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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 C/N ratio on the lipid production by T. fermentans in the presence of [Ch][Lys] or [Ch][Ser]. a Cell growth of T. fermentans in the medium containing 30 mM lysine or serine as sole nitrogen source. b Cell growth and lipid accumulation of T. fermentans in the media containing 30 mM [Ch][Lys] or [Ch][Ser] but with different C/N ratios. The results are mean of two experiments, and error bars represent standard deviations from mean value.
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Fig4: Effect of C/N ratio on the lipid production by T. fermentans in the presence of [Ch][Lys] or [Ch][Ser]. a Cell growth of T. fermentans in the medium containing 30 mM lysine or serine as sole nitrogen source. b Cell growth and lipid accumulation of T. fermentans in the media containing 30 mM [Ch][Lys] or [Ch][Ser] but with different C/N ratios. The results are mean of two experiments, and error bars represent standard deviations from mean value.

Mentions: Previous reports showed that amino acids could be used as nitrogen source by yeasts [21, 22] and the above results demonstrated that the anions of [Ch][Lys] and [Ch][Ser] were assimilated by T. fermentans. To test whether these two anions can be utilized as nitrogen source by T. fermentans, cells were cultivated in the medium containing 30 mM lysine or serine as sole nitrogen source for 4 days and the OD600 values were recorded. As depicted in Fig. 4a, the OD600 values of the control (medium without any nitrogen source) remained almost unchanged during cultivation. In contrast, the OD600 values of culture broth supplied with 30 mM lysine or serine increased with time and reached its maximum of 25.04 or 20.26 at 67 h. After that, a slight decline in OD600 values was observed, indicating that lysine and serine were indeed used as nitrogen source by T. fermentans.Fig. 4


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 C/N ratio on the lipid production by T. fermentans in the presence of [Ch][Lys] or [Ch][Ser]. a Cell growth of T. fermentans in the medium containing 30 mM lysine or serine as sole nitrogen source. b Cell growth and lipid accumulation of T. fermentans in the media containing 30 mM [Ch][Lys] or [Ch][Ser] but with different C/N ratios. 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

Fig4: Effect of C/N ratio on the lipid production by T. fermentans in the presence of [Ch][Lys] or [Ch][Ser]. a Cell growth of T. fermentans in the medium containing 30 mM lysine or serine as sole nitrogen source. b Cell growth and lipid accumulation of T. fermentans in the media containing 30 mM [Ch][Lys] or [Ch][Ser] but with different C/N ratios. The results are mean of two experiments, and error bars represent standard deviations from mean value.
Mentions: Previous reports showed that amino acids could be used as nitrogen source by yeasts [21, 22] and the above results demonstrated that the anions of [Ch][Lys] and [Ch][Ser] were assimilated by T. fermentans. To test whether these two anions can be utilized as nitrogen source by T. fermentans, cells were cultivated in the medium containing 30 mM lysine or serine as sole nitrogen source for 4 days and the OD600 values were recorded. As depicted in Fig. 4a, the OD600 values of the control (medium without any nitrogen source) remained almost unchanged during cultivation. In contrast, the OD600 values of culture broth supplied with 30 mM lysine or serine increased with time and reached its maximum of 25.04 or 20.26 at 67 h. After that, a slight decline in OD600 values was observed, indicating that lysine and serine were indeed used as nitrogen source by T. fermentans.Fig. 4

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