Paucibacter toxinivorans gen. nov., sp. nov., a bacterium that degrades cyclic cyanobacterial hepatotoxins microcystins and nodularin

Abstract

Thirteen bacterial isolates from lake sediment, capable of degrading cyanobacterial hepatotoxins microcystins and nodularin, were characterized by phenotypic, genetic and genomic approaches. Cells of these isolates were Gram-negative, motile by means of a single polar flagellum, oxidase-positive, weakly catalase-positive and rod-shaped. According to phenotypic characteristics (carbon utilization, fatty acid and enzyme activity profiles), the G+C content of the genomic DNA (66?1-68?0 mol%) and 16S rRNA gene sequence analysis (98?9-100 % similarity) the strains formed a single microdiverse genospecies that was most closely related to Roseateles depolymerans (95?7-96?3 % 16S rRNA gene sequence similarity). The isolates assimilated only a few carbon sources. Of the 96 carbon sources tested, Tween 40 was the only one used by all strains. The strains were able to mineralize phosphorus from organic compounds, and they had strong leucine arylamidase and chymotrypsin activities. The cellular fatty acids identified from all strains were C 16 : 0 (9?8-19 %) and C 17 : 1 v7c (<1-5?8 %). The other predominant fatty acids comprised three groups: summed feature 3 (<1-2?2 %), which included C 14 : 0 3-OH and C 16 : 1 iso I, summed feature 4 (54-62 %), which included C 16 : 1 v7c and C 15 : 0 iso OH, and summed feature 7 (8?5-28 %), which included v7c, v9c and v12t forms of C 18 : 1 . A more detailed analysis of two strains indicated that C 16 : 1 v7c was the main fatty acid. The phylogenetic and phenotypic features separating our strains from recognized bacteria support the creation of a novel genus and species, for which the name Paucibacter toxinivorans gen. nov., sp. nov. is proposed. The type strain is 2C20 T (=DSM 16998

High diversity of cultivable heterotrophic bacteria in association with cyanobacterial water blooms

“…Earlier, known strains of bacteria that are able to degrade cyanobacterial toxins are mainly members of the family Sphingomonadaceae within the class Alphaproteobacteria and Paucibacter toxinivorans strains of the class Betaproteobacteria (Jones et al, 1994;Park et al, 2001;Saito et al, 2003;Ishii et al, 2004;Rapala et al, 2005;Amé et al, 2006). The presence of such bacteria in water may have an important role in the natural cleansing of the chemically stable hepatotoxins.…”

Quantification of Microcystin-degrading Bacteria in a Biofilm from a Practical Biological Treatment Facility by Real-time PCR

“…These results suggested that the strains without amplification products have an unknown mechanism for degrading microcystins. The existence of the mlrA gene was not confirmed in some microcystin-degrading bacteria, and therefore, further studies are required to elucidate the relationship between microcystin-degrading bacteria and the degradative mechanism of microcystins (Meriluoto et al, 2005;Rapala et al, 2005). In addition, the detection procedure using the new primers was compared to that using MF and MR primers that have been used to -197 -detect the mlrA gene in previous studies.…”

“…These strains are included in the genus Sphingopyxis by gene analysis. A Paucibacter strain was isolated from the sediment of a -195 -eutrophic lake in southern Finland (Rapala et al, 2005). These six strains were cultivated in 1/5 PY medium (1 g of peptone and 0.5 g of yeast extract per 1,000 mL).…”

Phylogenetic diversity of procaryotae and their contribution to excess sludge demineralization in a gravel contact oxidation reactor

“…It had the ability of indigenous microorganisms to degrade perchlorate more effectively at low concentrations of perchlorate [18], but also could photo-assimilated organic substrate into several kinds of organic acid. These results extend the current understanding of Perchlorate-reducing bacterium from diverse environments and provide added confidence that microbial perchlorate reduction is ubiquitous, even at highly contaminated sites, and can be harnessed effectively for bioremediation.…”