Abstract
Edible mushroom cultivation often involves sterilizing the substrate, or a similar heat process like pasteurization, to facilitate mycelial colonization. Chemical treatments are an alternative approach that is also employed in some regions. Mycelial growth and density were analyzed in vitro by capturing daily photographs using a digital camera, with sterilized substrate serving as the control treatment. Our findings revealed that both fermented and sterilized substrates had similar growth patterns, although fermented treatment required a longer incubation time for full substrate colonization. Mycelium in fermented substrate had a denser structure compared to sterilized treatment, reflecting the interactions with the naturally-present microorganisms within the substrate. Conversely, mycelium in sterilized treatment exhibited faster substrate colonization times but had a less dense mycelial structure. Yeast and bacterial colonies were present throughout the fermentation process and 7 days after P. ostreatus mycelium inoculation, indicating active microbial communities during colonization. An initial decrease in CFU on the 3(rd) day, followed by an increase by the 7(th) day, suggests a shift toward anaerobic and facultative microorganisms due to oxygen depletion during fermentation. Mold colonies disappeared by the end of fermentation. Despite the complex interactions between yeast, bacteria, and P. ostreatus mycelium, the naturally-present microorganisms in the substrate appear to have at least neutral effects, enabling mycelial growth.