The water cooling system is one of the most important units in the
industry. This is because in the cooling system, a heat exchange process
occurs to lower water temperature caused by overheating which can
result in decreased effectiveness and damaged machinery in
manufacturing. However, temperature alteration and organic matter in
water cooling systems can support the growth of microbes such as
biofilm-forming microbes. The biofilm formed in the cooling water
system can accelerate biocorrosion, therefore a compound that can
inhibit and eradicate the forming of biofilms is needed. Biosurfactant is
one of the potential compounds that can be used to eradicate biofilms
because it has anti-adhesion, and anti-biofilm activity, is easily
degradable, non-toxic, and can be used over a wide range of conditions.
Therefore, this study aims to determine the activity of biosurfactant F7
as an anti-adhesion and anti-biofilm on gram-positive and gram-negative
bacterial biofilms by determining the MBIC and MBEC values and their
effect on the corrosion rate of Carbon Steel ST 37. This research was
conducted by constructing a biofilm formation curve from single
cultures of isolates 1 (gram-positive bacteria) and 5 (gram-negative
bacteria) on Carbon Steel ST 37 with general medium Nutrient Broth. In
addition, the activity of biosurfactant F7 as an anti-biofilm was
determined by determining the value of MBIC and MBEC on biofilm
isolates 1 and 5. The MBIC and MBEC values were determined by
measuring the wet weight of the biofilm formed. Meanwhile, the steel
corrosion rate was carried out by measuring of the decrease in steel mass. The results of this study indicate that the maturation time of
biofilm is 6 days for gram-positive bacteria and 3 days for gramnegative
bacteria. In addition, the MBIC and MBEC values of
biosurfactant F7 were 28.5 ppm and 570 ppm. After being given
biosurfactant treatment with 28.5 ppm concentration, the corrosion rate
of Carbon Steel ST 37 which was incubated by isolates 1 and 5 showed
a decrease of 0.02321 mm/year and 0.01547 mm/year if compared to the
untreated control. Meanwhile, the addition of the biocide glutaraldehyde
as much as 0.5% (v/v) caused the corrosion rate of 0.02063 mm/year
and 0.00773 mm/year. Therefore, based on this study, it can be
concluded that F7 biosurfactant is more effective in inhibiting
biocorrosion on Carbon Steel ST 37 when compared to glutaraldehyde.