David Coil edited Results and Discussion.md  over 9 years ago

Commit id: fa00053aa1158a8502078b9d6e4b80b3ab994c38

deletions | additions      

       

Cells were non-motile and not observed to form spores or possess flagella, though over 30 flagella or flagella-associated genes are present in the genome. In contrast, the genome for a non-motile close relative (_P. cryptus_) does not contain any flagellar genes so it is possible that strain Coronado(T) is motile under specific conditions. Unlike most members of the _Erythrobacteraceae family_, strain Coronado(T) is oxidase and catalase negative. This strain is also unable to hydrolze casein or starch.  Cells were oval or rod shaped and ranged in length from 1.2um to 2.2um with an average of 1.6um (Figure XX). 1).  Cell width ranged from .6um to 1um with an average of .8um. Growth was only observed under aerobic conditions, from 4C to 28C, with optimal growth around 25C. Low levels of growth were observed at pH 6.0  up to pH 8.0, maximum growth occured around neutral pH. Salt was required for growth, and the strain could not grow at 3% >1.5%  NaCl, optimal growth was at 1% .5%  NaCl. Strain Coronado(T) could utilize the following as sole carbon sources: Glycyl-L-Glutamic Acid, L-Rhamnose, D-Mannose, D-Trehalose, a-D-Glucose, L-Fucose, D-Galactose, Citric acid, D-Glucuronic acid, D-Galactonic acid, L-Galactonic acid-\(\gamma\)-Lactone, Acetoacetic acid, Acetic acid, Pyruvic acid, and L-Malic acid.  

Phylogenetic analysis was performed using the full length (1482bp) 16S rDNA sequence from the genome assembly, not the shorter (1350bp) version from Sanger sequencing. The Coronado(T) 16S rDNA sequence showed only 95% identity to the phylogenetically closest relative, _Porphyrobacter sanquineus_, and identity was even lower throughout the rest of the tree. Given the low 16S rDNA identity to other members of the family, we did not perform DNA-DNA hybridization as this would have been uninformative \cite{STACKEBRANDT_1994}, \cite{Tindall_2010}  As discussed above, a large-scale taxonomic revision of the family is most likely in order given the lack of monophyly observed for most genera in the tree. tree (Figure 2).  For example, Coronado(T) is the basal member of a clade containing mostly _Porphyrobacter_ that has strong bootstrap support, but is polyphyletic with respect to both _Erythromicrobium_ and _Erythrobacter_. And, this clade falls within a well-supported polyphyletic clade of _Erythrobacter_. Based on this tree, we chose to compare Coronado(T) to the three genera in Table 1. Analysis of the draft genome of strain Coronado(T) was used to complement the physical characterizations typical of the family _Erythrobacteraceae_. For example, Coronado(T) does not contain any of the numerous genes involved in chlorophyll biosynthesis, rendering protein extraction/spectrophotometry unneccessary. Conversly, while no flagella were observed by TEM, this strain appears to possess the required genes making it likely that the flagella were lost in sample preparation or that their expression is condition-dependant.