소수성에 따른 박테리아 부착과 이론적 접근법의 적용성 평가 = Bacterial Adhesion based on Hydrophobicity and Assessment of Applicability of Theoretical method

다국어 초록 (Multilingual Abstract)

Bacteria tend to attach and cluster easily to surrounding surfaces to form microbial communities and biofilm. This is a survival strategy used by nearly all bacteria and is known to increase its own viability through the formation of biofilm and spread to the surface. Depending on the field of application, it can be both beneficial and problematic. Therefore, it is important to selectively control microbial adhesion. To do this, studies on the surface properties of bacteria surfaces and material surfaces are needed. This can be used as a basis for research that optimizes or minimizes conditions to form bacterial adhesives. Initial adhesion is affected by various physicochemical factors of both bacteria and surfaces, best known is hydrophobicity and surface charge. The adhesion of four bacterial strains (Escherichia coli EC, Bacillus licheniformis BC, Pseudomonas aeruginosa PS and Staphylococcus aureus SA) to the glass and the Polypropylene(PP) surfaces was investigated. The aim of this study was to evaluate the applicability of the DLVO and XDLVO theory to predict adhesion and study the effect of the hydrophobicity on bacterial adhesion to surfaces. The hydrophobicity of the bacteria and materials was measured using CAM(Contact angle measurement). The hydrophobicity results
of water contact angle measurement showed that the BL is relatively hydrophilic than other bacteria. For both materials, this angle was 5° for glass and 88° for PP. It has been demonstrated for use as a hydrophilic/hydrophobic surface experiments. DLVO and XDLVO results showed that bacteria will
adhere to the PP surface better than the glass because there is a section where △ G has a negative value in the PP, while the glass has a positive value which means that the bacteria do not adhere well or develop weakly. When prediction results through DLVO and XDLVO theory and adhesion test results were compared, they were matched well with the measurement time except for BL. In the case of BL, it adhered well to PP only in the first 30 minutes, and after that, it adhered to glass more. When the adhesion results are summarized, it can be seen that the hydrophobic bacteria adhere to the hydrophobic surface and the hydrophilic bacteria adhere to the hydrophilic surface better. In this experimental condition, compared to DLVO and XDLVO,
there was no significant difference in the prediction, and it was matched well with the adhesion result, so it is considered that there will be no difficulty in predicting which one will be used. DLVO and XDLVO theory is feasible for predicting initial adhesion and controlling the bacterial adhesion which are important in bioprocess, but chemical and biological properties need to be considered to achieve prediction of next stages.

목차 (Table of Contents)

• 1. 서론 1
• 1.1 연구배경 1
• 1.2 연구목적 및 가설 3
• 2. 문헌연구 4
• 2.1 박테리아 부착(Bacteria adheison) 4
• 2.1.1 표면 전하(Surface charge) 5
• 2.1.2 소수성(Hydrophobicity) 7
• 2.2 소수성 측정 9
• 2.2.1 CAM(Contact angle measurement) 9
• 2.2.2 접촉각 11
• 2.2.3 표면에너지 12
• 2.3 박테리아 부착 이론적 모델 15
• 2.3.1 열역학적 접근법 15
• 2.3.2 DLVO theory (DerjaguinLandauVerweyOverbeek) 18
• 3. 연구방법 21
• 3.1 박테리아 선정 및 배양 조건 21
• 3.1.1 박테리아 선정 21
• 3.1.2 박테리아 배양 조건 23
• 3.2 부착 표면 선정 및 준비 24
• 3.2.1 부착 표면 선정 24
• 3.2.2 부착 표면 준비 24
• 3.3 Hydrophobicity(소수성) 측정 25
• 3.4 Adhesion test(표면에 대한 박테리아 부착 실험) 26
• 4. 연구 결과 27
• 4.1 소수성 및 표면 에너지 측정 결과 27
• 4.1.1 박테리아 소수성 및 표면에너지 27
• 4.1.2 부착표면 소수성 및 표면에너지 30
• 4.2 DLVO & XDLVO 예측 결과 32
• 4.3 박테리아 부착 결과 43
• 5. 결론 46
• 참 고 문 헌 48