title: Influence of carbon sources on the viability and resuscitation of Acetobacter senegalensis during high-temperature gluconic acid fermentation.
abstract: Much research has been conducted about different types of fermentation at high temperature, but only a few of them have studied cell viability changes during high-temperature fermentation. In this study, Acetobacter senegalensis, a thermo-tolerant strain, was used for gluconic acid production at 38 °C. The influences of different carbon sources and physicochemical conditions on cell viability and the resuscitation of viable but nonculturable (VBNC) cells formed during fermentation were studied. Based on the obtained results, A. senegalensis could oxidize 95 g l- 1glucose to gluconate at 38 °C (pH 5.5, yield 83%). However, despite the availability of carbon and nitrogen sources, the specific rates of glucose consumption (qs) and gluconate production (qp) reduced progressively. Interestingly, gradual qsand qpreduction coincided with gradual decrease in cellular dehydrogenase activity, cell envelope integrity, and cell culturability as well as with the formation of VBNC cells. Entry of cells into VBNC state during stationary phase partly stemmed from high fermentation temperature and long-term oxidation of glucose, because just about 48% of VBNC cells formed during stationary phase were resuscitated by supplementing the culture medium with an alternative favorite carbon source (low concentration of ethanol) and/or reducing incubation temperature to 30 °C. This indicates that ethanol, as a favorable carbon source, supports the repair of stressed cells. Since formation of VBNC cells is often inevitable during high-temperature fermentation, using an alternative carbon source together with changing physicochemical conditions may enable the resuscitation of VBNC cells and their use for several production cycles.
authors.affiliation: Department of Biology, Faculty of Sciences, University of Isfahan, Isfahan, Iran.
authors.forename: Rasoul
authors.initials: R
authors.lastname: Shafiei
authors.affiliation: Walloon Center for Industrial Biology, University of Liège, Bld. du Rectorat 29, Sart-Tilman, 4000, Liège, Belgium. r.zarmehrkhorshid@doct.ulg.ac.be.|Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, Bio-Industry Unit, University of Liège, 5030, Gembloux, Belgium. r.zarmehrkhorshid@doct.ulg.ac.be.
authors.forename: Raziyeh
authors.initials: R
authors.lastname: Zarmehrkhorshid
authors.affiliation: Hassan II Institute of Agronomy and Veterinary Medicine (IAV), PB 6202, Rabat, Morocco.
authors.forename: Majid
authors.initials: M
authors.lastname: Mounir
authors.affiliation: Department of Biology, Faculty of Sciences, University of Isfahan, Isfahan, Iran.|Walloon Center for Industrial Biology, University of Liège, Bld. du Rectorat 29, Sart-Tilman, 4000, Liège, Belgium.|Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, Bio-Industry Unit, University of Liège, 5030, Gembloux, Belgium.
authors.forename: Philippe
authors.initials: P
authors.lastname: Thonart
authors.affiliation: Microbial Processes and Interactions (MiPI), Gembloux Agro-Bio Tech, Bio-Industry Unit, University of Liège, 5030, Gembloux, Belgium.
authors.forename: Frank
authors.initials: F
authors.lastname: Delvigne
mesh_terms: D000091:Acetobacter / Q000378:metabolism*; D005285:Fermentation; D005942:Gluconates / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006358:Hot Temperature; D050296:Microbial Viability; D010084:Oxidation-Reduction
chemical_list: D005942:Gluconates; D005947:Glucose; C030691:gluconic acid
keywords: Acetobacter senegalensis; Gluconic acid; High-temperature fermentation; Resuscitation; VBNC