| The entomopathogenic fungus, Paecilomyces fumosoroseus (Wize) Brown & Smith, is one of the most promising fungal species that is studied for control of whiteflies and other sucking insect pests and has been developed into several commercial formulations in North America in the past few years. However, little attention has been given to the potential of this fungal species against sucking insects such as aphids and whiteflies in China. As a part of effort to utilize P. fumosoroseus for control of sucking insects, this thesis is to investigate techniques involved in mass production, through diphasic fermentation, and drying of aerial conidia as effective inocula in formulation, and physiological features of the conidia in storage.A whitefly-derived isolate of P. fumosoroseus, Pfrll6, was used throughout the study. From five liquid media tested for submerged culture of the fungus at 25℃, a low-cost medium was selected for use in mycelial production. The medium included (w/v) 2% sucrose, 20% potato soup, and 0.1% peptone supplemented with 0.01% NaNO3,0.01% KC1, 0.025% MgSO4, 0.005% MnSO4, 0.005% FeSO4 and 0.05% KH2PO4. With this medium, a 48-h culture resulted in a mycelial biomass of >20 mg/mL, a yield very close to that produced using Sabouraud dextrose broth. Optional conditions for initiating the culture included a mycelial biomass of 1.5-2.0 mg/mL as a level of initial inoculum in the liquid medium, and a pH range from 5 to 7. The resulting liquid culture was then transferred to a mixture of rice chaff and wheat bran (7:3) for production of aerial conidia at different regimes of temperature (20, 24, 28 and 32℃) and relative humidity (51, 74, 85, 90%, 95, and 100%) through solid fermentation. The combination of 24℃ and 90% RH was most favorable to conidiation on the solid substrates. When the solid fermentation was maintained at this regime for the first 7 days and then continued at 24℃ and lower humidity until conidiation terminated, the yield of conidia powder dropped at 51 and 74% RH but not at 85% RH. When steamed rice was used as solid substrates for conidiation, a 30-mg yield of conidia per gram of rice was achieved with each gram containing 1.454 x 10" conidia and a water content of 12% before drying.In an attempt to explore a satisfactory method for drying the conidia of P. fumosoroseus Pfrll6 produced in diphasic fermentation, several drying methods and procedures were compared. These included high-vacuum freeze drying (HVDF), high-vacuum (15.86 Pa) drying at ambient temperature (HVDAT), heat drying at 35℃ (HD), and low-vacuum (0.1 MPa) low-heat (30℃) drying for 16-34 h (LVLHD). The 20- or 24-hLVLHD procedures were found being most suitable for drying of Pfrll6 conidia with the resulting powdery product containing 1.13-1.31x10" conidia per gram, 9.0% water content, and >87% viability. These indices all met requirements for industry standards. Thus, the LVLHD procedures can be applied to mass production of Pfrll6 conidia because equipment required for the procedures is inexpensive. Under the high vacuum conditions, both freeze and ambient temperature drying procedures resulted in powdery products of 1.27-1.36x10" conidia per gram with a satisfactory water content of 2.2-8.7% but a unsatisfactory viability of only 62%, which was significantly lower than that from the LVLHD procedures. Apparently, P. fumosoroseus Pfrll6 conidia were less tolerable to the high-vacuum drying procedures. The regular HD procedure yielded an acceptable product of 1.20x10" conidia per gram with a water content of 9.6% and a viability of 82.8%. However, this viability was significantly lower than those from the <24-h LVLHD procedures (P<0.05).While being preserved at 4 and 25, the powdery products of P. fumosoroseus Pfrll6 conidia with different water contents were examined for variation in viability and contents of intracellularly reserved saccharides and proteins. The results showed that the viability for conidia powder with higher water content dramatically declined at 25℃ during the storage whereas lower...
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