Continuous multistep versus fed‐batch production of ethanol and xylitol in a simulated medium of sugarcane bagasse hydrolyzates

Abstract

Co-cultures for simultaneous production of ethanol and xylitol were studied under different operation bioreactor modes using Candida tropicalis IEC5-ITV and Saccharomyces cerevisiae ITV01-RD in a simulated medium of sugarcane bagasse hydrolyzates. Xylitol and ethanol tolerance by S. cerevisiae and C. tropicalis, respectively, was evaluated. The results showed that C. tropicalis was sensitive to ethanol concentrations up to 30 g/L, while xylitol had no effect on S. cerevisiae viability and metabolism. The best condition found for simultaneous culture was S. cerevisiae co-culture and C. tropicalis sequential cultivation at 24 h. Under these conditions, productivity and yield for ethanol were Q EtOH = 0.72 g L −1 h −1 and Y EtOH/s = 0.37 g/g, and for xylitol, Q XylOH = 0.10 g L −1 h −1 and Y XylOH/S = 0.31 g/g, respectively; using fed-batch culture, the results wereand Y EtOH/s = 0.57 g/g, respectively. Maximum volumetric productivity in continuous multistep cultures of ethanol and xylitol was at dilution rates of 0.131 and 0.074 h −1 , respectively. Continuous multistep production, Q EtOH increased up to 50% more than in fed-batch culture, even though xylitol yield remained unchanged.

Production of 2,3‐butanediol by fermentation of enzymatic hydrolysed bagasse from agave mezcal‐waste using the native Klebsiella oxytoca UM2‐17 strain

“…This finding suggests that K. oxytoca UM2‐17 redirected its metabolism towards biomass generation. These results contrast with those of Asenjo and Merchuk (1994), where yeast extract and peptone supplementation maintained alcohol production rate and improved 2,3‐butanediol production …”

“…These results contrast with those of Asenjo and Merchuk (1994), 38 where yeast extract and peptone supplementation maintained alcohol production rate and improved 2,3-butanediol production. [39][40][41][42] The 2,3-butanediol yield is dependent on the sugar concentration used in the fermentation medium 2 ; the suitable sugar concentration range to produce 2,3-butanediol with maximal yield was defined as 20-100 g L −1 of glucose or xylose, because exceeding 150 g L −1 causes cellular inhibition, probably due to accumulation of subproducts such as ethanol and acetate [ Fig. 1(a)].…”

Production of bioalcohols and antioxidant compounds by acid hydrolysis of lignocellulosic wastes and fermentation of hydrolysates with Hansenula polymorpha

“…At the same temperature (30ºC) and working in batch, Castañón–Rodríguez et al. using simulated hydrolysates of sugarcane bagasse hydrolysates, with C. tropicalis and S. cerevisiae , obtain higher overall yields in ethanol ( = 0.37 g/g) and xylitol (= 0.31 g/g) although less productivity in biomass. However, in this work at 50ºC the xylitol yield was higher when in the fermentation H. polymorpha was used.…”

Ethanol from Biomass Hydrolysates by Efficient Fermentation of Glucose and Xylose – A Review

“…Castañón‐Rodríguez et al. studied sequential batch culture using C. tropicalis and S. cerevisiae in simulated sugarcane bagasse. This showed that C. tropicalis was sensitive to ethanol concentrations above 30 g L −1 .…”

“…C. shehatae was initially used for glucose and xylose fermentation before adding a high-ethanol-tolerant yeast, either S. cerevisiae or B. bruxellensis, for cellobiose fermentation [141]. Castañón-Rodríguez et al [143] studied sequential batch culture using C. tropicalis and S. cerevisiae in simulated sugarcane bagasse. This showed that C. tropicalis was sensitive to ethanol concentrations above 30 g L -1 .…”