Limits...
Evaluating the effects of biocompatible cholinium ionic liquids on microbial lipid production by Trichosporon fermentans.

Liu L, Hu Y, Wen P, Li N, Zong M, Ou-Yang B, Wu H - Biotechnol Biofuels (2015)

Bottom Line: Despite the reduction in lipid content, the lipid production by T. fermentans was improved in the presence of low concentrations of [Ch][Lys] (≤30 mM) and [Ch][Ser] (≤20 mM) due to the remarkable increase of biomass.However, the anions of [Ch][Lys] and [Ch][Ser] could be assimilated as nitrogen source by T. fermentans and the reduced C/N ratio accounts for the inhibition of lipid accumulation, which could be alleviated by improving C/N ratio of medium.The anions of [Ch][Lys], [Ch][Ser] and [Ch][OAc] play an important role in affecting the cell growth and lipid accumulation of T. fermentans, and the inhibition of these three ILs on lipid production can be alleviated by careful fermentation condition control.

View Article: PubMed Central - PubMed

Affiliation: School of Biosciences and Bioengineering, Guangzhou Higher Education Mega Centre, South China University of Technology, 382 East Waihuan Rd., Panyu District, Guangzhou, 510640 China.

ABSTRACT

Background: Microbial lipid is a potential raw material for large-scale biodiesel production and lignocellulosic hydrolysate has been considered as promising low-cost substrate for lipid fermentation. Lignocellulosic biomass needs to be pretreated before enzymatic hydrolysis, and biocompatible cholinium ionic liquids (ILs) have been demonstrated to be highly efficient for pretreatment. However, the impact of these ILs residues in hydrolysates on downstream biotransformation remains unknown. Therefore, the influence of three typical cholinium ILs on the lipid production by Trichosporon fermentans was first investigated.

Results: The cell growth of T. fermentans was stimulated in the presence of cholinium lysine ([Ch][Lys]) and cholinium serine ([Ch][Ser]), while the lipid accumulation was inhibited by [Ch][Lys]) and [Ch][Ser]. Both cell growth and lipid accumulation of T. fermentans were inhibited in the presence of cholinium acetate ([Ch][OAc]). Despite the reduction in lipid content, the lipid production by T. fermentans was improved in the presence of low concentrations of [Ch][Lys] (≤30 mM) and [Ch][Ser] (≤20 mM) due to the remarkable increase of biomass. It was found that cholinium cation had minor influence on lipid production. However, the anions of [Ch][Lys] and [Ch][Ser] could be assimilated as nitrogen source by T. fermentans and the reduced C/N ratio accounts for the inhibition of lipid accumulation, which could be alleviated by improving C/N ratio of medium. In addition, the anion of [Ch][OAc] could be metabolized by T. fermentans, leading to a rapid alkaline-pH shift and strong inhibition of lipid production. And this inhibitory effect on lipid production could be significantly reduced by controlling culture pH.

Conclusions: The anions of [Ch][Lys], [Ch][Ser] and [Ch][OAc] play an important role in affecting the cell growth and lipid accumulation of T. fermentans, and the inhibition of these three ILs on lipid production can be alleviated by careful fermentation condition control. Hence, T. fermentans is a promising strain for microbial lipid production from cholinium ILs-pretreated lignocellulosic hydrolysates.

No MeSH data available.


Related in: MedlinePlus

Lipid production by T. fermentans in the presence of [Ch][Lys], [Ch][Ser], and [Ch][OAc]. a Biomass, b lipid concent, and c lipid yield of T. fermentans in the presence of the cholinium ILs. d The evolution of the concentrations of [Lys]−, [Ser]− and [OAc]− in the fermentation media against time. The results are mean of two experiments, and error bars represent standard deviations from mean value.
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Fig1: Lipid production by T. fermentans in the presence of [Ch][Lys], [Ch][Ser], and [Ch][OAc]. a Biomass, b lipid concent, and c lipid yield of T. fermentans in the presence of the cholinium ILs. d The evolution of the concentrations of [Lys]−, [Ser]− and [OAc]− in the fermentation media against time. The results are mean of two experiments, and error bars represent standard deviations from mean value.

