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Northwest A&F University (2021)

Study on Genetic Diversity and Functional Characteristics of Bacillus in Two Arid and Barren Soils


Titre : Study on Genetic Diversity and Functional Characteristics of Bacillus in Two Arid and Barren Soils

Auteur : 白文卿

Grade : Master 2021

Université : Northwest A&F University

Résumé partiel
Bacillus is a common gram-positive bacteria in nature.It is widely used in agriculture and animal husbandry production due to the functions of biocontrol,plant growth-promotion,and insecticide.Therefore,it is of great significance to isolate Bacillus with adaptation to stress environment and wide application in agriculture.In this study,we isolated and screened Bacillus strains from the barren soil of desert and farmland in the arid area of northwestern China.The followings were carried out,1)To reveal its diversity and determine the phylogenetic status by 16S r RNA gene sequence analysis ;2)To rescreen strains that can antagonize Phytophthora sojae induced root rot and Rhizoctonia solani induced wheat sheath blight through plate antagonism experiments ;3)To obtain strains with excellent growth-promoting functions through the growth-promoting related characteristic test ;4)finally,to verifies its growth-promoting and stress-resistant effects on crops with inoculating pathogen and bacillus by the plant experiment.The main conclusions obtained are as follows :(1)A total of 202 strains of Bacillus were isolated in this experiment.By 16S r RNA gene sequences analysis,it was found that these strains could be classified into 16 groups,of which including 49 strains related to Bacillus tequilensis(24.2%)and 45 strains related to B.siamensis(21.9%).B.licheniformis(34,16.8%),B.subtilis(18,8.9%),and B.halotolerans(16,7.9%).177 strains of Bacillus were isolated from the poor soil of farmland,which mainly were classified into ten close related Bacillus species,including B.licheniformis(34 strains account for 19.2%),B.siamensis(44,24.8%),of B.tequilensis(49,27.7%) ;A total of 25 Bacillus strains were isolated from the desert,which mainly were classified into nine close related Bacillus species,including B.halotolerans(10 strains account for 40%),B.pumilus(4,16%),B.tropicus(2,8%),and B.wiedmannii(2,8%)(8%),B.atrophaeus(2,8%),etc.(2)The Bacillus strains were tested against Phytophthora sojae and Rhizoctonia solani,and it was found that 28 Bacillus strains had high antagonistic ability,including 13B.siamensis strains,five B.halotolerans strains,and five B.halotolerans strains.Amomg them,three B.tequilensis strains,two B.subtilis,three B.safensis subsp.safensis,one B.velezensis and B.pumilus had a higher bacteriostatic rate with more than 50%.Tests on the characteristics of phosphate-solubilizing bacteria,degrading organic phosphorus,dissolving potassium,cellulose,and producing iron carriers were carried out,ten strains with 4 kinds of growth-promoting properties were screened,these strains included B.siamensis(six strains),B.subtilis(two strains),B.velezensis(one strain),B.safensis subsp.(one strain)and B.pumilus(one strain)

Mots clés : poor soil ;bacillus;diversity ;biological control ;plant growth-promoting ;

Présentation (CNKI)

Page publiée le 20 mars 2022