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

Thi My Pham, Xuan Dong Bui, Le Vu Khanh Trang, Thi Mai Le, Minh Ly Nguyen, Dang Mau Trinh, Nguyen Thi Dong Phuong, Kuan Shiong Khoo, Kit Wayne Chew, Pau Loke Show

Research output: Contribution to journalReview articlepeer-review

10 Scopus citations

Abstract

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.

Original languageBritish English
Pages (from-to)12-20
Number of pages9
JournalJournal of Biotechnology
Volume349
DOIs
StatePublished - 10 Apr 2022

Keywords

  • Azospirillum sp.
  • Chlorella vulgaris
  • Indole-3-acetic acid
  • Plant growth Rhizobacteria
  • Rhizosphere bacteria

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