Biomedical Engineering Reference
In-Depth Information
fat droplet
fat droplet
fat droplet
fat droplet
f
(
fat droplet
Figure2.7
Biosurfactants
tails which allow them to act as surfactants and in this specific context, bio
surfactants. The most common surfactants are glycolipids (Figure 2.7), which do
not have a glycerol backbone, but have sugar molecules forming a polar head and
fatty acids forming non-polar tails, in an overall structure similar to that shown for
phospholipids in Figure 2.2. Derived lipids include fat soluble vitamins, natural
rubber, cholesterol and steroid hormones. It is interesting to note here that bacteria
do not synthesise steroids, and yet some, for example
Comamonas testosteroni
,
are able to degrade specific members of the group; testosterone in the case given
(Horinouchi
et al
., 2001). However, oestrogen and its synthetic analogues used in
the contraceptive pill are virtually recalcitrant to decomposition by bacteria. This
can prove to be a problem in waterways especially in Canada where the level of
such endocrine disrupters has been so high in some lakes that the feminisation
of fish can be a concern (McMaster, 2001). This subject, and similar findings for
the UK, are explored further in Chapter 3.
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