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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

Effect of [Ch]Cl on the cell growth and lipid accumulation of T. fermentans. The results are mean of two experiments, and error bars represent standard deviations from mean value.
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Fig2: Effect of [Ch]Cl on the cell growth and lipid accumulation of T. fermentans. The results are mean of two experiments, and error bars represent standard deviations from mean value.

Mentions: To test whether the anions of [Ch][Lys], [Ch][Ser], and [Ch][OAc] could be assimilated by T. fermentans, cells were cultured in the media containing 30 mM various ILs and 1 mL sample was taken daily to measure the anion concentration of the ILs. As can be seen in Fig. 1d, the concentrations of the three anions decreased with the increase of fermentation time and all the anions could be used up. The consumption rate of the anions followed the order: [Ser]− > [OAc]− > [Lys]−. It is known that both the cation and the anion of ILs can contribute to their toxicity [11, 12]. Hence, to understand the influence of cholinium cation on lipid production by T. fermentans, various concentrations of choline chloride ([Ch]Cl) were supplemented into the fermentation medium. As shown in Fig. 2, when [Ch]Cl was added at 10 mM, the biomass and lipid content were comparable to those of the control (14.9 vs. 14.2 g/L, 58.7 vs. 59.9%). Even in the presence of 60 mM [Ch]Cl, the biomass and lipid content still reached 12.7 g/L and 58.6%, respectively, indicating that cholinium cation has minor effect on cell growth and lipid accumulation of T. fermentans.Fig. 2


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)

Effect of [Ch]Cl on the cell growth and lipid accumulation of T. fermentans. 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

Fig2: Effect of [Ch]Cl on the cell growth and lipid accumulation of T. fermentans. The results are mean of two experiments, and error bars represent standard deviations from mean value.
Mentions: To test whether the anions of [Ch][Lys], [Ch][Ser], and [Ch][OAc] could be assimilated by T. fermentans, cells were cultured in the media containing 30 mM various ILs and 1 mL sample was taken daily to measure the anion concentration of the ILs. As can be seen in Fig. 1d, the concentrations of the three anions decreased with the increase of fermentation time and all the anions could be used up. The consumption rate of the anions followed the order: [Ser]− > [OAc]− > [Lys]−. It is known that both the cation and the anion of ILs can contribute to their toxicity [11, 12]. Hence, to understand the influence of cholinium cation on lipid production by T. fermentans, various concentrations of choline chloride ([Ch]Cl) were supplemented into the fermentation medium. As shown in Fig. 2, when [Ch]Cl was added at 10 mM, the biomass and lipid content were comparable to those of the control (14.9 vs. 14.2 g/L, 58.7 vs. 59.9%). Even in the presence of 60 mM [Ch]Cl, the biomass and lipid content still reached 12.7 g/L and 58.6%, respectively, indicating that cholinium cation has minor effect on cell growth and lipid accumulation of T. fermentans.Fig. 2

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