Abstract

Two Gram- stain-negative, motile, facultatively anaerobic, rod-shaped strains, FJAT-53720T and FJAT-53726, were isolated from rhizosphere sediment of plant Cyperus malaccensis. Phylogenetic analysis based on their 16S rRNA gene sequences revealed that strains FJAT-53720T and FJAT-53726 were affiliated to the genus Shewanella (forming an independent cluster) with the highest sequence similarity to the type strain of Shewanella algae. Optimum growth of both strains was observed at 30 degrees C and pH 7. The respiratory quinones were Q-7, Q-8 and MK-7. The polar lipid profile included phosphatidylmethyl ethanolamine, phosphatidylethanolamine, diphosphatidylglycerol, one unidentified aminophospholipid and four unknown phospholipids. The major fatty acids of strains FJAT-53720(T) and FJAT-53726 were iso-C-15:0, C-17:1 omega(8)c and summed feature 3. The genomic DNA G+C content of strain FJAT-53720(T) was 55.6 mol%. The average nucleotide identity (ANI) and digital DNA- DNA hybridization (dDDH) values between FJAT-53720T and FJAT-53726 were 97.4 and 77.9 %, confirming that they were similar species and hence FJAT-53720T was selected for further analysis. The ANI and dDDH values between FJAT-53720T and other members of the genus Shewanella were below the cut -off level (95-96 %; 70 %) for species delineation. Based on the above results, FJAT-53720T represents a novel species of the genus Shewanella, for which the name Shewanella cyperi sp. nov. is proposed. The type strain is FJAT-53720T (=KCTC 82444(T)=GDMCC 1.2207(T)).