Abstract: To research the bioinformatics on the nifH gene of endophytic nitrogen-fixing bacteria Klebsiella variicola GN02 isolated from Pennisetum giganteum, the nifH gene of GN02 strain was cloned and its integrity was verified, and bioinformatics prediction and analysis of nifH gene were carried out by a variety of online biological software. The results showed that the nifH gene of GN02 strain had a complete ORF, length of 882 bp and encoded 293 amino acid, and the gene accession numbers registered in NCBI GenBank was MK131264. Bioinformatics analysis showed that the nifH gene of GN02 strain was highly conserved and had more than 95% homology with the nucleotide sequence and amino acid sequence of nifH gene from other species. The total relative molecular weight of nifH protein was 31 970.73 and the theoretical isoelectric point pI was 4.72. The transmembrane model inclined to the inward to outward transmembrane of N-end, and the whole polypeptide chain was hydrophilic. nifH protein had two glycosylation sites but no signal peptide secretion, which may had a helical crimp structure. The prediction of secondary structure showed that α-helix and irregular curl were the main structural elements in the polypeptide chain of nifH protein, and the extended chain was scattered in the whole protein. Three-dimensional homologous modeling of nifH protein can be carried out in the database.

Key words: Pennisetum giganteum, endophytic nitrogen-fixing bacteria, Klebsiella variicola, nifH gene, cloning, bioinformatics