Effects of Alcohol Compounds on the Growth and Lipid Accumulation of Oleaginous Yeast Trichosporon fermentans

Abstract

The inhibitors present in dilute acid-treated lignocellulosic hydrolysates would show great effect on the growth and product formation of microorganisms. To understand their inhibitory law and mechanism on oleaginous microorganism could help improving the efficiency of lignocellulose hydrolysis, detoxification, and lipid fermentation. The effects of four representative alcohol compounds present in lignocellulosic hydrolysates, including furfuryl alcohol, vanillyl alcohol, catechol, hydroquinone on the cell growth and lipid accumulation of Trichosporon fermentans were systematically investigated in this work. The toxicity of selected alcohol compounds was well related to their log P value except furfuryl alcohol, whose log P value was the minimum but with the highest toxicity to T. fermentans. The inhibition of all the alcohol compounds on the growth of T. fermentans was more serious than on the lipid synthesis. Also, the growth of T. fermentans was more sensitive to the variation of inoculum size, temperature, and initial pH than lipid synthesis in the presence of alcohol compounds. Initial pH had more profound influence on the lipid fermentation than inoculum size and cultural temperature did. Careful control of fermentation conditions could be helpful for improving lipid yield of T. fermentans in lignocellulosic hydrolysates. Among the four alcohol compounds tested, most alcohol compounds showed inhibition on both sugar consumption and malic enzyme activity of T. fermentans. However, vanillyl alcohol had little influence on the malic enzyme activity. Similarly, all alcohol compounds except vanillyl alcohol exerted damage on the cell membrane of T. fermentans.

Production of single cell oil from Lipomyces starkeyi ATCC 56304 using biorefinery by-products

“…The deleterious effect of inhibitory compounds including acetic acid, HMF, and furfural on oleaginous yeast growth and lipid accumulation has been well-documented by others (Huang et al, 2011;Hu et al, 2009;Chen et al, 2009) and confirmed by our study. While the effect of each inhibitor may vary across oleaginous yeast species and cultivation conditions, multiple studies have reported that furfural has a higher degree of inhibition compared to HMF (Huang et al, 2011;Chen et al, 2009;Zhao et al, 2012;Hu et al, 2009). This may account for the lower oil yields obtained using destarched hydrolysates which had a higher level of furfural compared to the whole bran hydrolysates (Fig.…”

Effects of lignocellulose-derived inhibitors on growth and succinic acid accumulation by Corynebacterium glutamicum

“…1A and 1B). Furfural and 5-hydroxymethylfurfural are two furan derivatives, Chao Huang previously reported these two furans displayed lower toxicity to T. fermentans [7], however, some repoted Escherichia coli ATCC 1175, Z. mobilis ATCC 10988 and E. coli LY01 are more sensitive to furfural, the cell growth of those microorganism significantly decreased with the increase in concentration of furfural and 5-hydroxymethylfurfural [23][24][25], our results displayed C. glutamicum NC-1 showed some tolerance to furfural and 5-hydroxymethylfurfural at low concentration (above 1 g/L, Figs. 1A and 1B).…”

“…Malic enzyme is usually considered as the key one of the main enzymes in Krebs cycle, providing a supply of NADH to microorganisms [35]. Chao Huang reported the malic enzyme activity was inhibited while added aldehydes into medium for lipid synthesis in oleaginous microorganism [7]. In order to understand the effects of aldehydes on succinic acid accumulation under oxygen deprivation by C. glutamicum NC-1, so malic enzyme activity was detected while in accumulating succinic acid fermentation phase (Fig.…”

“…However, feedstocks of current biotechnology production methods are currently derived from edible parts of food crops such as sugarcane and corn, this leads to an undesirable direct competition between biotechnology production and the food supply [4][5][6]. Lignocellulosic biomass is regard as the most available, renewable, and green source of sugars [7], so it has a potential of being supplied in large-scale industrial production.…”

“…In most cases, these byproducts, known as inhibitors, exert negative effects on the growth, metabolism, and product formation of microbial cells [16][17][18][19]. The effect of inhibitors in lignocellulosic hydrolysates on the growth and product accumulation by various microorganisms has been studied by some researchers [6,7]. However, there have been few reports about the influence of inhibitors on the succinic acid accumulation by C. glutamicum NC-1.…”