioinsecticides production by sporeless Bacillus thuringiensis strains in response to various stresses in low cost medium. Curr Microbiol 2011; 62:1467-77. [PMID: 21305292 DOI: 10.1007/s00284-011-9884-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Accepted: 01/17/2011] [Indexed: 11/30/2022]
Abstract
The use of bioinsecticides, particularly those produced by sporeless Bacillus thuringiensis strains, has been shown to be a good alternative in pest management. Two types of sporeless mutants were distinguished. The asporogenic mutants which completely lack spores produce a regular bipyramidal crystal inclusion. The oligosporogenic mutants kept the ability to produce insecticidal crystal proteins. However, sporulation in such mutants was not totally blocked and very few of them could still produce spores. In order to improve bioinsecticides production, adaptation of sporeless strains to heat shock and osmotic stress was investigated. Delta-endotoxin production by 78% of sporeless mutants was significantly improved by osmotic stress with an overproduction of about 17%, compared to the wild strain BNS3. However, toxin production was improved by only 21% of mutants after heat shock, in low cost medium. The statistical analysis proved that delta-endotoxin production, cell growth, and spore formation of asporogenic and oligosporogenic mutants depended on the type of applied stress. Each strain has an important potential when applying the adequate stress. Moreover, adaptation of sporeless mutants to NaCl may allow the substitution of all minerals of the medium by diluted sea water which appeared to be a good alternative for the economic production of bioinsecticides at industrial scale which is of great importance from the practical point of view.
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Affiliation(s)
- Saoussen Ben Khedher
- Laboratoire de Protection et Amélioration des Plantes (Equipe Biopesticides), Center of Biotechnology of Sfax, 1177, 3018 Sfax, Tunisia
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