FACTORIAL ANALYSIS ON BACILLUS SP. REMOVAL USING GARLIC SOLUTION

Abstract

Biofilm is a microbial derived sessile community characterized by cells that are

irreversibly attached to a substratum or interface to each other, embedded in a matrix of

extracellular polymeric substances that they have produced. Many different microbes

can be found in biofilm such as Bacillus sp., Listeria monocytogenes, Staphylococcus

sp., Escherichia coli and many more. Bacillus sp. was used as biofilm model in this

study. The purpose of this study is to determine the most affecting factors in Bacillus sp

removal. Garlic solution was used to remove Bacillus sp. In this study, garlic solution

was prepared by crushing the garlic and mixed it with water. Bacillus sp. was mixed

with nutrient broth before it was incubated. Then, the garlic solution was added into

Bacillus sp. mixture and mixed well. The mixture then was spread on nutrient agar. The

Bacillus sp. weight on agar plate was measured by using dry weight measurement

method. The selected factors were ratio of water to garlic (W/G) (1:1 and 1:5), ratio of

garlic solution to Bacillus sp. (GS/B) (1:1 and 1:3), agitation speed (50  – 100 rpm) and

reaction time between Bacillus sp. and garlic (12  – 24 hours). Design Expert software

(Version 7) was used to construct experimental table where all the factors were

randomized. The most contributing factor and interaction between the factors was

analyzed via two level factorial analysis by using the same software. The results showed

that the most significant factors were GS/B and agitation speed, while for the interaction

effect was between W/G and GS/B. The Bacillus sp. removal best condition was

determined at W/G at 1:1, GS/B at 1:3, agitation speed at 50 rpm and reaction time at 12

hours. The result of the best condition was 88.46% of Bacillus sp. removal.