Download Suggested Answers for Insight Questions, Foundations in

Suggested Answers for Insight Questions, Foundations in Microbiology, 7th Edition, listed
by chapter, number, and page location.
A note to the users of these answers: These answers discuss some of the possible ways to
approach the questions. They are not meant to be exhaustive in depth, but can offer information,
suggestions, and points of view that will be helpful in understanding some of the concepts
covered in the Insight and the chapter. Furthermore, they are not the final word--you may have
thought of some other explanations that are just as valid. It is hoped they will serve to stimulate
class discussion and inspire further research.
26.1, pg. 794 – Greenhouse Gases, Fossil Fuels, Cows, Termites, and Global Warming
Microbes can adapt to a particular habitat, even one that is more extreme, but not all microbes
can adapt as rapidly as would be necessary. An ocean temperature that warms even a few
degrees over a relatively short time can adversely affect the growth of phytoplankton. The algae
may die off in great numbers before they can adjust their metabolism to operate at higher
temperatures. Scientists have already begun to observe such a scenario in the northern Pacific
Ocean. Reduction in the phytoplankton affects all other organisms that rely on them as the
primary producers, even other microbes, such as zooplankton and bacteria, and this extends on
up the food chain. The important point is, that all life is interconnected, and if climate changes the
abiotic environment and permanently alters a well established ecological balance, it can be lost
forever. Another factor is that microbes often exist in close associations and biofilms with other
organisms in soil and around plant roots. If the more sensitive members of these communities
are wiped out by global climate change, this can be expected to have far-reaching affects.
The
warming of the earth affects the hydrologic cycle, the carbon cycle, and probably other
biogeochemical cycles. One of the problems we face is that the ecological systems are
extremely complex and we do not yet know or understand all of the factors or potential effects of
these changes.
26.2, pg. 798 – Bioremediation: The Pollution Solution?
One possible technology would involve production of specialized enzymes tailor-made to degrade
certain pollutants into harmless residues. These enzymes could be manufactured in large
quantities by genetic engineering techniques and designed to remain functional in the
environment for an extended period. Another potential solution, and one that has been adopted
in parts of Europe is to convert solid waste into useful products. The waste items are sorted and
compressed or incinerated into blocks that can be used as building materials. Even microbes
cannot degrade a lot of the materials being dumped into land- fills. So they will sit there for eons,
and who knows what the ultimate effect will be? Recycling is in fact an excellent way to manage
waste. Many large municipalities recycle nearly every type of household waste, and large
industries have built up around the capture and reuse of such materials. One recent process in
development can convert practically any household waste into biodiesel that could power
automobiles.
26.3, pg. 804 – The Waning Days of a Classic Test
The coliform genera that are similar to E. coli but not as indicative of fecal contamination are
primarily Enterobacter, Klebsiella, and Citrobacter. (See page 608) These bacteria are normal
residents of the large intestine, but can also be found in soil, water, and on plants. Their
presence in food is often due to environmental contamination rather than contact with feces.
These bacteria are generally not highly virulent and are primarily opportunistic in their mode of
attack. In addition, they tend to cause infections of organs or organ systems other than the
intestine. Enterobacter is often associated with surgical infections and septicemia; Citrobacter
occasionally infects the urinary tract and blood in debilitated patients; Klebsiella pneumoniae is a
frequent cause of hospital-acquired pneumonia and wound infections. It all comes down to
susceptibility and portal of entry. Most people who ingested the iced tea were not
immunocompromised and others did not offer the correct portal of entry to allow invasion. The
normal host defenses would have kept the microbes in check. Probably every day we ingest
bacteria in our food that are listed as potential pathogens, but we do not get infected by them. If
the bacteria in the iced tea had been one of the variants of E. coli that infect the intestine, the
outcome would have turned out quite differently!