Optimization of culture conditions, nutritional characterization, toxicity and teratogenecity of Lentinus tigrinus-A newly recorded domesticated wild mushroom in the Philippines

Lentinus tigrinus is a wood-rotting mushroom that is usually found growing on fallen logs during the onset and middle part of the rainy season where moisture is abundant. The study determined the optimum culture conditions of basidiospore germination, secondary mycelial growth and fruiting body performance of L. tigrinus with special reference to the influence of nutritional (different indigenous culture media) and physical (pH, aeration, illumination and temperature) factors. The proximate nutritional attributes of the air-dried stipe and pileus of fruiting bodies harvested in the optimum substrate were analyzed. The lyophilized extract of L. tigrinus was tested in female ICR mice following the single dose toxicity test by oral gavage for its biosafety. Lethal and sublethal (teratogenic) effects were examined in treated developing zebrafish (Danio rerio) embryos. Results of the study revealed that basidiospores of L. tigrinus germinated efficiently in a submerged culture with potato sucrose broth (pH 7.5) incubated in a lighted air-conditioned room (23˚C) with a mean of 91.33% after 10h of incubation. Its secondary mycelia grew best on solid medium with coconut water gulaman (local crude agar) with a pH range of 7.0-8.0, incubated in either sealed or unsealed, dark and room temperature (32˚C) condition. Among the evaluated granular spawn material, palay seeds (rice grain with husk) yielded a very luxuriant mycelial growth with the shortest incubation period of 5 days. The highest biological efficiency of 15.93% was significantly (p˂0.05) recorded in 2 parts of sawdust + 8 parts of rice straw substrate formulation. This formulation produced the highest mean number of fruiting bodies of 9.6 with 29.75mm stipe length and 58.34mm pileus diameter. Both air-dried pileus and stipe hold promising nutritional contents. The pileus had higher amount of crude protein (25.90%), crude fat (2.12%), ash (7.41%) and moisture (12.20%), while the stipe had higher amount of carbohydrates (43.02%) and crude fiber (24.74). Acute single oral toxicity test in mice revealed that L. tigrinus is toxicologically safe. However, treated embryos showed both lethal and teratogenic effects such as underdeveloped head, unformed head and tail, perverted tail, serious pericardial edema and hook-like tail. Altogether, Lentinus tigrinus is an addition to the newly recorded and successfully domesticated wild nutritious mushroom. However, results suggest that it is not recommended for pregnant women