Pseudomonas aeruginosa is one of the Gram-negative rod-shaped bacterium producing biofilms which is an important role in acute and chronic infection. Pseudomonas aeruginosa has an ability to form biofilm. Biofilm formation causes resistant to antibiotics and the body's immune defense system so difficult to eradicate. Biofilm is formed and attached to the surface because of the pathogenic bacteria synthesize extracellular matrix consisting of a polymeric substance (EPS). The aims of the research were to study the pH of the medium which affect the formation of biofilms and analyze the effect of antibiotics against biofilms.

The study began in August to December 2018, using the bacterium Pseudomonas aeruginosa coming from hospital, The research began with growing a pure culture of Ps. aeruginosa in Nutrient Broth liquid medium with a level of acidity (pH) varies 4, 7, and 8 for biofilm formation; Amoxicilin and influence the activity of antibiotics against biofilms tested Viccillin Ps. aeruginosain medium Mueller Hinton Agar (MHA) using Kirby Bauer method.

Results showed that Pseudomonas aeruginosa, Gram-negative rod-shaped, motile and aerobic are not able to grow to form biofilm in acid medium (pH 4) and grow to form a biofilm on the surface of liquid medium with pH 7-8

Table 1, Effect of pH Against Biofilm Formation of Ps. aeruginosa

Nutrient Broth Medium

sample

pH Medium

4

7

8

50%

1

-

+

++

2

-

+

++

Control

 

-

-

-

100%

1

±

+

++

2

±

+

++

Control

 

-

-

-

 

Figure 1. Pseudomonas aeroginosa resistance to antibiotics.

Activities Ps. aeruginosa to form biofilms is inhibited by Amoxicilin and Viccillin. The formed biofilm showed the ability to defend itself against those antibiotic activities as indicated by the wide variety of clear zones; with an average diameter at pH 7 of 2.3 - 10.7 mm and at pH 8 of 4.7 - 15.3 mm, respectively.

The conclusion is the pH of the medium affects the growth and biofilm formation Ps. aeruginosa. Pseudomonas aeruginosa biofilms forming on a medium that tends to alkaline pH, which is pH 7 and pH 8. Bioflm Ps. aeruginosa formed on the alkaline pH of the medium that tends to be resistant to the antibiotic Amoxicillin than Viccillin indicated by the wide variety of clear zones.

Keywords: Pseudomonas aeruginosa, a biofilm, biofilm resistance, Amoxicillin and Vicillin.