Multifunctional
microbial strains for spent mushroom substrate treatment: from Cellulase production
to plant growth promotion
Ngoc An Nguyen, Tan Viet Pham, Dung Vo Anh Truong, Hanh Thi-Dieu Nguyen
Res. J. Biotech.; Vol. 20(5); 142-151;
doi: https://doi.org/10.25303/205rjbt1420151; (2025)
Abstract
This study investigated the potential of cellulose-degrading microorganisms for
treating agricultural by-products, specifically spent mushroom substrate (SMS).
From a pile of SMS, 48 thermotolerant microbes were isolated, comprising of 24 bacterial
strains, 20 actinomycete strains and 4 mold strains. Following cellulase production
and co-culture compatibility screening, seven strains were selected for further
analysis. Phylogenetic analysis based on 16S rRNA and ITS sequences identified three
strains (DVK16, DVK27, DVK33) as Bacillus spp., two (DXK61, DXK98) as Streptomyces
spp. and two (DM1, DM2) as Rasamsonia spp.
Notably, the two strains Streptomyces sp. DXK98 and Rasamsonia sp. DM1 exhibited
strong indole-3-acetic acid biosynthesis, while Bacillus sp. DVK33 demonstrated
phosphorus solubilizing ability, suggesting potential plant growth-promoting properties.
Treatment of SMS with 10% microbial inoculant resulted in a decreased C:N ratio
and increased total nitrogen, potassium and phosphorus content. Furthermore, plants
grown on treated SMS exhibited improved height and root length. These findings suggest
that applying these microbes in SMS treatment not only aids in environmental protection
but also offers economic benefits through the reuse of SMS in crop production.
