Anti-SYP monoclonal antibody, clone TQ26

A Gram-staining-negative, yellow-pigmented strain, designated SYP-B804(T), was isolated from the rhizosphere of Panax notoginseng. The strain was rod-shaped with a single polar flagellum. The optimum temperature and pH required for growth of the strain were 28-32 degrees C and pH 7-8, respectively. 16S rRNA gene sequence analysis indicated that strain SYP-B804(T) showed highest 16S rRNA gene sequence similarity with Luteimonas mephitis DSM 12574(T) (98.0 %). However, the DNA-DNA relatedness value between them (38.1 +/- 0.6 %) was less than the threshold value for the delineation of genomic species. Ubiquinone-8 (Q-8) was the predominant quinone. The major fatty acids were iso-C-15 : 0 and iso-C-17 : 1 omega 9c. The major polar lipids of the strain were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The G+C content of the genomic DNA was 71 %. On the basis of phenotypic, chemotaxonomic and molecular characteristics, strain SYP-B804T merits recognition as a representative of a novel species of the genus Luteimonas, for which the name Luteimonas notoginsengisoli sp. nov. is proposed, with SYP-B804(T) (=KCTC 42211(T)=JCM 30329(T)) as the type strain.

Vibrio (Aliivibrio) salmonicida is the etiological agent of cold water vibriosis, a disease in farmed Atlantic salmon (Salmo salar) that is kept under control due to an effective vaccine. A seawater temperature below 12 degrees C is normally required for disease development. Quorum sensing (QS) is a cell density-regulated communication system that bacteria use to coordinate activities involved in colonization and pathogenesis, and we have previously shown that inactivation of the QS master regulator LitR attenuates the V. salmonicida strain LFI1238 in a fish model. We show here that strain LFI1238 and a panel of naturally occurring V. salmonicida strains are poor biofilm producers. Inactivation of litR in the LFI1238 strain enhances medium- and temperature-dependent adhesion, rugose colony morphology, and biofilm formation. Chemical treatment and electron microscopy of the biofilm identified an extracellular matrix consisting mainly of a fibrous network, proteins, and polysaccharides. Further, by microarray analysis of planktonic and biofilm cells, we identified a number of genes regulated by LitR and, among these, were homologues of the Vibrio fischeri symbiosis polysaccharide (syp) genes. The syp genes were regulated by LitR in both planktonic and biofilm lifestyle analyses. Disruption of syp genes in the V. salmonicida Delta litR mutant alleviated adhesion, rugose colony morphology, and biofilm formation. Hence, LitR is a repressor of syp transcription that is necessary for expression of the phenotypes examined. The regulatory effect of LitR on colony morphology and biofilm formation is temperature sensitive and weak or absent at temperatures above the bacterium's upper threshold for pathogenicity.