Inactivation of guanylate kinase in Bacillus sp. TL7-3 cultivated under an optimized ratio of carbon and nitrogen sources influenced GTP regeneration capability and sporulation
Phetcharat Jaiaue,
Piroonporn Srimongkol,
Sitanan Thitiprasert,
Jirabhorn Piluk,
Jesnipit Thammaket,
Suttichai Assabumrungrat,
Benjamas Cheirsilp,
Somboon Tanasupawat,
Nuttha Thongchul
Affiliations
Phetcharat Jaiaue
Program in Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
Piroonporn Srimongkol
Center of Excellence in Bioconversion and Bioseparation for Platform Chemical Production, Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, Thailand; Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, Thailand
Sitanan Thitiprasert
Center of Excellence in Bioconversion and Bioseparation for Platform Chemical Production, Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, Thailand; Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, Thailand; Corresponding author.
Jirabhorn Piluk
Center of Excellence in Bioconversion and Bioseparation for Platform Chemical Production, Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, Thailand; Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, Thailand; Corresponding author. Center of Excellence in Bioconversion and Bioseparation for Platform Chemical Production, Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, Thailand.
Jesnipit Thammaket
Program in Biotechnology, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
Suttichai Assabumrungrat
Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, Thailand
Benjamas Cheirsilp
Department of Industrial Biotechnology, Faculty of Agro-Industry, Prince of Songkla University, Songkla, Thailand
Somboon Tanasupawat
Department of Biochemistry and Microbiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand
Nuttha Thongchul
Center of Excellence in Bioconversion and Bioseparation for Platform Chemical Production, Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, Thailand; Institute of Biotechnology and Genetic Engineering, Chulalongkorn University, Bangkok, Thailand; Corresponding author.
Bacillus sp. TL7-3 has potential as a dietary supplement to promote human and animal health. It produces spores that can survive in harsh environments. Thus, when supplemented with nutrients, these spores can withstand the acidic pH of the stomach and resume vegetative development in the gut when exposed to growth-promoting conditions. Spores are formed as a cellular defense mechanism when a culture experiences stress and process optimization to achieve high spore production in a typical batch process remains challenging. Existing literature on the manipulation of gene expression and enzyme activity during batch cultivation is limited. Studies on the growth patterns, morphological changes, and relevant gene expression have aided in enhancing spore production. The present study used the response surface methodology for medium optimization. The model suggested that yeast extract and NH4Cl were significant factors controlling spore production. A comparison between the high weight ratio of carbon and nitrogen (C:N) substrates (8.57:1) in the optimized and basal media (0.52:1) showed an 8.76-fold increase in the final spore concentration. The expression of major genes, including codY, spo0A, kinA, and spo0F, involved in the sporulation was compared when cultivating Bacillus sp. TL7-3 in media with varying C:N ratios. At high C:N ratios, spo0A, kinA, and spo0F were upregulated, whereas codY was downregulated. This led to decreased guanylate kinase activity, resulting in a low guanosine triphosphate concentration and inactivation of CodY, thereby reducing the repression of spo0A and CodY-repressed genes and stimulating sporulation.
