Venatorbacter cucullus gen. nov sp. nov a novel bacterial predator

Phylogenetic Revisit to a Review on Predatory Bacteria

Predatory bacteria, along with the biology of their predatory behavior, have attracted interest in terms of their ecological significance and industrial applications, a trend that has been even more pronounced since the comprehensive review in 2016. This mini-review does not cover research trends, such as the role of outer membrane vesicles in myxobacterial predation, but provides an overview of the classification and newly described taxa of predatory bacteria since 2016, particularly with regard to phylogenetic aspects. Among them, it is noteworthy that in 2020 there was a major phylogenetic reorganization that the taxa hosting Bdellovibrio and Myxococcus, formerly classified as Deltaproteobacteria, were proposed as the new phyla Bdellovibrionota and Myxococcota, respectively. Predatory bacteria have been reported from other phyla, especially from the candidate divisions. Predatory bacteria that prey on cyanobacteria and predatory cyanobacteria that prey on Chlorella have also been found. These are also covered in this mini-review, and trans-phylum phylogenetic trees are presented.

Parathalassolituus penaei gen. nov., sp. nov., a novel member of the family Oceanospirillaceae isolated from a coastal shrimp pond in Guangxi, PR China

A Gram-stain-negative, strictly aerobic, rod-shaped and motile bacterium with bipolar flagella, designated G-43^T, was isolated from a surface seawater sample collected from an aquaculture in Guangxi, PR China. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain G-43^T was most closely related to the family Oceanospirillaceae and distantly to the most closely related genera Venatorbacter and Thalassolituus (95.52 % and 94.45-94.76 % 16S rRNA gene sequence similarity, respectively), while similarity values to other Oceanospirillaceae type strains were lower than 94.0 %. Strain G-43^T was found to grow at 4-30 °C (optimum, 25-28 °C), pH 6-9.0 (optimum, pH 7.0) and with 0-4.0 % NaCl (w/v; optimum at 2 % NaCl). Chemotaxonomic analysis of strain G-43^T indicated that the sole respiratory quinone was ubiquinone-8, the predominant cellular fatty acids were C_16 : 0, summed feature 3 (C_16 : 1 ω7c and/or C_16 : 1 ω6c) and summed feature 8 (C_18 : 1 ω7c and/or C_18 : 1 ω6c), and the major polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, aminolipid, diphosphatidylglycerol, phospholipids and an unidentified lipid. The G+C content of the genomic DNA was 55.4 mol%. The phylogenetic, genotypic, phenotypic and chemotaxonomic data demonstrate that strain G-43^T represents a novel species in a novel genus within the family Oceanospirillaceae, for which the name Parathalassolituus penaei gen. nov., sp. nov. is proposed. Strain G-43^T (=KCTC 72750^T= CCTCC AB 2022321^T) is the type and only strain of Parathalassolituus penaei.