Digital Analysis of Mycelium Growth and Mycelium Density <i>In Vitro</i> of <i>Pleurotus ostreatus</i> with Submerged Fermentation as Substrate Treatment

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 <i>in vitro</i> 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 <i>P. ostreatus</i> 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 <i>P. ostreatus</i> mycelium, the naturally-present microorganisms in the substrate appear to have at least neutral effects, enabling mycelial growth.