Mentions: As depicted in Fig. 1a, [Ch][Lys] could significantly stimulate the cell growth of T. fermentans except at 5 mM (p < 0.05). The biomass increased with the increase of [Ch][Lys] concentration and reached its maximum of 24.2 g/L at 30 mM, which was 171% of that obtained in the absence of IL (14.2 g/L). Further increase in the [Ch][Lys] concentration above 30 mM led to a slight drop in biomass. However, even at 60 mM, the biomass still reached 20.9 g/L which was 47.5% higher than the control. In contrast, the lipid content of T. fermentans decreased with the increase of [Ch][Lys] concentration (except at 5 mM), indicating that [Ch][Lys] had an inhibitory effect on lipid accumulation of T. fermentans (Fig. 1b). When [Ch][Lys] was at 60 mM, the lipid content of T. fermentans was only 28.5%, reduced by 52.4% compared with that obtained in the absence of the IL (28.5 vs. 59.9%). As can be seen in Fig. 1c, despite of the reduction in lipid content, the lipid production was still improved in the presence of low concentrations of [Ch][Lys] (≤30 mM), which was attributed to the remarkable increase of biomass. For [Ch][Ser], the impact of which on the cell growth and lipid accumulation of T. fermentans was quite similar to that of [Ch][Lys], with features of stimulating cell growth but inhibiting lipid accumulation, and the increase in biomass was significant except at 5 and 60 mM (p < 0.05), while the reduction in lipid content was significant except at 5 mM (p < 0.05). The lipid production was also improved in the presence of low concentrations of [Ch][Ser] (≤20 mM) due to the drastic increase of biomass. However, the biomass and lipid content of T. fermentans in the presence of various concentrations of [Ch][Ser] were all lower than those in the presence of equivalent amounts of [Ch][Lys]. Crépin et al. reported that lysine could be prematurely consumed by S. cerevisiae as nitrogen source [21]. It was also demonstrated that lysine could enhance the cell growth and ethanol production by regulating the nitrogen metabolism of Saccharomyces pastorianus [22]. Therefore, the stimulation effect of [Ch][Lys] and [Ch][Ser] on T. fermentans’ cell growth might be due to its assimilation of the anions of [Ch][Lys] and [Ch][Ser] for synthesis of cellular components, or improving the efficiency of nutrients uptake in the presence of additional ILs. Unlike [Ch][Lys] and [Ch][Ser], both cell growth and lipid accumulation of T. fermentans were inhibited by [Ch][OAc] and the biomass, lipid content, and lipid yield in the presence of 60 mM [Ch][OAc] were reduced by 36.5, 17.2, and 47.1%, respectively, compared with those of the control (Fig. 1a–c). Similar phenomenon was also observed in studying the effect of [Emim][OAc] on lipid production by R. toruloides, and the inhibition of [Emim][OAc] on cell growth and lipid accumulation was attributed to the assimilation of acetate which led to a rapid alkaline-pH shift [13].Fig. 1


Evaluating the effects of biocompatible cholinium ionic liquids on microbial lipid production by Trichosporon fermentans.

Liu L, Hu Y, Wen P, Li N, Zong M, Ou-Yang B, Wu H - Biotechnol Biofuels (2015)

Lipid production by T. fermentans in the presence of [Ch][Lys], [Ch][Ser], and [Ch][OAc]. a Biomass, b lipid concent, and c lipid yield of T. fermentans in the presence of the cholinium ILs. d The evolution of the concentrations of [Lys]−, [Ser]− and [OAc]− in the fermentation media against time. The results are mean of two experiments, and error bars represent standard deviations from mean value.
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4536777&req=5

Fig1: Lipid production by T. fermentans in the presence of [Ch][Lys], [Ch][Ser], and [Ch][OAc]. a Biomass, b lipid concent, and c lipid yield of T. fermentans in the presence of the cholinium ILs. d The evolution of the concentrations of [Lys]−, [Ser]− and [OAc]− in the fermentation media against time. The results are mean of two experiments, and error bars represent standard deviations from mean value.
Mentions: As depicted in Fig. 1a, [Ch][Lys] could significantly stimulate the cell growth of T. fermentans except at 5 mM (p < 0.05). The biomass increased with the increase of [Ch][Lys] concentration and reached its maximum of 24.2 g/L at 30 mM, which was 171% of that obtained in the absence of IL (14.2 g/L). Further increase in the [Ch][Lys] concentration above 30 mM led to a slight drop in biomass. However, even at 60 mM, the biomass still reached 20.9 g/L which was 47.5% higher than the control. In contrast, the lipid content of T. fermentans decreased with the increase of [Ch][Lys] concentration (except at 5 mM), indicating that [Ch][Lys] had an inhibitory effect on lipid accumulation of T. fermentans (Fig. 1b). When [Ch][Lys] was at 60 mM, the lipid content of T. fermentans was only 28.5%, reduced by 52.4% compared with that obtained in the absence of the IL (28.5 vs. 59.9%). As can be seen in Fig. 1c, despite of the reduction in lipid content, the lipid production was still improved in the presence of low concentrations of [Ch][Lys] (≤30 mM), which was attributed to the remarkable increase of biomass. For [Ch][Ser], the impact of which on the cell growth and lipid accumulation of T. fermentans was quite similar to that of [Ch][Lys], with features of stimulating cell growth but inhibiting lipid accumulation, and the increase in biomass was significant except at 5 and 60 mM (p < 0.05), while the reduction in lipid content was significant except at 5 mM (p < 0.05). The lipid production was also improved in the presence of low concentrations of [Ch][Ser] (≤20 mM) due to the drastic increase of biomass. However, the biomass and lipid content of T. fermentans in the presence of various concentrations of [Ch][Ser] were all lower than those in the presence of equivalent amounts of [Ch][Lys]. Crépin et al. reported that lysine could be prematurely consumed by S. cerevisiae as nitrogen source [21]. It was also demonstrated that lysine could enhance the cell growth and ethanol production by regulating the nitrogen metabolism of Saccharomyces pastorianus [22]. Therefore, the stimulation effect of [Ch][Lys] and [Ch][Ser] on T. fermentans’ cell growth might be due to its assimilation of the anions of [Ch][Lys] and [Ch][Ser] for synthesis of cellular components, or improving the efficiency of nutrients uptake in the presence of additional ILs. Unlike [Ch][Lys] and [Ch][Ser], both cell growth and lipid accumulation of T. fermentans were inhibited by [Ch][OAc] and the biomass, lipid content, and lipid yield in the presence of 60 mM [Ch][OAc] were reduced by 36.5, 17.2, and 47.1%, respectively, compared with those of the control (Fig. 1a–c). Similar phenomenon was also observed in studying the effect of [Emim][OAc] on lipid production by R. toruloides, and the inhibition of [Emim][OAc] on cell growth and lipid accumulation was attributed to the assimilation of acetate which led to a rapid alkaline-pH shift [13].Fig. 1

