Indication Of Bacterial Strain L5and Priliminary Analysis Of Related Factors To Bacterial Strain

Bacterial strain L5, isolated from the soil in district of Yangzhou, posesses of a broad spectrum of inhibiting the growth of plant pathogens such as botrytis cinerea, Magnaporthe grisea, rhizoctonia solani, fusarium graminearum, sclerotinia scleotiorum and usarium oxysporam. Although isolated from soil, it still have stronger antagonism to botrytis cinerea transmitted by air. The results showed that Bacterial strain L5, is a antagonism strain of the potential prevention ability, its suspension exhibit strong inhibition on the spores germination and the growth of botrytis cinerea, inhibition rate was98.37%and the prevention rate was72%, respectively through the spores germination inhibition experiment, biological detection of leaf and fruit in vitro.The results exhibited the bacterial strain L5could produce antibacterial substance such as pyrrolnitrin, lactoferrin and etc, and not produce hydrolase and protease through the analysis of related factors to bacterial strain. The strain L5was identified as Serratia odorifera based on sequence analysis of16S rDNA and16S-23S rDNA intergenic spacers (IGS physiological and biochemical characterization.The analysis of IGS sequence found two different types of IGS in bacterial strain L5.0ne included the tRNAGlu,and the other contained a cluster of tRNAIle and tRNAAla.Partial gene sites of pyrrolnitrin were cloned to bacterial strain L5to synthesize the gene cluster prnABCD by PCR and sitefinding PCR, measured gene sequence will compare with that in the Genbank. Th results showed that its gene cluster is higher similarity than the pyrrolnitrin synthesized by Serratia plymuthica G3, the similarity reached99%. the cloning slides composes of entire prnA, prnB, prnC and partly prnD gene sequence, gene sequence have been submitted to Genebank and registration number is JQ712667. The above forth opening reading frame all lie in the a transmition unit and transmition direction is from prnA to prnD.The full length of prnA is1598bp, the initiator codon is ATG, terminator codon is TAG; The full length of prnB is1086bp linking with the terminator of prnA and the initiator codon is GTG, terminator codon is TGA; The full length of prnC is1704bp that has a41bp distance to prnB, the initiator codon is ATG, terminator codon is TAQThe full length of prnD is1022bp linking with the terminator of prnC and the initiator codon is ATG. Up to now, Pyrrolnitrin gene cluster synthesized by Serratia odorifera have not been reported internationally.