Isolation, Selection And Identification Of Endogenous Microbe From Capsicum And Evaluation It’s Effects In Anti-Disease

Postharvest disease of fruits and vegetables is one of the main factors which affect the preservation and storage, the use of preservatives or antistaling agents is still the main measures to reduce the disease at the recent, but the residual pollution is caused when the dosage is no well, continuous use is easy to induce drug resistance of pathogenic bacteria, environmental pollution is caused, damage people’s health and so on. There are large amounts of endophytes can be used as bio-control bacteria will be a new repository in healthy plants, and they would have a good application prospect in terms of researching for new controlling postharvest diseases of fruits and vegetables.This paper is aim to select a endogenous strain of antagonism X which isolated from healthy plants, the strain has obvious antibacterial effect to Phytophthora capsici, Pepper green mildew, and C.gloeosporioides. And mainly introduce the strain isolation, screening and identification, the culture medium and fermentation conditions is optimized is to improve the ability of its bacteriostatic effect, application effect of postharvest fresh-keeping of pepper is evaluated and biological control is preliminary researched of postharvest diseases of pepper. The main conclusions are as follows:1. Phytophthora capsici, Pepper green mildew, and C.gloeosporioides as pathogens, antagonism effect of endogenous bacteria strains are selectivity separated from a health chili plant stem, leaf, fruit pulp with the method of dilute separation. A strain X of obvious antagonism effect is isolated with the method of screening, and concludes the inhibition rate between34.80%,48.0%.With the morphological observation, the bacteria colony is lesser, the pale white, not transparent, intermediate processes, semi-humid, edge neat; The bacteria is gram positive bacillus, individual small, rods, in pairs, sometimes into a chain. With the analysis of UltrafleXtreme MALDI-TOF-TOF sequences, find that the homology between gene sequence and the strain of Bacillus genus (Bacillus) is99%,therefore,the strain is determined B.amyloliquefaciens, and named X. 2. The optimum temperature of the endogenous bacteria X is28℃with the method of single factor experiment; When pH7.0and the inoculation quantity increases from0.6%to1.0%,the inhibition rate also increases from37.67%to65.78%; Different carbon source is added in the culture medium, and the glucose is added in the nutrient solution, the best inhibition of pathogenic bacteria is70.11%; Followed by soluble starch, sucrose, maltose and lactose,65.34%,60.32%,44.12%and35.68%respectively, the minimal inhibitory effect of lactose among them. When different nitrogen source, as yeast extract, beef extract peptone, NH4ClO and KNO3is added, the inhibitory action of antagonistic bacteria reduce in proper sequence, the rate of inhibition of pathogenic bacteria is72.64%when yeast extract is added. Followed by beef cream, peptone,NH4ClO and KNO3,the inhibition rate of pathogenic bacteria is60.13%,58.97%,42.55%,58.97%respectively, The minimum inhibitory effect is KNO3among them; with different metal ions are added in the nutrient solution, the best inhibition rate is65.11%when NaCl is added, Followed by CaCl2, KH2PO4, FeSO4and MnSO4, inhibition rate of pathogenic bacteria is57.28%、53.23%、45.46%、40.25%respectively, of which the synergy of MnSO4is minimal. The multifactor experiment was carried out based on single factor test results, through the response surface experiment of four factors, five levels, the most suitable to the growth of strains X and best bacteriostatic effect is obtained, the inoculum quantity0.80%, yeast extract0.5%,glucose2.5%,NaCl0.13%, the maximum inhibition rate of pathogenic bacteria is73.02%on the condition of the strains of pathogenic bacteria X, higher than the inhibition rate48.0%without optimization of cultivation conditions. The best medium of ntagonism of endophytes X is the inoculum quantity0.80%, yeast extract0.5%,glucose2.5%, NaCl0.13%,pH7.0. the temperature of Culture conditions is28℃, and rotational speed180r/min.3. Antagonistic endophytic bacteria X has a certain impact on postharvest fresh-keeping and bacteriostasis effect of fresh chili and the storage time and temperature factors. Either in room temperature25℃or in cold storage conditions5℃, the fermentation filtrate of antagonistic bacteria all has bacteriostatic effect to pathogenic bacteria. This paper shows that the main disease of the chili are soaked during the storage at room temperature is Phytophthora capsici, Pepper green mildew, but the disease is Phytophthora capsici in cold storage conditions5℃. Under the condition of room temperature25℃,the concentrations of1%,2%and3%antagonism of endophytic fungus fermentation filtrate cause the Phytophthora capsici of soaked chili,the disease incidence is45%,38%and56%respectively,but under the condition of the control group of sterile water, the disease incidence is79%,and the best concentration is3%;the disease incidence of Pepper green mildew is21%,18%and14%on the decline, and the control group was47%.Under the condition of room temperature5℃,the concentrations of1%,2%and3%antagonism of endophytic fungus fermentation filtrate cause the Phytophthora capsici of soaked chili, the disease incidence is10%,8%and7%respectively, but under the condition of the control group of sterile water, the disease incidence is27%,and the best concentration is1%;the disease incidence of Pepper green mildew is0%respectively, it shows that Pepper green mildew is controlled in the condition of room temperature5℃.After the artificial chili wound, the fermentation filtrate of antagonistic bacteria has bacteriostatic effect to pathogenic bacteria. It shows when the concentration was3%, it has the smallest diameter of the antibacterial circle,36mm. When its concentration is1%, the diameter of the antibacterial circle is45mm; when its concentration is2%, the diameter of the antibacterial circle is57mm; but the control group of sterile water, the diameter of the antibacterial circle is68m. The weightlessness rate of those chili with the extension of storage time are on the rise, but rising trend; In the test;the content of soluble solids in chili falls along with the time, from4.06%to1.31%; and the content of the organic acid is a downward trend, from3.15mmol/100g to0.96mmol/100g;Vc content in the extension of storage time are declining, but the downward trend is different.