Renewable Energy Global Innovations features: Promotion of microalgal growth by co-culturing with Cellvibrio pealriver using xylan as feedstock

Significance Statement

Microalgal biodiesel is a promising biofuel with potential for sustainable fuel production. To promote biomass and lipid production, a series of strategies are being developed, such as: mixotrophic and heterotrophic growths of microalgae on organic carbon sources or industrial wastes, or cultivation coupled with wastewater treatment plants.

Xylose is the major components among hemicellulose and rich in corn and rice straws, sugarcane bagasse, and grass. However, xylose is unable to directly use by wild type yeast or algae due to the xylose toxicity or deficient xylose transmembrane transport. Microalgal cultivations with xylose as carbon source have been reported in some xylose tolerant strains via mixotrophic or heterotrophic growths, or previous activation of glucose transporters.

In this paper, we constructed a bacterial-microalgal consortium for enhancing microalgal growth and lipid production. In the consortium, a xylanolytic bacterium Cellvibrio pealriver PR1 hydrolyzes xylan to xylose, which is then metabolized to some active substances through xylose isomerase or xylulokinase; the active substances are used for the growth and lipid production by microalgae. Based on the consortium, the mixotrophic growths of Chlorella sacchrarophila, Chlorella pyrenoidosa, Dunaliella sp. and Chlamydomonas reinhardtii were 2 to 3.3 folds higher than photoautotrophic growths, and equal to the mixotrophic growths with glucose as carbon source; the lipid production were 1 to 1.3 folds higher than the mixotrophic growths with glucose, and 1 to 1.5 folds higher than the photoautotrophic growths.

It was noted that the bacterial-microalgal consortium is a potential method to produce low-cost microalgal biodiesel by using cheap agricultural or industrial wastes.  

About The Author

Zhangzhang xie is currently a Ph.D. candidate in the major of Microbiology in School of Bioscience and Bioengineering at South China University of Technology. He focuses on the research of promoting the biomass and lipid production from microalgae.

About The Author

Weitie Lin is a professor in School of Bioscience and Bioengineering at South China University of Technology. He received his Ph.D. degree in fermentation engineering from South China University of Technology in 1991. He is the first Ph.D. candidate in the major of fermentation engineering in China. His present research interests include: 1) fermentation engineering in microbiology and food science; 2) application of microbiology for agricultural waste treatment and recycle; 3) microbial ecology in natural environment, agricultural and industrial wastewater treatment systems.  

About The Author

Jianfei Luo is an associate professor in School of Bioscience and Bioengineering at South China University of Technology. He received his Ph.D. degree in fermentation engineering from South China University of Technology in 2011. His present research interests focus on the microbial interaction with microorganism and environment during food fermentation, environmental bioremediation, and bioenergy development.  

Journal Reference

Bioresour Technol 2016 Jan 23;200:1050-4. Epub 2015 Oct 23.

Zhangzhang Xie, Weitie Lin, Jianfei Luo

Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510006, PR China.

Abstract

In this work, a Cellvibrio pealriver-microalga co-cultivation mode was used to promote the growths of four microalgae by using xylan as feedstock. After 12days of cultivation, the biomass concentrations of Chlorella sacchrarophila, Chlorella pyrenoidosa and Chlamydomonas reinhardtii in co-cultivation were equal to those in mixotrophic growth on glucose, and the Dunaliella was about 1.6-fold higher than that on glucose.

The comparative transcriptomes analysis demonstrated that the xylose and xylan hydrolysates were catalyzed to some active substrates by C. pealriver via some functional enzymes; these active substrates are possibly responsible for the promotion of microalgal growth. This C. pealriver-microalga co-cultivation mode is a potential method to produce low-cost microalgal biodiesel by using hemicellulose as feedstock.

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