Effects of carbon concentration and carbon to nitrogen ratio on the growth and sporulation of several biocontrol fungi

Effects of carbon concentration and carbon to nitrogen (C:N) ratio on six biocontrol fungal strains are reported in this paper. All fungal strains had extensive growth on the media supplemented with 6–12 g l−1 carbon and C:N ratios from 10:1 to 80:1, and differed in nutrient requirements for sporulation. Except for the two strains of Paecilomyces lilacinus, all selected fungi attained the highest spore yields at a C:N ratio of 160:1 when the carbon concentration was 12 g l−1 for Metarhizium anisopliae SQZ-1-21, 6 g l−1 for M. anisopliae RS-4-1 and Trichoderma viride TV-1, and 8 g l−1 for Lecanicillium lecanii CA-1-G. The optimal conditions for P. lilacinus sporulation were 8 g l−1 carbon with a C:N ratio of 10:1 for M-14 and 12 g l−1 carbon with a C:N ratio of 20:1 for IPC-P, respectively. The results indicated that the influence of carbon concentration and C:N ratio on fungal growth and sporulation is strain dependent; therefore, consideration for the complexity of nutrient requirements is essential for improving yields of fungal biocontrol agents.