2. Academic Validation
  3. Inoculating indoleacetic acid bacteria promotes the enrichment of halotolerant bacteria during secondary fermentation of composting

Inoculating indoleacetic acid bacteria promotes the enrichment of halotolerant bacteria during secondary fermentation of composting

  • J Environ Manage. 2022 Nov 15:322:116021. doi: 10.1016/j.jenvman.2022.116021.
Yanlin Li 1,  Mingdian Zhou 1,  Chunxing Li 2,  Xiaofang Pan 3,  Nan Lv 4,  Zhilong Ye 3,  Gefu Zhu 5,  Quanbao Zhao 6,  Guanjing Cai 7
Affiliations

Affiliations

  • 1 Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
  • 2 State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023, China.
  • 3 Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
  • 4 State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China.
  • 5 School of Environment and Nature Resources, Renmin University of China, Beijing, 100872, China; Key Laboratory of Energy Resource Utilization from Agriculture Residue, Ministry of Agriculture and Rural Affairs, China. Electronic address: zgf@ruc.edu.cn.
  • 6 Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China. Electronic address: qbzhao@iue.ac.cn.
  • 7 Biology Department and Institute of Marine Sciences, College of Science, And Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou, 515063, China. Electronic address: gjcai@stu.edu.cn.
PMID: 36067675 DOI: 10.1016/j.jenvman.2022.116021
Abstract

The secondary fermentation stage is critical for stabilizing composting products and producing various secondary metabolites. However, the low metabolic rate of mesophilic bacteria is regarded as the rate-limiting stage in composting process. In present study, two indoleacetic acid (IAA)-producing bacteria (Bacillus safensis 33C and Corynebacterium stationis subsp. safensis 29B) were inoculated to strengthen the secondary fermentation stage to improve the plant-growth promoting potential of composting products. The results showed that the addition of IAA-producing bacteria promoted the assimilation of soluble salt, the condensation and aromatization of humus, and the accumulation of dissolved organic nitrogen (DON) and dissolved organic carbon (DOC). The bioaugmentation strategy also enabled faster microbial community succession during the medium-late phase of secondary fermentation. However, the colonization of Bacillus and Corynebacterium could not explain the disproportionate increase of IAA yield, which reached up to 5.6 times compared to the control group. Deeper analysis combined with physicochemical properties and microbial community structure suggested that IAA-producing bacteria might induce the increase of salinity, which enriched halotolerant bacteria capable of producing IAA, such as Halomonas, Brachybacterium and Flavobacterium. In addition, the results also proved that it was necessary to shorten secondary fermentation time to avoid IAA degradation without affecting composting maturity. In summary, enhancing secondary fermentation of composting via adding proper IAA-producing bacteria is an efficient strategy for upgrading the quality of organic fertilizer.

Keywords

Aerobic compost; Halotolerant bacteria; Indoleacetic acid; Indoleacetic acid-producing bacteria; Secondary fermentation.

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