Mycelial cultivation of Phellinus linteus using cheese-processing waste and optimization of bioconversion conditions

Abstract

A medicinal mushroom, Phellinus linteus, was successfully cultivated using a cheese-processing waste, whey, and the optimal bioconversion conditions for the maximum mycelial growth rate was also estimated through solid-state cultivation experiments. Response surface analysis with a face-centered design (center point replication = 5) was applied to statistically approximate the simultaneous effects of the three variables, i. e., substrate concentration (10-30 g lactose l-1), temperature (20-30°C), and pH (4-6), on the mycelial growth rate of P. linteus. The following is a partial cubic model where η is the mycelial growth rate (Kr) and xk is the corresponding variable term (k = substrate concentration, temperature, and pH in order): η = -23.8 + 8.67 × 10-2x1 + 1.48x2 + 1.77x3 + 8.00 × 10-4x1x2 + 7.25 × 10-2x1x3 + 5.13 × 10-2x2x3 -1.28 × 10-2x1 2 -3.18 × 10-2x2 2. -2.64 × 10-1x3 2 -3.28 × 10-3x1x2x3 + 4.68 × 10-4x1 2x2. The produced response surface model proved to be significant (r2 > 0.99, P-value <0.0001, coefficient of variation <5%) to describe the explored space. Temperature was found to be the most significant factor of dominant effects on the mycelial growth rate, and other variables such as temperature2, pH, pH2, and (substrate concentration2 × temperature) also showed significant effects on the model output. The maximum mycelial growth rate was predicted to be 2.80 mm d-1 at 29.7 g lactose l-1, 26.2°C, and pH 5. Our results proved a good potential of whey to serve as an alternative growth medium for cultivating P. linteus mycelia. This may provide another potential for managing this nutrient-rich waste in a cost-effective way.