Monday, 27 May 2019
Stephanie H. Chen joined the Edwards Lab at UNSW as a PhD student in May 2019. She is working on a collaborative project with the Royal Botanic Garden and Domain Trust and is co-supervised by Richard Edwards and Jason Bragg. Her research focuses on landscape genomics of Myrtaceae species (includes eucalypts, paperbarks, and tea-trees) and the genetic basis of resistance to myrtle rust, which is of pressing concern to Australia’s native biodiversity. She is also contributing to assembling and annotating the waratah (Telopea speciosissima) genome as part of the Genomics for Australian Plants Framework Initiative.
Stephanie holds a Bachelor of Science (Honours) (First Class Honours and the University Medal) from the University of Sydney, Australia, with a major in Plant Science.
Thursday, 23 May 2019
Complete genome sequences of pooled genomic DNA from 10 marine bacteria using PacBio long-read sequencing
Song W, Thomas T & Edwards RJ (2019) Complete genome sequences of pooled genomic DNA from 10 marine bacteria using PacBio long-read sequencing. Marine Genomics in press DOI: 10.1016/j.margen.2019.05.002
High-quality, completed genomes are important to understand the functions of marine bacteria. PacBio sequencing technology provides a powerful way to obtain high-quality completed genomes. However individual library production is currently still costly, limiting the utility of the PacBio system for high-throughput genomics. Here we investigate how to generate high-quality genomes from pooled marine bacterial genomes.
Pooled genomic DNA from 10 marine bacteria were subjected to a single library production and sequenced with eight SMRT cells on the PacBio RS II sequencing platform. In total, 7.35 Gbp of long-read data was generated, which is equivalent to an approximate 168× average coverage for the input genomes. Genome assembly showed that eight genomes with average nucleotide identities (ANI) lower than 91.4% can be assembled with high-quality and completion using standard assembly algorithms (e.g. HGAP or Canu). A reference-based reads phasing step was developed and incorporated to assemble the complete genomes of the remaining two marine bacteria that had an ANI > 97% and whose initial assemblies were highly fragmented.
Ten complete high-quality genomes of marine bacteria were generated. The findings and developments made here, including the reference-based read phasing approach for the assembly of highly similar genomes, can be used in the future to design strategies to sequence pooled genomes using long-read sequencing.
Friday, 10 May 2019
Preprint: Whole genome sequencing of a novel, dichloromethane-fermenting Peptococcaceae from an enrichment culture
Holland SI*, Edwards RJ*, Ertan H, Wong YK, Russell TL, Deshpande NP, Manefield M & Lee MJ (2019) Whole genome sequencing of a novel, dichloromethane-fermenting Peptococcaceae from an enrichment culture. PeerJ Preprints 7:e27718v1. DOI 10.7287/peerj.preprints.27718v1 [*Joint first authors]
Bacteria capable of dechlorinating the toxic environmental contaminant dichloromethane (DCM, CH2Cl2) are of great interest for potential bioremediation applications. A novel, strictly anaerobic, DCM-fermenting bacterium, “DCMF”, was enriched from organochlorine-contaminated groundwater near Botany Bay, Australia. The enrichment culture was maintained in minimal, mineral salt medium amended with dichloromethane as the sole energy source. PacBio whole genome SMRTTM sequencing of DCMF allowed de novo, gap-free assembly despite the presence of cohabiting organisms in the culture. Illumina sequencing reads were utilised to correct minor indels. The single, circularised 6.44 Mb chromosome was annotated with the IMG pipeline and contains 5,773 predicted protein-coding genes. Based on 16S rRNA gene and predicted proteome phylogeny, the organism appears to be a novel member of the Peptococcaceae family. The DCMF genome is large in comparison to known DCM-fermenting bacteria and includes 96 predicted methylamine methyltransferases, which may provide clues to the basis of its DCM metabolism. Full annotation has been provided in a custom genome browser and search tool, in addition to multiple sequence alignments and phylogenetic trees for every predicted protein, available at http://www.slimsuite.unsw.edu.au/research/dcmf/.
Thursday, 2 May 2019
Carla Aguilar Gomez was a visiting researcher in the lab from May to July 2019, working on SLiM prediction from cross-linking mass spectrometry data in yeast. Carla left the lab to move to Austria for a PhD in biotechnology.