Study On Prevention Mechanism Of Antagonistic Yeasts Against Broccoli Black Rot

Broccoli black rot infection and prevention mechanism was studied in this paper on the basis of separation, purification and identification of pathogenic bacteria, the regularity of infection.1.The main infection fungus is A.Alternaia brassicicola Ahernaria Nees, which belongs semi-brown, Hyphomycetes, Beam genus Monilia, Cabbage Alternaria fungi.2.Results from Alternaria alternata infection:During storage cabbage Alternaria fungi at low temperature (4℃ and 7℃) were able to grow, and in 0℃ it can not spore. The optimum pH conditions of pathogen was 8, cauliflower may contain some nutrients which appropriate Alternaria fungi growth.3.Pathogenic toxin infection was faster than pathogens through the study of broccoli physiological characteristics:the damage was greater, and phenylalanine ammonia-lyase, ×chitinase, pectinase, toxin treatment group of the enzyme activity peak appeared in advance than pathogen treatment group.4.1.0 × 105 CFU/mL yeast suspensions can inhibit the growth of pathogens well, and yeast concentration was greater, broccoli and black spot morbidity was lower, in the PDA medium, the antibacterial circle diameter was smaller, at the same time pathogen spore germination rate was smaller.1.3 × 105 CFU/mL concentration of yeast suspensions can be very good colonized in broccoli.Yeasts and pathogen interaction, pathogenic fungus mycelium expanded, high concentration (2.7 × 107 CFU/mL) under the action of yeast, pathogen hyphal cell wall was dissolved, spore constriction cracked and disintegrated.5.Yeast suspension inducing endogenous salicylic acid content increased in 4 h treated broccoli, but the control group did not change, the same concentration in the processing of broccoli 4 h yeast suspensions were vinyl release reached 5 μL/h/kgFW peak, while the control group had reached 6.85 μL/h/kgFW peak.6.Yeast DNA sequences similar to Mopu Pichia yeast (P.membranae faciens) at 99%. No pseudohyphal formated, cell were oval,5～7μm×3～5μm, cells for many budding, no throwing spores produced on glucose, sucrose, yeast fermentation, not other sugar fermentation.The maltose, lactose, raffinose, trehalose, fiber two sugar to assimilation.