from R&D Innovator Volume 1, Number 5
Neidleman is senior director of project acquisition and planning
at Biosource Genetics Corporation in Vacaville, California.
seeds of the jojoba shrub are another item in nature's apothecary,
used to produce an oil for many cosmetic formulations.
Because the oil is quite expensive to produce, I set out to
find an economical substitute.
thought a bacterium might prove an economical source of cosmetic
oil, because bacteria can produce lipids, and the process can be
controlled in a fermentor. There
was only one small problem--we found no reports of bacteria making
this particular type of oil.
is, however, a bacterium called Acinetobacter,
which makes a solid wax with many of the properties we wanted in
our substitute oil. Waxes
and oils are both lipids, and a great deal is known about how
bacteria produce and use lipids.
momentarily from the jojoba problem, a short biochemistry lesson
might be useful. Lipids
with varying properties, are an essential component of the
membranes that wrap around living cells.
At any given temperature, some lipids are more liquid and
others more waxy: Lard
is solid at room temperature while olive oil is liquid.
a bacterium grows in a cold environment, its membrane must be
fluid, or oily. In a
warm environment, the membrane must be more rigid, what we call
solid or waxy. If a
cell's membrane fails to respond appropriately to temperature
changes, its integrity will be disrupted, and it will die.
for their purposes and mine, cells respond to temperature changes
by altering their chemistry and making different types of lipids.
To convert a wax to an oil, a bacterium removes hydrogen
from the lipid. It adds hydrogen to make the oil more waxy.
back to my surmise: Could we lower the growing temperature of the Acinetobacter
and cause them to answer nature's call and produce an oil rather
than a wax? You wouldn't be reading this unless this surmise succeeded.
Although the organism grows more rapidly at 25˚C, it
yields a jojoba-like oil at 15˚C, an unsaturated lipid with
fewer hydrogen atoms and therefore greater fluidity.
Thus we took advantage of nature's own adaptive mechanism
to "persuade" the bacterium to make the kind of lipid we
this was not the end of the project.
We had to modify the chemistry of the oil to bring its
properties even closer
to those of jojoba oil. To
do this, we had to make sure that we had enough carbon atoms in
the oil so it had the correct solubility.
We experimented with changing the number of carbon atoms in
the material we fed to the bacteria and which it metabolized into
oil--our goal--contains organic esters with 38 to 44 carbon atoms.
Bacteria biochemically synthesize esters by doubling the
number of carbon atoms in the precursor molecule.
Thus, we needed a precursor with approximately 20 carbon
atoms, and it turned out that a particular fraction of
hydrocarbons from crude oil refining had just the right number of precursor carbons.
Fortunately, this material was inexpensive.
growing at 15°C were fed these 20-carbon precursors, they
produced a jojoba-type oil. So
we again allowed nature's know-how and raw materials to influence
our product design and production method.
at that point, our yield was still minuscule, so we used two tacks
to increase it. We
found that the bacterium was enzymatically degrading the oil
immediately after synthesizing it.
We solved that problem by establishing an aqueous (water)
layer and an organic layer in our process chamber.
As quickly as the oil was made, it was extracted into the
organic layer, where it was inaccessible to the problem enzyme.
again we took a tip from nature:
Nutrients are often sequestered in an organic phase; that's
why an oil slick on the ocean is not available to most organisms
in the water. Although
some voracious organisms can attack
those nutrients by producing a surfactant to release them from
the organic phase, our
approach worked because Acinetobacter had not developed that technique.
we boosted the yield of lipid with classical mutation methods.
We used ultraviolet light and various chemicals to induce
large numbers of mutants and found some that produced much more of
the jojoba-like oil than the parent strain.
This method is really the same type of process that
nature has been using through countless eons of evolution.
If the natural mutation increases survival rates, nature
adopts the process. In
industry, if the artificial mutation increases production of the
right materials, companies adopt the mutant.
a chemist, I continually look to nature for clues.
Many of my proudest breakthroughs have started with a look
at what is taking place in nature.
Nature can be a generous partner to the creative scientist.