Mixed Cultures
Why should engineers know something about the ways in which different microorganisms
interact ?
Food engineers
Traditional fermented foods use microbial cultures that take over the system
and outcompete others. Pickles, cheeses, sauerkraut, and the like may use
an inoculum with selected microorganisms, but a useful culture may result
from natural selection from the organisms that are always present. Understanding
how this works and why it sometimes does not work and leads to contamination
can be important.
Some foods get two or more different microorganisms in the inoculum
because this can lead to a desired texture and flavor. The details and
theory of what is happening are poorly understood.
Biochemical engineers
There has been a great investment of time and money to get the best strains
that produce the most product economically. These strains are not intended
to compete well against foreign organisms or against their own kinds that
are slightly different because of mutation or natural variations. Preventing
challenges from other strains or minimizing the damage can save a great
deal of money.
Environmental engineers
Biological waste treatment steps are often plagued by upsets due to changes
in the microbial flora.
Lakes, impoundments, and streams have major changes in taste, odor, clarity,
and suitability for conversion to drinking water because of changes in
the organisms present.
Organisms in effluents can affect corrosion, coat or clog conduits, and
determine the plant or animal life downstream.
NEXT
while on sabbatical leave at ESB in Porto, Sept.
96