Increase in yield of the straw mushroom (Vovariella volvacea) by supplement with Paenibacillus and Bacillus to the compost

Two bacterial isolates N10 and B2, isolated from the dry paper mulberry bark and from the air of indoor-farmed straw mushroom, respectively, were identified as Paenibacillus polymyxa and Bacillus subtilis by the conventional and Biolog method. The antagonism of these bacteria against plant pathogens and various kinds of edible mushrooms were investigated in vitro to determine its potential for compost application. P. polymyxa N10 inhibited plant pathogenic fungi, i.e., Fusarium oxysporum, Aspergillus niger, Alternaria sp., Sclerotium rolfsii and some edible mushrooms, i.e., Volvariella volvacea, Pleurotus ostreatus, P. abalonus, Lentinus squarrosulus and Auricularia auricular. P. polymyxa N10 was also inhibitive to commonly contaminated fungi found in compost, such as Trichoderma sp. and Monilia sp.. B. subtilis B2, on the other hand, did not inhibit the growth of V. volvacea but was antagonistic to almost all of tested fungi, except Trichoderma harzianum and Monilia sp.. Our preliminary test showed that yield of straw mushroom was increased by supplementation of cultured broth in compost in outdoor cultivation. They were grown in shaken nutrient broth at room temperature for 24 hrs (ca.1.5×10⁷ and 1.0×10⁷cfu/ml for P. polymyxa N10 and B. subtilis B2) and sprayed to mushroom compost at the rate of one liter per 4 m² area of 45 kg dry wt., then inoculated with straw mushroom spawn. Seven crops were done per year and each crop was accomplished by two indoor farms consisting of three replications each. Results of experiments of the first two years clearly indicated that mushroom yields from the bacterial supplemented compost were significantly higher than those of the control and nutrient broth treated one. On the third year, soybean milk or cow milk were used as growing medium for bacteria instead of nutrient broth to simplify the bacterial preparation technique and B. subtilis B2 was chosen as the only bacterial strain used for experiment based on experimental results of the previous two years. Overall results of the 3 year experiments strongly indicated that supplementation of P. polymyxa N10 and B. subtilis B2 to straw mushroom compost increased the mushroom yield over the non supplemented one.