A Novel Liquid Medium for the Efficient Growth of the Salmonid Pathogen Piscirickettsia salmonis and Optimization of Culture Conditions

Abstract

Piscirickettsia salmonis is the bacterium that causes Piscirickettsiosis, a systemic disease of salmonid fish responsible for significant economic losses within the aquaculture industry worldwide. The growth of the bacterium for vaccine formulation has been traditionally accomplished by infecting eukaryotic cell lines, a process that involves high production costs and is time-consuming. Recent research has demonstrated that it is possible to culture pure P. salmonis in a blood containing (cell-free) medium.In the present work we demonstrate the growth of P. salmonis in a liquid medium free from blood and serum components, thus establishing a novel and simplified bacteriological medium. Additionally, the new media reported provides improved growth conditions for P. salmonis, where biomass concentrations of approximately 800 mg cell dry weight L−1 were obtained, about eight times higher than those reported for the blood containing medium. A 2- level full factorial design was employed to evaluate the significance of the main medium components on cell growth and an optimal temperature range of 23–27°C was determined for the microorganism to grow in the novel liquid media.Therefore, these results represent a breakthrough regarding P. salmonis research in order to optimize pure P. salmonis growth in liquid blood and serum free medium.

Transcriptome Analysis of the Intracellular Facultative Pathogen Piscirickettsia salmonis: Expression of Putative Groups of Genes Associated with Virulence and Iron Metabolism

“…Bacterial cells were harvested when the infected monolayers reached 95–100% cytopathic effects (CE). A supplemented liquid medium modified from Henriquez et al [5] was used that contained 8 g L -1 yeast extract, 4 g L -1 peptone from meat, 1.32 g L -1 (NH 4 ) 2 SO 4 , 0.1 g L -1 MgSO 4 , 6.3 g L -1 K 2 HPO 4 , 9 g L -1 NaCl, 0.08 g L -1 CaCl 2 , 3% glucose and 0.03 g L -1 FeSO 4 .…”

“…In vitro can be cultured in cell lines as CHSE-214 (Chinook salmon embryo), macrophage/monocyte (RTS-11) or Sf21 (Spodoptera frugiperda; ECACC 89070101) cell culture, where P . salmonis has high titers) [4]; and also in cell-free culture media, as CHAB agar, AUSTRAL-SRS broth or MC medium [5–7]. …”

Immunization Strategies against Piscirickettsia salmonis Infections: Review of Vaccination Approaches and Modalities and Their Associated Immune Response Profiles

“…Piscirickettsia salmonis , the causative agent of SRS is a Gram-negative, non-motile, non-encapsulated, 0.5–1.5 μm, intracellular bacterium (1, 13) that also grows in vitro in cell-free media (14–16). The bacterium is classified into a new family Piscirickettsiaceae in the phylum Proteobacteria, class Gammaproteobacteria , and order Thiotrichales (1).…”

Comprehensive antibiotic susceptibility profiling of Chilean Piscirickettsia salmonis field isolates

“…, ; Henriquez et al . ). But a method for the quantitative study of antibiotic resistance of P. salmonis was just recently reported (Yanez et al .…”