Interspecific interactions in dual-species biofilms of soil bacteria: effects of fertilization practices

Xiaojie Sun, Peng Cai, Søren Johannes Sørensen, Monika Mortimer, Chunhui Gao, Qiaoyun Huang, Yiming Wang, Xiangui Lin, Yichao Wu, Di Zhu, Ruirui Chen

Abstract

Purpose: Bacterial cooperation and competition in biofilms are being recognized as important factors in regulating structure and function of microbial communities. However, knowledge about soil bacterial interactions in biofilms and how these may be influenced by different fertilization practices is still limited. This study aims to investigate interspecific interactions in biofilms and the effects of fertilization practices on these interactions. Materials and methods: We assessed bacterial interactions according to a classification criterion proposed recently via comparing biomass of single-species biofilms with dual-species biofilms. Biofilm biomass was measured by crystal violet staining using the modified Calgary biofilm device. Results and discussion: Increased biofilm formation was detected in 67% of co-cultures that were composed of strains isolated from unfertilized soil, indicating a high prevalence of cooperation among the strains in natural soil. In contrast, decreased biofilm formation was detected in 74% of co-cultures that contained strains isolated from soil receiving chemical fertilizer. Interestingly, combinations of bacterial isolates from soils amended with chemical fertilizer in combination with composted chicken manure or mushroom residues showed higher level of synergism and biofilm induction in dual-species biofilms than the strains from chemically fertilized soils, suggesting integrated fertilization with composted chicken manure or mushroom residues may help maintain the native microbial interaction network dominated by synergistic interactions. Conclusions: Together, these findings indicate that social interactions, required for biofilm formation, among soil bacteria are affected by fertilization practices. Cooperation is dominant in dual-species biofilms in unfertilized soil. Organic manure could mitigate the negative impacts on bacterial social interactions caused by chemical fertilizers.

Original languageEnglish
JournalJournal of Soils and Sediments
Number of pages8
ISSN1439-0108
DOIs
Publication statusPublished - 1 Mar 2020

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