摘要
Metarhizium anisopliae as an essential entomopathogenic fungus has been known to produce destruxins （a kind of cyclo-peptidic mycotoxins） and blastospores in submerged culture. Blastospores and destruxins are candidates for in- secticides, but the relations of both productions and the impact factors are unclear yet. In this study, we investigated the effects of inoculums, rotation, dissolved oxygen （DO） on the productions of blastospores and destruxins A and B （DA and DB） in submerged culture of M. anisopliae strain MaQ01. The results indicated that DO levels were regulated by inoculum amounts and rotation speeds, meanwhile, the productions of DA, DB and blastospores were also closely influenced by those factors. Totally, when DO value was more than 40%, the higher productions of destruxins and blastospores were achieved, by contrast, lower than 40% of DO values resulted in lower productions. The regression analysis suggested that the productions of DA, DB and blastospores were positively correlated with the DO levels. Meanwhile, the positive correlations between the productions of DA or DB and blastospores were also found. Briefly, when the rotation is 150 r min-1 and the inoculum is 1.0xl06 spore mL-1, the DA, DB and blastospores achieved the best production of 61.81 mg mL-1, 24.74 mg mL-1 and 5.73x 108 spore mL-1, respectively. In addition, the pathogenicities of blastospores and conidia against Plutella xylostella were bioassayed. The higher mortalities of P. xylostella were totally recorded in blastospore treatments than in conidia treatments, especially in lower dosages and earlier periods. Our research will give some new insights to production of destruxins and blastospores by using M. anisopliae.
Metarhizium anisopliae as an essential entomopathogenic fungus has been known to produce destruxins （a kind of cyclo-peptidic mycotoxins） and blastospores in submerged culture. Blastospores and destruxins are candidates for in- secticides, but the relations of both productions and the impact factors are unclear yet. In this study, we investigated the effects of inoculums, rotation, dissolved oxygen （DO） on the productions of blastospores and destruxins A and B （DA and DB） in submerged culture of M. anisopliae strain MaQ01. The results indicated that DO levels were regulated by inoculum amounts and rotation speeds, meanwhile, the productions of DA, DB and blastospores were also closely influenced by those factors. Totally, when DO value was more than 40%, the higher productions of destruxins and blastospores were achieved, by contrast, lower than 40% of DO values resulted in lower productions. The regression analysis suggested that the productions of DA, DB and blastospores were positively correlated with the DO levels. Meanwhile, the positive correlations between the productions of DA or DB and blastospores were also found. Briefly, when the rotation is 150 r min-1 and the inoculum is 1.0xl06 spore mL-1, the DA, DB and blastospores achieved the best production of 61.81 mg mL-1, 24.74 mg mL-1 and 5.73x 108 spore mL-1, respectively. In addition, the pathogenicities of blastospores and conidia against Plutella xylostella were bioassayed. The higher mortalities of P. xylostella were totally recorded in blastospore treatments than in conidia treatments, especially in lower dosages and earlier periods. Our research will give some new insights to production of destruxins and blastospores by using M. anisopliae.
基金
supported by the Special Fund for Forest Scientific Research in the Public Welfare (201304408)
the Open Fund of Key Laboratory of Forest Diseases and Insect Pests in Guangdong Province, China
