Lysobacter penaei sp. nov., isolated from intestinal content of a Pacific white shrimp (Penaeus vannamei).

The polyphasic taxonomic approach was used to characterize a novel bacteria strain, designated SG-8T, which was isolated from intestinal content of a Pacific white shrimp (Penaeus vannamei). Cells were Gram-stain-negative, aerobic, non-gliding rods. Growth occurred at 10-45 °C (optimum, 20-30 °C), pH 5.0-10.0 (optimum, 6.0-7.0) and in 0-6.0 % (w/v) NaCl (optimum, 0-4.0 %). The 16S rRNA gene sequence of strain SG-8T showed the highest sequence similarity to Lysobacter maris KMU-14T (98.6 %). On phylogenetic trees, strain SG-8T formed a stable cluster with Lysobacter maris KMU-14T, Lysobacter alkalisoli SJ-36T, Lysobacter spongiae 119BY6-57T and Lysobacter aestuarii S2-CT. The average nucleotide identity and digital DNA-DNA hybridization values between strain SG-8T and the four reference type strains listed above were 83.3, 82.3, 83.5, 83.3% and 22.8, 22.7, 22.7, 22.9 %, respectively. The major fatty acids (>5 %) were iso-C15 : 0, summed feature 9 (iso-C17 : 1 ω9c and/or 10-methyl C16 : 0), iso-C16 : 0, summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c), iso-C17 : 0, iso-C11 : 0 3OH and iso-C11 : 0. Ubiquinone-8 (Q-8) was the only respiratory quinone. The major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. The DNA G+C content was 68.8 mol%. Based on the results of genomic, phylogenetic, phenotypic and chemotaxonomic analyses, strain SG-8T represents a novel species of the genus Lysobacter, for which the name Lysobacter penaei sp. nov. is proposed. The type strain is SG-8T (=GDMCC 1.1817T=KACC 21942T).

Phylogenomics insights into order and families of Lysobacterales.

Order Lysobacterales (earlier known Xanthomonadales ) is a taxonomically complex group of a large number of gamma-proteobacteria classified in two different families, namely Lysobacteraceae and Rhodanobacteraceae . Current taxonomy is largely based on classical approaches and is devoid of whole-genome information-based analysis. In the present study, we have taken all classified and poorly described species belonging to the order Lysobacterales to perform a phylogenetic analysis based on the 16 S rRNA sequence. Moreover, to obtain robust phylogeny, we have generated whole-genome sequencing data of six type species namely Metallibacterium scheffleri , Panacagrimonas perspica , Thermomonas haemolytica , Fulvimonas soli , Pseudofulvimonas gallinarii and Rhodanobacter lindaniclasticus of the families Lysobacteraceae and Rhodanobacteraceae . Interestingly, whole-genome-based phylogenetic analysis revealed unusual positioning of the type species Pseudofulvimonas , Panacagrimonas , Metallibacterium and Aquimonas at family level. Whole-genome-based phylogeny involving 92 type strains resolved the taxonomic positioning by reshuffling the genus across families Lysobacteraceae and Rhodanobacteraceae . The present study reveals the need and scope for genome-based phylogenetic and comparative studies in order to address relationships of genera and species of order Lysobacterales .