Freezing kills all bacteria, b/c the ice crystals disrupt the cell
wall.  Is the same true for viruses?  If not, why not?

Thanks

In short, your first statement is false.  It is not true that freezing
kills all bacteria, especially those that are adapted to living in
cold environments (such as the polar ice caps).  It is more
appropriate to say that some of the bacteria will be killed, while
others go into a dormant state awaiting thaw. Also, there is no reason
to believe that freezing kills viruses either.

Boiling (or autoclaving) is a much more effective method for
disinfecting a specimen.  These methods permanently denature the
proteins and ultimately cause "death" in microbes.

Oh... I also wanted to give you this website

http://www.fsis.usda.gov/OA/pubs/freezing.htm

I hope this info helps :)

--Rcubed

Thank you very much. Yes, this answers my question.

It is not true that bacteria are killed by freezing since there are
some which are resistant to harsh conditions. membrane disruption due
to freezing is possible, but in case of viruses, the genomic DNA/RNA
without the viral protein (envelope)is  sufficient for it to
resurvive. it has the ability to direct the host cells to code fresh
proteins necessary for the viral protein coat, whereas bacteria cannot
do it. hence, many viruses cannot be killed by freezing since nucleic
acids are stable at very low temperatures. however, the nucleic acids
can be destoyed by heat i.e either autoclaving or direct heating. hope
this helps.

Thank you, biochemist.  That definitely helps.

Charles