Obtaining Phlebiopsis gigantea Oidia Using Liquid- and Solid-Surface Cultivation Processes

Fungal spores are the main active ingredients in fungal preparations. In this study, we evaluated vegetative spore (oidia) production of the Latvian isolate of Phlebiopsis gigantea PG 182 using liquid-surface (LSF) and solid-state (SSF) fermentation processes in the 450 mL and 700 mL jars, respectively. The effects of medium depth (0.5 or 0.7 cm), malt extract (ME) syrup concentration (25, 50, and 75 g/L) and duration time of cultivation (7, 14, 21 and 28 days) on oidia production and partly on mycelium biomass yield were evaluated in the LSF experiments. The highest spore yields (0.88 ± 0.22) × 107 and (1.10 ± 0.31) × 107 (95% CI) (oidia/g liquid medium) were achieved on day 28 in the LSF process using a medium depth of 0.5 cm and ME concentrations of 25 and 50 g/L, respectively. While in the SSF process, pine sawdust enrichment with wheat bran (0, 5, 10, 15, and 25%) and cultivation time (14, 21 and 28 days) were evaluated under conditions of 8 cm substrate depth. The most promising result was obtained on day 28 with 10% bran supplementation, reaching (24.73 ± 5.09) × 107 (95% CI) (oidia/g solid medium), which is 1.45 and 3.17 times more than after 21 and 14 days of cultivation, respectively. Our findings indicate that SSF with a 10% wheat bran additive produces superior spore yields for P. gigantea isolate PG 182, exceeding benchmarks set by comparable research. Potential for further improvement remains by optimizing the wheat bran (WB)-to-substrate ratio and refining the thermal processing of the solid substrate.