Conversely, mycelial growth in bags with 15~45 mm holes was maintained at 2.15 to 3.22 mm/day from week 1 to 5. In bags with 5~20 mm holes, mycelial growth was highly positively correlated with carbon dioxide concentration (r = 0.85~0.99). Additionally, more active hyphal growth was associated with higher CO2 concentrations. Massive amounts of CO2 can stimulate mycelial growth [12], but the relationship between high CO2 contents by active hyphal growth and relatively less aeration in the bags was complex. Dikaryotic mycelium of L. edodes can be repressed under highly dissolved oxygen conditions [13]. At various CO2 levels, 0.03%, 12.5% and 25.0%, Rhizopus oligosporus grow best at the lowest 0.03% CO2