Biofilms are highly structured communities of bacteria that attach to surfaces and secrete an extracellular matrix. Within biofilms, bacteria communicate chemically through quorum sensing and are much more resistant to antibiotics than individual bacteria. This makes biofilms a major cause of persistent infections associated with medical implants and devices. Researchers are working to develop new treatments that target biofilm formation and quorum sensing, with some looking at natural compounds that inhibit these processes. Proper testing models are still needed, as bacteria in biofilms may differ significantly from individual bacteria and assumptions that they are similar could lead to problems.

1. POPULAR SCIENCE SUMMARY ON ‘Slimy business -
The Biotechnology of Biofilms’
NAME: ISHMAM NAWAR
ID: 081510047
FACULTY: SDL

2. Slimy business - The Biotechnology of Biofilms
Bacteria are more anthropoid in nature than we thought they were, at least from a sociologist’s
point of view. Just like we tend to end up clinging in a community rather than settle for a
hermetic life, these little microbes are being discovered to do the same thing too. In fact, not only
do they stick together in what the scientists call a “biofilm”, they have put on a notorious edge to
their communal way of life as well!
What are Biofilms?
On a more stricter definition, biofilms are the highly structured living arrangements of bacteria (
or other microbes) that forms the slime layer we so often see forming on medical implants and
other hydrated surfaces. An analogy can be made between the biofilm and a city because within
the biofilm there is division of labor and mutual living (i.e. bacteria live off each others waste-
products and productions.) They attach to each other and to the solid support by excreting a
substance called EPS (extracellular polymeric substance) that forms a sticky matrix. Often, there
are more than one species colonizing one biofilm. For example, the yellowish layer on our teeth
called dental plaque carries over 400 different bacterial species. As gross as it might sound, these
little folks have developed fantastic ways to make sure we do not harm their existence or brush
them out of our teeth!
Microscope view of dental plaque.
Microscope view of a biofilm in the nozzle of a The plaque consists of over
dentist’s instrument used to clear away drilling 400 different species of bacteria.
debris in a patient’s mouth.

3. The composition of the slimy layer differs depending on the species of organism involved. Gram
negative bacteria makes neutral or polyanionic biofilms whereas Gram positive bacteria produce
cationic ones. Other adjuvants might effect the stability of the layer, for example metal ions can
cause better cross-linking and hence, stickier and stabler matrix of polyanionic EPS. On the other
hand, lactoferrin, an iron binding protein in mammals prevents P.aeruginosa from forming
biofilms.
Such convivial conglomerates of microbes do more than just stick to surfaces. In fact, they
communicate with each other through chemical signaling. When enough of the chemical has
accumulated, it means that there is enough microbes to commence the formation of biofilm. The
microbes then start changing their lifestyles to suit living in a community than living separately.
The process of chemically sensing the population density is called Quorum sensing. Quorum
sensing forms the basis for many anti-biofilm drug designers as disrupting Quorum sensing can
inhibit communication and thus, biofilm formation.
Fig. 1: The biofilm life cycle. 1: individual cells populate the surface. 2: extracellular polymeric
substance (EPS) is produced and attachment becomes irreversible. 3 & 4: cells become layered
and effects of quorum sensing begins. 5: cluster reaches maximum thickness and single cells are
released from the biofilm
The biofilm problem
The proverb “Unity is Strength” probably never had such a negative connotation as it does while
describing biofilms. United, the microbes in the biofilm defend against their killers (antibiotics):
they employ mechanisms to destroy antibiotics, build up impenetrable bastion so that the
microbes’ demons can’t reach them.
Once in biofilm, bacteria can be several folds more resistant to antibiotics than when they live
freely. This could be due to one of the following reasons:

4. 1. Most antibiotics kill rapidly dividing cells. This works for normal bacterias because they
have a very fast rate of reproduction ( e.g. they double every 20 minutes). However, in
biofilms, bacteria replicate much more slowly. So the antibiotic might not be effective
here.
2. The thick sticky matrix is difficult for the drug to penetrate.
3. Some bacteria adapts and changes their outward appearance to protect themselves from
the action of antibiotics
4. In the biofilm are regions where nutrients and waste products of the community collect. If
antibiotic reaches that part, it might be destroyed.
5. The bacteria might change from inside genetically. Certain genes are switched on that
makes them insensitive against the antibiotic.
Whatever the reason, antibiotic resistance of biofilms are a huge concern for people in the
medical and research arena. Biofilms on catheters, pacemakers, artificial joints can lead to deadly
infections. In fact, The National Institute of Health estimated that biofilms cause over 80% of
infections. According to the Biomedical Market Newsletter, catheter related bloodstream
infections solely can cause increased mortality, longer stays in hospitals and increased medical
cost ( around $6000 more per patient). Most of the circulatory and urinary tract infections that
we see are probably due to devices inserted inside our body that harbors biofilms.
Scientists are still to catch up on the varied aspects of biofilms. This is mostly because so far,
research was focused more on the free- living microbes rather than on the community.
Researchers typically use single-celled (planktonic) microbes as experimental models because
they are easy to study and manipulate. Too preoccupied with the “lonely” mode of bacterial
lifestyle, scientists have either overlooked or ended up with devastating consequences where
they mistook planktonic bacteria to be similar to biofilmic ones. After heart valve replacement
operations, many patients developed infection and eventually died out of a condition called
endocarditis. St. Jude Medical, a medical device company, developed a silver coating to prevent
formation of biofilms. However, it was seen that patients with silver coated device had more
infection than patients with uncoated device. This huge disaster occurred simply because the
manufacturers used stuff that would kill free living bacteria rather than those in biofilms.
P.aeruginosa is the most thoroughly studied bacteria because it is the most common cause of
hospital acquired infection. S.epidermis is the species that causes long and short term infections

