Establishing microbial communities to promote the growth of Pleurotus ostreatus through a top-down approach is hindered by the dominance of antagonistic interactions

Summary

Researchers studied how to improve oyster mushroom growth by adding helpful bacteria to the growing substrate. They found that most bacteria actually compete with the mushrooms and slow their growth, making it difficult to create beneficial microbial communities using standard enrichment methods. Only one type of bacterium (Brevundimonas) showed neutral interaction with the mushrooms, while several others actively inhibited growth. The study suggests that future approaches should integrate the mushroom into the enrichment process from the beginning rather than trying to add pre-selected microbial communities afterward.

Background

Pleurotus ostreatus is a biotechnologically relevant mushroom used in lignocellulosic biomass pretreatment for bioenergy and bioproduct production. Establishing beneficial microbial communities with P. ostreatus is complicated by variable antagonistic interactions and competition for carbon sources in lignocellulosic substrates.

Objective

This study investigated whether microbial community compatibility with P. ostreatus is improved in conditions favoring saprophyte metabolism and enhanced by combining recalcitrant and labile carbon sources. The research aimed to identify beneficial bacterial traits and determine optimal enrichment strategies for mushroom growth promotion.

Results

Co-inoculation of lignocellulosic substrate with microbial enrichment generally reduced P. ostreatus growth compared to fungal monoculture. Enrichments relying solely on recalcitrant carbon promoted antagonistic communities inhibiting growth, while those with labile carbon substrates were more conducive to compatibility. Only Brevundimonas sp. displayed neutral interaction with P. ostreatus, while Pseudomonas, Asticcacaulis, Shinella, and Rhizobium species showed antagonistic effects.

Conclusion

Carbon degradation functions are not primary drivers of beneficial microbial communities for P. ostreatus growth. Top-down enrichment approaches are hindered by antagonistic interactions, suggesting that directed enrichment cultures integrating the mushroom as a selective agent from the earliest stage would promote more beneficial interactions and support sustainable lignocellulosic biomass bioprocessing.
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