Investigation of the interactions of bacteria with the oil-water interface

In this study, bacteria with the best and fastest adsorption ability to n-decane were isolated from environmental samples and various physical-chemical and molecular biological parameters and bacterial n-decane/water interface interactions were investigated. For this purpose, 12 bacterial isolates were identified as Pseudomonas putida OW1, Rhodococcus qingshengii OW2, Prescotella equi OW3, Brevibacillus parabrevis OW4, Paenibacillus lautus OW5, Paenibacillus lautus OW6, Moraxella osloensis OW7, Stutzerimonas stutzeri OW8, Stutzerimonas stutzeri OW9, Stutzerimonas stutzeri OW10, Rhodococcus ruber OW11, Rhodococcus erythropolis OW12, which adhered at the n-decane/water interface. Hydrocarbon degradation, bacterial adhesion to hydrocarbon test (BATH), biosurfactant screening analyses (emulsification index test, oil displacement test, CTAB agar plate test), chemotaxis experiment, analyses of degradation and biosurfactant genes, FESEM and Pendant drop visualizations were performed to determine the rheological properties of the biofilm formed at the n-decane/water interface. Hydrocarbon degradation analyses showed that all isolates have ability to degrade n-decane. The highest rate of degradation was 97% and the lowest rate was 79%. It was observed the, OW7 and OW11 isolates are not hydrophobic whereas the other isolates are hydrophobic. Besides, all isolates produced biosurfactant at diverse levels. It was detected that the Pseudomonas genus rapidly adsorbed to the n-decane/water interface and formed stable and elastic biofilms with mobility and chemotaxis experiments. Also, presence of alkB genes which responsible for alkane degradation was detected in all isolates except strain OW1. The presence of genes responsible for trehalolipid production was proved in members of Rhodococcus genus and strain OW7. KEYWORDS: Biodegradation, biosurfactant, oil/water interface, biofilm, chemotaxis, n-decane