Kinetic study of succinic acid production by Actinobacillus succinogenes ZT-130 Rosa Isela Corona-Gonza´ lez a, *, Andre Bories b , Vı´ctor Gonza´ lez-A ´ lvarez a , Carlos Pelayo-Ortiz a a Laboratorio de Biotecnologı´a, Centro Universitario de Ciencias Exactas e Ingenierı´a, Universidad de Guadalajara, Blv. Marcelino Garcı´a Barraga´n #1421, C.P. 44430, Guadalajara, Jalisco, Mexico b Institut National de la Recherche Agronomique, Unite´ Expe´rimentale de Pech Rouge, 11430 Gruissan, France 1. Introduction Succinic acid is an intermediate in the tricarboxylic acid cycle during aerobic metabolism, and an end product during anaerobic metabolism. Recently, this acid has attracted great interest because it can be used as a precursor for different chemical reagents, synthetic resins, biodegradable polymers, herbicides, fungicides, inks, and detergents, among other products [1,2]. This acid is also used as a plant growth regulator; it also increases the metabolic efficiency in farm cattle [3,4]. Commercially, succinic acid can be produced petrochemically from butane [1,5]; however, the high conversion cost of maleic anhydride to succinic acid by the chemical process, which limits the use of succinic acid in numerous applications [6]. The interest in producing succinic acid by fermentative processes from renewable resources has increased during the last decade owing to environmental [5] and economical concerns. Recently, economical analyses have shown that fermen- tative production of succinic acid from renewable resources could be more cost-effective than the petroleum-based processes [6]. Even though many bacteria are able to produce succinic acid, it is the main product for just a few of the bacteria [7,8]. Most of the microorganisms used to produce succinic acid are isolated from bovine rumen. Strains genetically modified from Anaerobiospir- illum succiniciproducens [9–11] and Escherichia coli have been reported as producers of succinic acid with high levels of concentration, 65 and 45 g/l, respectively [1,12]. A transformed strain (AFP111/pTrc99A-pyc) from E coli AFP111 using dual-phase fermentations, achieved a final succinic acid concentration of 99.2 g/l with an overall yield of 110% and productivity of 1.3 g/l h [13]. However, other studies show that Actinobacillus succinogenes ZT-130 (bacteria isolated from bovine rumen) variant strains can yield 110 g/l using glucose as a substrate [1,14]. The economic feasibility of microbial production of succinic acid depends on the efficiency of the process and the final concentration of the product [15]. Different studies on succinic acid production have been carried out to obtain information about different microorganisms, including A. succinogenes, metabolic pathways [3], and character- ization of enzymes and regulation modes involved in the production of succinic acid [16,7]. The importance of the oxidation–reduction conditions [17] lactose and glucose utiliza- tion in batch and continuous reactors by Anaerobiospirillum succinicicproducens for succinic acid production has been described [2] but there is no detailed kinetic study on glucose concentration and its effect on A. succinogenes growth and succinic acid production. This paper presents a kinetic study of glucose conversion to succinic acid using several initial concentrations of glucose in a batch fermentation of A. succinogenes. Substrate and product inhibition was detected through the fermentative profile (biomass and product concentration) and kinetic expressions were devel- oped to describe them. Finally, fermentation strategies to optimize the production of succinic acid are suggested. Process Biochemistry 43 (2008) 1047–1053 ARTICLE INFO Article history: Received 18 January 2007 Received in revised form 7 March 2008 Accepted 19 May 2008 Keywords: Succinic acid Actinobacillus succinogenes Inhibitory effect Glucose concentration Kinetic study Acid mixture concentration ABSTRACT The effect of different glucose concentrations (10–100 g/l) on succinic acid production by Actinobacillus succinogenes was studied. The maximum succinic acid concentration obtained was 33.8 g/l from 54.7 g/l of glucose. Productivities, conversion yields, and specific rates decreased when the amount of initial glucose was increased. The growth stopped with 22 g/l of acid mixture produced (succinic, formic, and acetic acids) and succinic acid production stopped with 45 g/l of acid mixture produced. These results point to a double inhibitory effect by glucose and products on growth and succinic acid production. The inhibition phenomenon was adequately described by Jerusalimsky equations for specific rate of growth and specific rate of succinic acid production. These expressions helped to quantify substrate and product inhibition effects. ß 2008 Elsevier Ltd. All rights reserved. * Corresponding author. Fax: +52 33 36503401. E-mail address: rcoronagonzalez@yahoo.com (R.I. Corona-Gonza´ lez). Contents lists available at ScienceDirect Process Biochemistry journal homepage: www.elsevier.com/locate/procbio 1359-5113/$ – see front matter ß 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.procbio.2008.05.011