| Actinomycetes is an important producer of active secondary metabolism and an important source of natural products.With the increase of drug resistance,to screem,isolate,identify,and study the active actinomycetes from various environments is particularly important,which made it possible to find alternatives that have potential for proprietary medicines.An actinomycetes strain Z331-A isolated from coastal saline soil was studied by observing its morphological characteristics,culture characteristics,physiological,biochemical characteristics and identifying its molecular biology characteristics.Thus the taxonomic status was determined.The bacteriostatic activity of fermentation broth and the activity of promoting plant growth were studied,and the following results were obtained by optimizing the culture conditions of liquid fermentation.1.Through the analysis of 16s rDNA sequence and phylogenetic analysis,it was found that strain Z331-A was closely related to Streptomyces rochei NBRC 12908,which was located in the same branch of phylogenetic tree and the similarity was 99%.Compared with the original Streptomyces rochei strain,the culture characters,morphological characteristics,physiological and biochemical characteristics of the strain Z331-A are very similar,so it is classified as Streptomyces rochei.The sequence has been registered on the NCBI website,and the login serial number is MF383408.1.2.The inhibitory activity of Z331-A fermentation broth against 7 plant pathogenic fungi was determined by the method of toxic medium.The results showed that the fermentation supernatant had inhibitory effect on the seven plant pathogens tested,and the inhibition rate was 20.00%to 69.10%.The antifungal ability of Colletotrichum lagenarium,Phylophthora nicotianae and Fusarium mangiferae were strong,their antifungal rate was 69.10%?63.89%and 62.50%respectively.The antibacterial activity of Z331-A fermentation broth against 7 kinds of bacteria was determined by disk diffusion method.The results showed that Z331-A had effect on Staphylococcus aureus ATCC 6538,Vibrio parahaemolyticus,Escherichia coli coilus ATCC 25922,Bacillus subtilis ATCC 6633,Bacillus proteus CMCC49027,MASA ATCC 43300,and MASA ATCC 35951,the inhibit diameter was 20.01mm,13.02mm,16.03mm,8.10mm,15.10mm,14.00mm,12.20mm respectively.3.The fermentation broth of Z331-A fermented in ISP-2 medium was selected from 6 kinds of culture medium to obtain the best bacteriostasis effect on bacteria.Based on ISP-2 medium,the fermentation conditions of strain Z331-A were optimized by response surface method.Results that the optimum fermentation conditions were obtained as follows:fermentation time was 7.20 days,inoculation amount was 5.70,rotation speed was 210 r/min,the volume of liquid was 30 mL 100mL-1,and culture temperature was 28 ?.The activity of the fermentation broth Z331-A against Bacillus subtilis was improved 26.56%compared with that before optimization.And the activity of fermentation broth to MRSA also increased by 25.00%.4.The stability of Z331-A fermentation broth under the optimum fermentation conditions was determined with MASA ATCC43300 as indicator.The effects of UV irradiation,pH and temperature on the diameter of bacteriostasis were studied.The results of bacteriostatic experiment showed that there was no significant difference in the bacteriostatic activity of fermentation broth within 1 h after UV treatment.After 6 h of UV treatment,the bacteriostasis circle still had 16.60 mm,which was 97.65%of control,indicating that Z331-A had good tolerance to ultraviolet irradiation.The fermentation broth was treated for 1 h at pH 5?8,and there was no significant difference in activity.When the fermentation broth was treated under the condition of strong acidity of PH2 and strong alkalinity of PH10,the diameter of the bacteriostasis circle was 16.80 mm and 16.10 mm,respectively,which was 98.82%and 94.70%of the control,respectively.The results show that the fermentation broth not only has no loss of activity under neutral,weak acid and weak basic conditions,but also has good resistance to strong acid and alkalinity,and it is stronger than that of alkali resistance.When the treatment temperature was from 50 ? to 70 ? there was no significant difference in the activity of fermentation broth.When the treatment temperature was 80??90??100?,the diameter of bacteriostasis circle was 16.50 mm?13.92 mm?8.26 mm respectively,and the activity was 97.60%?81.88%and 48.59%respectively.The activity is zero only when the temperature reaches 120 ?.The results showed that the active substances of the fermentation broth had better temperature tolerance.5.The effects of four different concentrations of Z331-A fermentation supernatant on tomato growth were determined.The results showed that 100 times diluent(106cfu/mL),500 times diluent(2×105 cfu/mL)and 1 000 times diluent(105cfu/mL)could significantly promote the germination of tomato seeds,the growth of radicle and radicle,and the increase of plant height,root length,fresh weight and dry weight of tomato seedlings.The effect of 100 times diluent treatment was the most obvious,and the conciseness index of seeds was the highest.Compared with CK treatment,tomato seedling plant height,root length,fresh weight and dry weight increased by 115.29%?113.33%?115.52%and 110.26%,respectively.The fermentation medium(108 cfu/mL)inhibited the germination of tomato seeds,the growth of young embryos and the increase of plant height,root length,fresh weight and dry weight of tomato seedlings,but promoted the content of leaf green a,leaf green b and total chlorophyll of tomato seedlings. |
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