Milk-borne viruses and toasty bacteria

Today I learned about two interesting items:

• Human mammary tumor virus (HMTV) exists. There's a retrovirus in mice with the straightforward name of Mouse mammary tumor virus (MMTV) and, as the name implies, it's linked with mammary tumors in mice. Mother mice carrying the virus pass it to their pups through milk. HMTV is the human-specific equivalent of MMTV. That's about all I can say without venturing into the realm of contentious debate: we can't really say whether either virus directly causes breast cancer in humans. Even so, it tends to show up frequently in women who've had breast cancer and it's not the only type of retrovirus found in milk.
• A paper from this past June (citation below) claims to have improved the heat tolerance of E. coli by expressing a heat shock protein from C. elegans in them. It's unusual to express C. elegans proteins in E. coli as they aren't even in the same domain of life (that being said, we regularly express viral proteins in our cells of choice in the lab and no one thinks twice about it). The authors claim that this heterologous expression allowed the experimental E. coli to grow at temps up to 50 degrees C and even briefly at 58 degrees. That's really hot - I've never been able to grow it above 42 degrees myself. I'm skeptical, not the least of which because there's some substantial speculation going on in this paper, but the results can't be that difficult to replicate, right?

Citation for that second item: Ezemaduka, A. N. et al. A small heat shock protein enables Escherichia coli to grow at a lethal temperature of 50°C conceivably by maintaining cell envelope integrity. J Bacteriol 196, 2004–2011 (2014).