The Roseobacter CHAB-I-5 cluster makes up to 20% of Roseobacters and 6% of bacterioplankton cells in surface oceans. Their genomes provide evidence of genome streamlining and the metabolic potential for aerobic anoxygenic photosynthesis (AAnP). Physiological tests of these processes has not previously been possible due to the inability to reliably propagate live cultures. We have isolated a new CHAB-I-5 representative, US3C007, from surface waters at the San Pedro Ocean Time Series (SPOT) through dilution-to-extinction cultivation techniques in artificial seawater media. Preliminary 16S rRNA gene identification using NCBI BLAST resulted in a 100% match to the previously published isolate, SB2, that was lost. We sequenced US3C007’s genome using a combination of long and short reads and assembled using Flye, which resulted in a complete circular genome at 3,622,411 bp. US3C007 and SB2 share 98.68% average nucleotide identity to each other, making US3C007 an ideal candidate to understand CHAB-I-5 physiology. Scanning electron microscopy shows pleiomorphy in the axenic culture with most cells exhibiting coccobacillus shape in doublets or lines of quadruplets. Salinity tolerance experiments showed growth at salinities between 28-40.5, with an optimum salinity of 33.7 at an average of 0.72 doublings/day. Temperature tolerance experiments showed growth between 16˚C-26˚C. Preliminary genomic analysis indicates the presence of genes for AAnP in our isolate, and ongoing work is focused on verifying AAnP, single nitrogen source utilization, and carbon requirements for US3C007.

Primary Presenter: V. Celeste Lanclos, University of Southern California (lanclos@usc.edu)

Authors:

V. Celeste Lanclos, University of Southern California  (lanclos@usc.edu)

Cole Hider, University of Southern California  (chider@usc.edu)

Xiaoyuan Feng, Chinese University of Hong Kong  (asdfeng188@gmail.com)

Jordan Coelho, University of Southern California  (jtcoelho@usc.edu)

Shelby Barnes, University of Southern California  (shelbyba@usc.edu)

Yanlin Zhao, Fujian Agriculture and Forestry University  (yanlinzhao@fafu.edu.cn)

Haiwei Luo, Chinese University of Hong Kong  (hluo2006@gmail.com)

J. Cameron Thrash, University of Southern California  (thrash@usc.edu)