Haloarchaea

In 2012, Aharon Oren wrote a review on the family Halobacteriaceae, where he pointed out with some surprise that the “type species of the type genus of the family and the order” had not yet been sequenced. This was despite the genomes of strains R1 and NRC-1 having been reported years previously. I am happy to say that today this deficit has been remedied, as described in our recent publication in Microbial Resource Announcements, and sequence submissions to Genbank, under accessions  CP038631 (chromosome), CP038632 (pHSAL1), and CP038633 (pHSAL2). Assembly of these replicons was not a straightforward task, as there were very large repeats, and considerable genomic variability. We are currently working on a more detailed analysis of this sequence.

Isolation of the type strain (91-R6) was originally described 85 years ago in a publication by Dr Allan Grant Lochhead (1934), while he was working at the Bacteriological Laboratory in the Experimental Farms System (part of the Canada Department of Agriculture). The strain was recovered from the red-discolouration of a salted cowhide (called ‘read heat’ in the trade), and the source of the organism was shown to be the salt used in tanning. Below is a picture of Allen Lochhead taken from the book he published in 1968 entitled “A history of the Bacteriology Division of the Canada Department of Agriculture 1923 – 1955”.

Allen had a fascinating and productive life. Born and educated in Canada, he left in 1912 to do his Ph.D. studies in Leipzig (Germany), and in 1914 was interned there for the rest of WW1. Returning to Canada in late 1918, he was appointed Lecturer in Bacteriology at MacDonald College, later shifting to Canadian Milk Products, then the Malt Products Company, and in 1923 landed the top position at the newly created Division of Bacteriology of the Dominion Dept. of Agriculture – a position he held until 1955. He became a leading expert on soil microbiology, with numerous publications and practical applications, and active in many professional societies. He was elected president of the Canadian Society of Microbiologists 1953-54. He died on Jan 5th, 1980.

The paper is now published and can be found at: https://www.mdpi.com/2073-4425/10/3/194

This was the second of two papers we published in the Genes special issue,  Genetics of Halophilic Microorganisms. The story behind this paper is interesting. In 2007, there was an unexpected lysis event of a large culture of Halobacterium salinarum S9 that was being grown at the MPI for the production of bacteriorhodopsin. This caused a real mess. The culprit was a myovirus (pictured upper right) that not only looks similar to phiH1 and phiCh1 but is specifically related to them. As depicted in the above light-hearted graphic, not only was the culture lost but the room had to be thoroughly cleaned out. The most likely source of contamination was the raw salt used for medium formulation. In honour of the mess and disorder caused by this virus, we coined the name ChaoS9 for it (Caudovirus of haloarchaeal origin; S9).

Read more “ChaoS9 – a novel halovirus”

The genome sequence of the classic model halovirus phiH1 has just been published as part of a special thematic issue of Genes. Get the paper here.  There is more to this story (click ‘read more’).

Read more “Halovirus phiH1”