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Liu Z, Wu Y, Zhang L, Tong S, Jin J, Gong X, Zhong J. rocF affects the production of tetramethylpyrazine in fermented soybeans with Bacillus subtilis BJ3-2. BMC Biotechnol 2022; 22:18. [PMID: 35787694 PMCID: PMC9254598 DOI: 10.1186/s12896-022-00748-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 06/29/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Tetramethylpyrazine (TTMP) is a flavoring additive that significantly contributes to the formation of flavor compounds in soybean-based fermented foods. Over recent years, the application of TTMP in the food industry and medicine has been widely investigated. In addition, several methods for the industrial-scale production of TTMP, including chemical and biological synthesis, have been proposed. However, there have been few reports on the synthesis of TTMP through amino acid metabolic flux. In this study, we investigated genetic alterations of arginine metabolic flux in solid-state fermentation (SSF) of soybeans with Bacillus subtilis (B.subtilis) BJ3-2 to enhance the TTMP yield. RESULTS SSF of soybeans with BJ3-2 exhibited a strong Chi-flavour (a special flavour of ammonia-containing smelly distinct from natto) at 37 °C and a prominent soy sauce-like aroma at 45 °C. Transcriptome sequencing and RT-qPCR verification showed that the rocF gene was highly expressed at 45 °C but not at 37 °C. Moreover, the fermented soybeans with BJ3-2ΔrocF (a rocF knockout strain in B. subtilis BJ3-2 were obtained by homologous recombination) at 45 °C for 72 h displayed a lighter color and a slightly decreased pH, while exhibiting a higher arginine content (increased by 14%) than that of BJ3-2. However, the ammonia content of fermented soybeans with BJ3-2ΔrocF was 43% lower than that of BJ3-2. Inversely, the NH4+ content in fermented soybeans with BJ3-2ΔrocF was increased by 28% (0.410 mg/kg). Notably, the TTMP content in fermented soybeans with BJ3-2ΔrocF and BJ3-2ΔrocF + Arg (treated with 0.05% arginine) were significantly increased by 8.6% (0.4617 mg/g) and 18.58% (0.504 mg/g) respectively than that of the BJ3-2. CONCLUSION The present study provides valuable information for understanding the underlying mechanism during the TTMP formation process through arginine metabolic flux.
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Affiliation(s)
- Zhenli Liu
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology & Agro-Bioengineering (CICMEAB), College of Life Sciences/Institute of Agro-Bioengineeringering, Guizhou University, Guiyang, 550025, Guizhou, China
| | - Yongjun Wu
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology & Agro-Bioengineering (CICMEAB), College of Life Sciences/Institute of Agro-Bioengineeringering, Guizhou University, Guiyang, 550025, Guizhou, China.
| | - Lincheng Zhang
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology & Agro-Bioengineering (CICMEAB), College of Life Sciences/Institute of Agro-Bioengineeringering, Guizhou University, Guiyang, 550025, Guizhou, China
| | - Shuoqiu Tong
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology & Agro-Bioengineering (CICMEAB), College of Life Sciences/Institute of Agro-Bioengineeringering, Guizhou University, Guiyang, 550025, Guizhou, China
| | - Jing Jin
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology & Agro-Bioengineering (CICMEAB), College of Life Sciences/Institute of Agro-Bioengineeringering, Guizhou University, Guiyang, 550025, Guizhou, China
| | - Xian Gong
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology & Agro-Bioengineering (CICMEAB), College of Life Sciences/Institute of Agro-Bioengineeringering, Guizhou University, Guiyang, 550025, Guizhou, China
| | - Jie Zhong
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Collaborative Innovation Center for Mountain Ecology & Agro-Bioengineering (CICMEAB), College of Life Sciences/Institute of Agro-Bioengineeringering, Guizhou University, Guiyang, 550025, Guizhou, China
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Zhu BF, Xu Y. Production of tetramethylpyrazine by batch culture of Bacillus subtilis with optimal pH control strategy. J Ind Microbiol Biotechnol 2010; 37:815-21. [PMID: 20437078 DOI: 10.1007/s10295-010-0726-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2009] [Accepted: 04/14/2010] [Indexed: 10/19/2022]
Abstract
The effects of initial culture pH ranging from 5.0 to 7.5 on biomass content, precursor 3-hydroxy-2-butanone (HB) accumulation, and 2,3,5,6-tetramethylpyrazine (TTMP) formation by Bacillus subtilis CCTCC M 208157 were investigated in shake flask fermentation. Weak acidic conditions were found to favor cell growth and precursor HB accumulation, while TTMP could be synthesized more efficiently in conditions with initial pH towards neutrality. Batch bioprocess of TTMP fermentation by Bacillus subtilis CCTCC M 208157 at various controlled pH values ranging from 5.5 to 7.0 was then examined in 7.5-l fermentor. The results suggested that optimum pH for cell growth and precursor HB accumulation was 5.5 with maximum cell growth rate (Q (x)) and precursor HB accumulation rate (Q (HB)) of 0.833 g l(-1) h(-1) and 1.118 g l(-1) h(-1), respectively, while optimum pH for TTMP formation was 7.0 with maximum TTMP formation rate (Q (TTMP)) of 0.095 g l(-1) h(-1). A pH-shifted strategy was accordingly developed to improve TTMP production in bioreactor fermentation by shifting the culture pH from 5.5 to 7.0 after 48 h of cultivation. By applying the strategy, final TTMP concentration of 7.43 g l(-1) was obtained, being 22.2% greater than that of constant-pH fermentation.
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Affiliation(s)
- Bing-Feng Zhu
- State Key Laboratory of Food Science and Technology, Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, 214122 Wuxi, Jiangsu, China
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Wolken WAM, Tramper J, van der Werf MJ. Toxicity of terpenes to spores and mycelium of Penicillium digitatum. Biotechnol Bioeng 2002; 80:685-90. [PMID: 12378610 DOI: 10.1002/bit.10435] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Spores, although often considered metabolically inert, catalyze a variety of reactions. The use of spores instead of mycelium for bioconversions has several advantages. In this paper, we describe the difference in susceptibility of mycelium and spores against toxic substrates and products. A higher resistance of spores toward the toxic effects of bioconversion substrates and products is an advantage that has not been studied in detail until now. This paper shows that spores of Penicillium digitatum ATCC 201167 are on average over 2.5 times more resistant than mycelium toward the toxicity of substrates, intermediates, and products of the geraniol bioconversion pathway. Furthermore, the higher resistance of spores to citral was shown as an advantage in its biotransformation by P. digitatum. Using three different approaches the toxicity of the compounds were tested. The order of toxicity toward P. digitatum was, starting with the most toxic, citral > nerol/geraniol > geranic acid > methylheptenone >> acetaldehyde.
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Affiliation(s)
- Wout A M Wolken
- Division of Industrial Microbiology, Department of Food Technology and Nutritional Sciences, Wageningen University, Wageningen, The Netherlands.
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