5. associated with transdermal devices ( devices that need to penetrate the skin). Fungal biofilms
are also being studied recently.
Investing in Biofilms
As bacteria enjoy their shelter within biofilms, our scientists are certainly not going to sit around
watching them make happy families within pace makers. With increasing knowledge on
bacterias’ communal way of life, many biotechnology companies have evolved to research and
develop biofilm related products. The following are some of the companies that are researching
on biofilms and their main approach in short:
● Quorum Sciences: They screen for chemicals that inhibits quorum sensing or biofilm
formation
● Quorex: AI-2 is a chemical that communicates between microbes. If communication can
be inhibited, biofilm formation can be disrupted. Quorex is trying to develop inhibitors of
AI-2
● Microbia: In a biofilm, certain genes of microbes are more actively expressed. Therefore,
these genes must have some connection in developing resistance. Microbia developes
chemicals that works against these genes. Also, they try to sensitize bacteria against
antibiotics.
● Antex: They screen compounds for prevention and disruption of biofilms
Some natural products have been seen to inhibit biofilm formation. Delsea pulchra is a red algae
found in Australia’s Botany Bay. These algae synthesizes organic compounds called furanones
with chlorine or bromine attached that wards off bacterial biofilms.
● Biosignals: They have identified 200 structures similar to the halogenated furanone and
are evaluating each as a potent biofilm disrupter. The mechanism of action of these
furanone analogs is that they interfere with AHL action ( AHL is a signal in bacteria that
causes them to aggregate together and glow. Biofilm formation also requires AHL
signaling). Compounds inhibiting AI-2 dependent quorum sensing have also been
identified.
● Sequoia: They screen plant materials in search of biofilm inhibitors and disruptors.

6. Bioremediation – biofilms to the rescue
By now, the word biofilm probably has become synonymous with “ slimy terrors” and it is truly
so. Its resilient nature toward antibiotic and its infective nature is the cause of headaches of
many. However, biofilm can have its share of usefulness too.
Bioremediation is the process of cleaning up wastes with the use of biological entities. The very
nature of bacteria “ clinging” together in a biofilm can be of immense help in bioremediation.
For example if an area is contaminated with excess fertilizer, biofilms are encouraged to form
underground by adding nutrients. The biofilm forms a “biobarrier” that restricts the flow of
contaminated water through that region and also destroys excess nitrogen in the water. Similar
strategy can also be used to enhance oil recovery. Oilfields no longer in use can be “plugged” off
by encouraging biofilm growth and hence water can be redirected to regions that have untapped
oil. Using sulfate-reducing bacteria in a biofilm, the biofilm can be used for mine remediation.
The bacteria will “eat” up the metals in the contaminated water and precipitate metal sulfides.
Therefore, from a different angle, biofilms can serve as our “community of laborers”. They can
be made to work for cleaning up crude oil, jet fuel, environmental pollutants, etc.
Conclusion/ Critique
In this era, where we are already facing a crisis of effective antimicrobial agents, comes another
new dimension to this problem: Biofilms.The slimy layer, that forms on many hydrated surface,
pose significant threat to human health due to its resistance to antibiotics. Thus, it is of no
wonder that a big share of hospital acquired infections are attributed to these biofilms. More
deadly are the biofilms that grows on surfaces of pacemakers and other implants. Research of
biofilm structure has revealed the formation of a matrix whose composition varies from species
to species. Various chemical signals are used for inter and intra microbial communications. Of
prime importance is the Quorum sensing mechanism that utilizes signals such as AI-2 and AHL.
It is only recently that biotechnology firms have started to acknowledge the problems of
biofilms. They are trying out different strategies to discover novel antibiotics that are effective
against the biofilms. Strategies include prevention of biofilm formation, develope drugs to treat
existing biofilms or try and disrupt the polymeric ties that bind the biofilms together.Many firms
that deal with biofilms aim mostly at quorum sensing mechanisms to inhibit biofilm growth or
formation. Natural inhibitors of biofilms have also been discovered like the halogenated
furanones of red algae.

7. From algal metabolite to Pseudomonas drug. (A) Compound 2, a natural furanone compound isolated
from (C) D.pulchra. (B) compound C-30, a synthetic furanone with enhanced Quorum Sensing Inhibition
activity.
However, before conclusive research, it is very important to make a good model for testing
antibiofilm drugs. Biofilms are certainly more dynamic than scientists so far have discovered.
The volume of data that accumulates each day makes it difficult to settle for an appropriate
model. For example, P.aeruginosa that was always known to be a aerobic microbe turned out to
be anaerobic in biofilms in the lungs of cystic fibrosis patients. According to Roberto Kolter, to
assume that surface associated bacteria grown in synthetic medium in a flow cell in vivo are
physiologically similar to surface associated bacteria growing on any specific site within the host
is rather funny and irresponsible. Therefore, proper models and right parameters is the key to
valid results. If a product is formulated, it should be applied to actual biofilms in actual
environment. Rather than jumping on to formulating drugs, they should converge in discovering
the biofilm’s nature in more details first. In no way should a species that exist in biofilm be
thought to be similar to its planktonic counterpart. Or else, we will again see the repetition of the
heart-valve disaster.