Bottom Line: Despite the reduction in lipid content, the lipid production by T. fermentans was improved in the presence of low concentrations of [Ch][Lys] (≤30 mM) and [Ch][Ser] (≤20 mM) due to the remarkable increase of biomass.However, the anions of [Ch][Lys] and [Ch][Ser] could be assimilated as nitrogen source by T. fermentans and the reduced C/N ratio accounts for the inhibition of lipid accumulation, which could be alleviated by improving C/N ratio of medium.The anions of [Ch][Lys], [Ch][Ser] and [Ch][OAc] play an important role in affecting the cell growth and lipid accumulation of T. fermentans, and the inhibition of these three ILs on lipid production can be alleviated by careful fermentation condition control.

View Article: PubMed Central - PubMed

Affiliation: School of Biosciences and Bioengineering, Guangzhou Higher Education Mega Centre, South China University of Technology, 382 East Waihuan Rd., Panyu District, Guangzhou, 510640 China.

ABSTRACT

Background: Microbial lipid is a potential raw material for large-scale biodiesel production and lignocellulosic hydrolysate has been considered as promising low-cost substrate for lipid fermentation. Lignocellulosic biomass needs to be pretreated before enzymatic hydrolysis, and biocompatible cholinium ionic liquids (ILs) have been demonstrated to be highly efficient for pretreatment. However, the impact of these ILs residues in hydrolysates on downstream biotransformation remains unknown. Therefore, the influence of three typical cholinium ILs on the lipid production by Trichosporon fermentans was first investigated.

Results: The cell growth of T. fermentans was stimulated in the presence of cholinium lysine ([Ch][Lys]) and cholinium serine ([Ch][Ser]), while the lipid accumulation was inhibited by [Ch][Lys]) and [Ch][Ser]. Both cell growth and lipid accumulation of T. fermentans were inhibited in the presence of cholinium acetate ([Ch][OAc]). Despite the reduction in lipid content, the lipid production by T. fermentans was improved in the presence of low concentrations of [Ch][Lys] (≤30 mM) and [Ch][Ser] (≤20 mM) due to the remarkable increase of biomass. It was found that cholinium cation had minor influence on lipid production. However, the anions of [Ch][Lys] and [Ch][Ser] could be assimilated as nitrogen source by T. fermentans and the reduced C/N ratio accounts for the inhibition of lipid accumulation, which could be alleviated by improving C/N ratio of medium. In addition, the anion of [Ch][OAc] could be metabolized by T. fermentans, leading to a rapid alkaline-pH shift and strong inhibition of lipid production. And this inhibitory effect on lipid production could be significantly reduced by controlling culture pH.

Conclusions: The anions of [Ch][Lys], [Ch][Ser] and [Ch][OAc] play an important role in affecting the cell growth and lipid accumulation of T. fermentans, and the inhibition of these three ILs on lipid production can be alleviated by careful fermentation condition control. Hence, T. fermentans is a promising strain for microbial lipid production from cholinium ILs-pretreated lignocellulosic hydrolysates.

No MeSH data available.


Related in: MedlinePlus