Page 110 - Proceeding The 2nd International Seminar of Science and Technology : Accelerating Sustainable Innovation Towards Society 5.0

nd
The 2 International Seminar of Science and Technology
“Accelerating Sustainable innovation towards Society 5.0”
ISST 2022 FST UT 2022
Universitas Terbuka
bacterial cells (Figure. 2a) [17]. The EPS matrix also contains
extracellular deoxyribonucleic acid (e-DNA) [18] [1] [19]. In biofilm,
there are also channels where water, air, or nutrients needed by
bacteria flow [17]. Biofilm formed through quorum sensing mechanism
and transcription of different genes [19].
Quorum sensing is the regulation of gene expression in response to
an increase in the bacterial population. Bacteria communicate through
quorum sensing by secreting chemical molecules called autoinducers.
As the bacterial population increases, the concentration of
autoinducers also increase. Quorum sensing is used as a regulation
of the physiological activities of bacteria, for example, symbiosis,
virulence, motility, conjugation, as well as biofilm formation. Biofilm
formation has several stages including, attachment, transition,
formation and maturation, and the detachment or dispersion stage
(Figure. 2b) [20].
The attachment stage begins when environmental signals induce
bacterial planktonic cells. This signal can be a change in nutrient
concentration, pH, temperature, oxygen, or osmolarity. Bacteria
respond to these signals by attaching to surfaces. Attachment can be
done by flagella, pili, or lipopolysaccharide. Hydrophobicity or the
hydrophobic nature of a surface can also affect the attachment of
bacteria. It is known that bacteria tend to form biofilm on hydrophobic
surfaces. At this early stage, bacterial cells can still easily be
separated from the surface or reversible [20] [21] [19].
The next stage is the transition where the reversible attachment turns
into irreversible, thus the bacteria are not easily separated from the
surface. At this stage the bacteria will divide and form microcolonies.
Bacteria in the microcolonies can communicate with each other
through the quorum sensing mechanism. Quorum sensing causes
bacteria to secrete exopolysaccharides (EPS). EPS will be thickened
so that bacterial motility will be reduced. Bacteria also lose their
flagella, so that planktonic bacteria turn into sessile bacteria [19]–[21].
The next stage is formation and maturation. Bacterial cells continue to
communicate through quorum sensing so that EPS will continue to be

ISST 2022 – FST Universitas Terbuka, Indonesia 89
International Seminar of Science and Technology “Accelerating Sustainable
Towards Society 5.0