Objective  PropagatingStropharia rugosoannulata in liquid culture medium was studied.

  Methods  S. rugosoannulata No. 8 was cultivated in experimental media to determine the mycelial biomass increase in a single factor and orthogonal test L₉(3⁴) for formulation and culture conditions optimization. Mycelial biomass, reducing sugars, and amino nitrogen content as well as the extracellular enzyme activities of carboxymethyl cellulase, amylase, acid protease, and laccase of the culture were monitored to determine cultivation end point. Average full-bag filling time was used as indicator for the inoculation amount, substrate particle size, and carbon-to-nitrogen ratio in a maximized reproduction and yield.

  Results  The optimized liquid culture medium was formulated with 20 g·L⁻¹ glucose, 30 g·L⁻¹ wheat flour, 0.75 g·L⁻¹ yeast powder, 1.00 g·L⁻¹ potassium dihydrogen phosphate, and 0.50 g·L⁻¹ magnesium sulfate at an initial pH of 5. On the 8th day of culture, the mycelial biomass reached a maximum at 1.66 g·h mL⁻¹. As the mycelia grew, the reducing sugar in the medium decreased from 12.23 mg·mL⁻¹ to 1.38 mg·mL⁻¹ and the amino nitrogen from 0.09 mg·L⁻¹ to 0.06 mg·L⁻¹ during the culture process. The activities of carboxymethyl cellulase and amylase were the highest on the 4th day with the activities of 6.49 U and 5.16 U, respectively. The activity of acid protease peaked at 1.80 U on the 2nd day; and that of laccase, at 1.63 U on the 6th day. The inoculum production was best carried out with an inoculation of 15 mL, a coarse-to-fine ratio of 7∶3 on the substrate particle size, and a carbon-to-nitrogen ratio of 50∶1.

  Conclusion  Since the viability of the mushroom propagation correlated with some of the physiological and biochemical indicators of the liquid medium, 7 d was determined to be the peak for the cultivation. For filling a hyphal bag, 23.7d of culture was required, which was 2.7d shorter than what needed without the optimization. The results provided the basis for the development of a scale-up industrial operation.