Studies On Fermentation Of Antagonistic Microbia (34-9) Against Penicillium Digitatum Sace And Penicillium Italicum Wehmer Of Citrus And Applying Of Biocontrol Agents

Postharvest diseases of citrus cause major losses, these diseases are primarily controlled by synthetic fugicides. A new, high efficacy and innocuity microbial biocontrol agent are needed to be producted instead of fungicide because people have concerned about environmental contamination and human health risks associated with fungicide residues and the widespread use of these fungicides has led to the proliferation of resistant strains of the pathogens.The aim of this research is to screen the fermentation media to cultivate the strain of 34-9, investigate the fermentation technology condition and study the effect on the strain of 34-9(Kloeckera apiculata) for biological control of postharvest diseases of citrus in extending application storage. Main conclusions were drawn as follows.1. The prime fermentation media were screened: on shaking flask level, the optimum carbon and nitrogen were screened by single-factor experiment in fermentation media. Then the optimum level of different metal ion media and different vitamin media were screened by orthogonal experiment. The optimum level of carbon, nitrogen, KH₂PO₄, and the yeast extract were also screened by orthogonal experiment the fermentation media was obtained to fit for the strain of 34-9: glucose 30g/L, (NH₄)₂SO₄ 2g/L, KH₂PO₄ 5g/L, MgSO₄·7H₂O 2.4 g/L, ZnSO₄·7H₂O 2 g/L, CaCl₂·2H₂O 0.12 g/L, NaCl 0.24 g/L, FeSO₄·7H₂O 0.01 g/L, biotin 0.5mg/L, D.calcium pantothenate usp/ip 6 mg/L, Thiamine hydrochloride 6 mg/L, lactoflavin 3 mg/L, peptone 15g/L, yeast extract 10 g/L.2. The prime shaking flask cultivating conditions were obtained: the shaking flask volume, fermentation time, the pH before sterilized and quantity of inoculation were investigated by orthogonal experiment. Study on rotate speed of rotary shaker and culture temperature, we found that rotate speed of rotary shaker was higher the product quantity of the strain of 34-9 was higher, the suitable fermentation temperature of the strain of 34-9 was 30℃.3. The fermentation technology was optimized: on fermentator level, the fermentation technology of the strain of 34-9 was screened through batch fermentation, intermission fed-batch fermentation and constant fed-batch fermentation. Fermentation concentration of the strain of 34-9 attended 5×10⁹CFU/mL and the wet weigh of the strain of 34-9 attended one hundred gram in every litre fermentation liquid.4. The effect of the biological agents (34-9) was researched for biological control of...