Changes and recovery of soil bacterial communities influenced by biological soil disinfestation as compared with chloropicrin-treatment.

Subrata Mowlick,Toshiaki Takehara,Nobuo Kaku,Katsuji Ueki,Atsuko Ueki,Takashi Inoue

doi:10.1186/2191-0855-3-46

Subrata Mowlick, Toshiaki Takehara + Show 4 more

Open Access

https://doi.org/10.1186/2191-0855-3-46

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Abstract

Soil bacterial composition, as influenced by biological soil disinfestation (BSD) associated with biomass incorporation was investigated to observe the effects of the treatment on the changes and recovery of the microbial community in a commercial greenhouse setting. Chloropicrin (CP) was also used for soil disinfestation to compare with the effects of BSD. The fusarium wilt disease incidence of spinach cultivated in the BSD- and CP-treated plots was reduced as compared with that in the untreated control plots, showing effectiveness of both methods to suppress the disease. The clone library analyses based on 16S rRNA gene sequences showed that members of the Firmicutes became dominant in the soil bacterial community after the BSD-treatment. Clone groups related to the species in the class Clostridia, such as Clostridium saccharobutylicum, Clostridium tetanomorphum, Clostridium cylindrosporum, Oxobacter pfennigii, etc., as well as Bacillus niacini in the class Bacilli were recognized as the most dominant members in the community. For the CP-treated soil, clones affiliated with the Bacilli related to acid-tolerant or thermophilic bacteria such as Tuberibacillus calidus, Sporolactobacillus laevolacticus, Pullulanibacillus naganoensis, Alicyclobacillus pomorum, etc. were detected as the major groups. The clone library analysis for the soil samples collected after spinach cultivation revealed that most of bacterial groups present in the original soil belonging to the phyla Proteobacteria, Acidobacteria, Bacteroidetes, Gemmatimonadetes, Planctomycetes, TM7, etc. were recovered in the BSD-treated soil. For the CP-treated soil, the recovery of the bacterial groups belonging to the above phyla was also noted, but some major clone groups recognized in the original soil did not recover fully.

Highlights

Soil fumigation is an effective method to control soilborne plant pathogens and soil is generally fumigated with chemicals before planting high-value cash crops
In our previous studies, using model experiments of biological soil disinfestation (BSD) with wheat bran or Brassica juncea and Avena strigosa plants as biomass sources, we successfully controlled pathogen populations (Fusarium oxysporum f. sp. lycopersici, wilt pathogen of tomato and F. oxysporum f. sp. spinacea, wilt pathogen of spinach) incorporated into soil (Mowlick et al 2012a, b)
We analyzed the bacterial communities in the BSD-treated soil samples by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and clone library analysis based on the 16S rRNA gene sequences and it was shown that the community structures changed drastically in response to the treatments

Summary

Introduction

Soil fumigation is an effective method to control soilborne plant pathogens and soil is generally fumigated with chemicals before planting high-value cash crops. In our previous studies, using model experiments of BSD with wheat bran or Brassica juncea and Avena strigosa plants as biomass sources, we successfully controlled pathogen populations We analyzed the bacterial communities in the BSD-treated soil samples by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and clone library analysis based on the 16S rRNA gene sequences and it was shown that the community structures changed drastically in response to the treatments. It is important for us to prove the efficacy of BSD for controlling soil-borne disease under field conditions (in practice) and to know the changes and recovery of the bacterial community structures in soil as affected by the treatments

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