Cell Surface Hydrophobicity Of Bacteria Research Articles

The use of organic peroxyacids for the inactivation of calcium-mediated biofilm formation by Bacillus licheniformis

Biofilms formed by Bacillus licheniformis usually serve as a continuous bacterial contamination in the dairy industry. The purpose of this study was to explore how 1% organic acids (citric acid, phenyllactic acid, malic acid, and butyric acid) and their 1% organic peroxyacids (peroxycitric acid, peroxyphenyllactic acid, peroxymalic acid, and peroxybutyric acid) can inactive the planktonic and biofilm cells of B. licheniformis. Results demonstrated that the number of B. licheniformis planktonic cells was increased from 4 to 6.46 Log CFU mL−1 when treated with water. Organic peroxyacids, especially peroxyphenyllactic acid (PPA), obviously inactivated planktonic cells of B. licheniformis by a range of 3.32–4.14 Log CFU mL−1. Moreover, organic peroxyacids could also decrease the cell surface hydrophobicity of bacteria, and effectively control the Ca2+-mediated biofilm formation by B. licheniformis in 96-well plates (reduction of OD values by 0.14–0.33) and on stainless steel (reduction of cell counts by 1.20–2.49 Log CFU cm−2). The low minimum biofilm eradication concentration of PPA (0.125%) also suggests its strong biofilm inactivation activity, which could serve as a novel and environmentally friendly biofilm control agent in the dairy industry.

10.4314/cajeb.v3i1.37959

Environmental factors may greatly influence the expression of cell surface components of bacterial pathogens. Few studies have described the effect of growth conditions on the cell surface hydrophobicity of bacterial isolates of certain Gramnegative and Gram-positive bacteria. The present study describes the effects of CUltivation in four common liquid growth media on the cell surface hydrophobicity of non-clinical Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus using the microbial adhesion to hydrocarbon (MATH) test which assesses the partition of bacterial cells into a hydrocarbon phase. It was observed that growth in all the test media yielded cells with varying surface hydrophobicity increasing in the order: nutrient broth<tryptic soy broth<brain heart infusion broth<MacConkey broth, irrespective of the test strain. The changes were however, more pronounced in the Gram-positive strain. It was also observed that the surface of Staphylococcus aureus was more hydrophobic than that of Escherichia coli , irrespective of the cultivation media. The outcome of this work further point to the fact that environmental changes can influence cell surface hydrophobicity of bacteria which in turn can affect their adhesion to certain kinds of host targets through hydrophobic interactions. Key words : Hydrophobicity; Escherichia coli; Staphylococcus aureus; Growth media

Application of Biosurfactant from Sphingobacterium spiritivorum AS43 in the Biodegradation of Used Lubricating Oil

This study aimed at investigating the application of biosurfactant from Sphingobacterium spiritivorum AS43 using molasses as a substrate and fertilizer to enhance the biodegradation of used lubricating oil (ULO). The cell surface hydrophobicity of bacteria, the emulsification activity, and the biodegradation efficiency of ULO were measured. The bacterial adhesion in the hydrocarbon test was used to denote the cell surface hydrophobicity of the used bacterial species. The results indicate a strong correlation between cell surface hydrophobicity, emulsification activity, and the degree of ULO biodegradation. The maximum degradation of ULO (62 %) was observed when either 1.5 % (w/v) of biosurfactant or fertilizer was added. The results also revealed that biosurfactants alone are capable of promoting biodegradation to a large extent without added fertilizer. The data indicate the potential for biosurfactant production by using low-cost substrate for application in the bioremediation of soils contaminated with petroleum hydrocarbons or oils.

Effect of Antibiotics on Cell Surface Hydrophobicity of Bacteria Causing Orthopedic Wound Infections

Background: Despite antibiotic prophylaxis and treatment, the incidence of wound infections in orthopedic surgery is significant. Postoperative wound infection is a multifactorial process, which can be modified by several bacterial factors. Cell surface hydrophobicity of bacteria is a very important physicochemical feature, which has a great influence on the ability of bacteria to adhere to the surface of host cells or medical implants. Methods: In this study, the hydrophobic properties of thirteen bacterial strains (coagulase-negative staphylococci, Staphylococcus aureus and Pseudomonas aeruginosa) isolated from patients with postoperative deep wound infections following orthopedic procedures were determined by the salt aggregation test. Results were compared to the hydrophobicity of three Hungarian standard bacterial strains. The modifying effect of four antibiotics (cefuroxime, cefotaxime, amoxicillin combined with clavulanic acid and amikacin) – applied most often in our Department for prophylaxis and treatment of patients – were analyzed. Results: The cell surface hydrophobicity of certain strains showed considerable changes after antibiotic treatment. These alterations indicated the decrease in hydrophobicity. Supra-inhibitory concentrations (2× minimum inhibitory concentrations, MIC) of the antibiotics were able to induce more frequent alterations in hydrophobicity than sub-inhibitory (0.5× MIC) levels. Conclusions: Alterations in cell surface hydrophobicity caused by antibiotics can modify the adhesion process and thus the pathogenicity of bacterial strains. These changes should be taken into consideration in the management of proper antibiotic prophylaxis and in the treatment of orthopedic patients.

Cell surface hydrophobicity of dental plaque microorganisms in situ.

The cell surface hydrophobicity of bacteria obtained directly from human tooth surfaces was assayed by measuring their adherence to liquid hydrocarbons. Fresh samples of supragingival dental plaque were washed and dispersed in buffer. Adherence of the plaque microorganisms to hexadecane, octane, and xylene was tested turbidimetrically and by direct microscopic observation. The results clearly show that the vast majority of bacteria comprising dental plaque exhibit pronounced cell surface hydrophobicity. These data support the hypothesis that hydrophobic interactions play a major role in mediating bacterial adherence on tooth surfaces.