Isolation of indole-3-acetic acid-producing Azospirillum brasilense from Vietnamese wet rice: Co-immobilization of isolate and microalgae as a sustainable biorefinery

• Published in: Journal of biotechnology Vol. 349; pp. 12 - 20
• Main Authors: Pham, Thi-My, Bui, Xuan Dong, Trang, Le Vu Khanh, Le, Thi-Mai, Nguyen, Minh Ly, Trinh, Dang-Mau, Phuong, Nguyen Thi Dong, Khoo, Kuan Shiong, Chew, Kit Wayne, Show, Pau Loke
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.04.2022
• Subjects: Azospirillum brasilense; Azospirillum sp; Chlorella vulgaris; Culture Media; Indole-3-acetic acid; Indoleacetic Acids; Microalgae; Nitrogen; Oryza; Plant growth Rhizobacteria; Rhizosphere bacteria; Vietnam; Vietnam; Rhizosphere bacteria; Indole-3-acetic acid; Plant growth Rhizobacteria; Chlorella vulgaris; Azospirillum sp
• ISSN: 0168-1656; 1873-4863
• DOI: 10.1016/j.jbiotec.2022.03.007

Production of indole-3-acetic acid (IAA) is well documented in various studies for the bacteria that inhabit the rhizosphere of plants, but with roots of wet rice, the outstandings have been not yet elucidated. This study began with the isolation of bacteria type strain Azospirillum sp. and developed the investigation to a screening of their ability in IAA production. This screening conducted a selection of only bacteria that was capable of the production of IAA with its content of over 25 µg. mL-1 for sequencing. Of 10 isolates only one resulted from the type strain Azospirillum brasilense (A. brasilense) with a similarity of 100%. Various factors that influence A. brasilense in biosynthesizing IAA such as temperature, pH, nitrogen presence and concentration of tryptophan in the culture medium were examined. The results indicated that the culture conditions were suitable for IAA biosynthesis at pH 6.5, 30 °C, culture media with nitrogen, and 0.1% trytophan. The next survey on the role of the immobilization of this bacteria with microalgae in alginate was highlighted to its support in microalgal growth. With the co-immobilization of bacteria and microalgae, the density of Chlorella vulgaris was significantly increased during 15-day culture, inducing 2.2 times of cell content in culture batch microalgae immobilized A. brasilense higher than that free-bacteria. [Display omitted] •Azospirillum sp. isolated from wet rice roots for production of indole-3-acetic acid (IAA).•Azospirillum brasilense isolated was exposed by different ability of IAA production.•pH system, temperature, tryptophan content and nitrogen media condition was evaluated.•Co-immobilization of isolated and microalgae increases the biomass productivity.•Growth of co-immobilize microalgae was 2.2 times compared to single culture.