Identification and physiological properties of a Nigerian strain of Volvariella sp. isolated from oil palm waste

Over the years several species of edible mushrooms have been collected for consumption from different agro-wastes in Nigeria. Identification of most of these mushrooms was often by morphological descriptive methods. This study reports the morphological study, physiological study and identification of a Nigerian wild strain of Volvariella sp. (VNW) isolated from discarded oil palm waste and three Indian commercial strains V11, V245 and V247 of V. volvacea. Effect of incubation temperatures and medium pH was investigated. Molecular characterization of the strains was carried out using ITS-1 and ITS-4 primers. Results obtained showed close similarities of the Nigerian strain to the Indian strains with few morphological variations in colour, shape and appearance. Growth was observed at temperature range of 20-40 °C and pH range of 4.0-8.0 for all strains with optimum mycelia extension at 35 °C and pH 6.0. VNW recorded a significantly higher (p ≤ 0.05) mycelia extension rate at 35 °C (25.20 ± 1.80 mm/day) and pH 6.0 (40.20 ± 0.34 mm/day). Highest biomass yield was observed at pH 6.0 with V11 recording a significantly (p ≤ 0.05) higher yield (1.74 ± 0.07 g/100 mL). Increasing percentage (w/v) of CaSO₄·H₂O increased biomass yield of all the strains. NJ phylogenetic tree showed the Nigerian and Indian strains in the same cluster indicating evolutionary closeness than with other species of Volvariella from GenBank in a separate cluster even though they share a common ancestor. This successfully proves the identity of a Nigerian strain of Volvariella sp. VNW from oil palm waste as V. volvacea with GenBank accession number KC894923.