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Chinese Journal of Applied Ecology ›› 2020, Vol. 31 ›› Issue (2): 625-633.doi: 10.13287/j.1001-9332.202002.034

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Symbiotic bacteria facilitate algal growth and oil biosynthesis in Scenedesmus obliquus

DUAN Lu-lu, CHEN Wei-lan, ZHANG Jing-jie, MA Hao-tian, JI Chun-li, CUI Hong-li, WANG Ji-ping, LI Run-zhi*   

  1. Institute of Molecular Agriculture and Bioenergy, Shanxi Agricultural University, Taigu 030801, Shanxi, China
  • Received:2019-06-21 Online:2020-02-15 Published:2020-02-15
  • Contact: * E-mail: rli2001@126.com
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (31201266, 31401430, 31902344), the Ministry of Agriculture “948” Project (2014-Z39), the Shanxi Province Key Project of Coal-based Science and Technology (FT-2014-01), the Shanxi Scholarship Fund (2015-064), the Key Project of the Key Research and Development Program of Shanxi Province (201603D312005), and the Key Research and Development (R&D) General Progam of Shanxi Province (201803D31063).

Abstract: We isolated bacteria from the phycosphere of Scenedesmus obliques and sequenced 16S rDNAs to establish algae-bacterial co-culture systems. Further, we examined effects of the bacteria on algal growth, and parameters associated with physio-biochemical and oil-producing characteristics of S. obliquus. Seven bacterial strains were isolated, including Micrococcus (strains 1-1, 1-2 and 1-3), Pseudomonas sp. (strains 2-1 and 2-2), Exiguobacterium (strain-3) and Staphylococcus sp. (strain-4). Among them, two bacteria (strain 1-2 and strain 2-1) were characterized as the dominant growth-promoting bacterial strains, which significantly increased algal growth, pigment production, and oil enrichment. After eight days cultivation under microalgal-bacterial (strain 1-2) symbiotic systemat at an initial ratio of 1:10, biomass of S. obliquus was 4.27 g·L-1, about 46.0% higher than that of the control. The contents of chlorophyll a, chlorophyll b and carotenoids were increased by 12.1%, 16.7% and 25.0%, respectively. Oil content was increased by 14.0% and reached to 25.7%, and the oleic acid content was significantly higher than that of the control and up to 16.4%. When co-cultured with Pseudomonas sp. (strain 2-1) for eight days at an initial ratio of 1:5, algal biomass, chlorophyll a, chlorophyll b and carotenoids contents were higher than that of the control by 47.9%, 16.0%, 17.5% and 19.9%, respectively. The total oil (27.1%) and oleic acid (18.2%) contents were increased by 20.4% and 64.0%, respectively. We concluded that Micrococcus (strain 1-2) and Pseudomonas sp. (strain 2-1) could significantly promote algal growth and increase oil production by their beneficial interaction with S. obliques, which could be potentially used in commercial production of S. obliques.