Xylene

Bacterial surface hydrophobicity was measured using the bacterial adhesion to hydrocarbon (BATH) assay as described in
Hui & Dykes (2012) (link).
P. aeruginosa culture was collected at stationary phase and pelleted by centrifugation (NF800R, NUVE, Belgium) at 7,000 rpm for 10 min. This pellet was washed twice in phosphate buffer saline (PBS; pH 7.4), and then resuspended in PBS with PGPE (25 and 50 μg/ml) to OD
₇₆₄= 1.00. Same procedure was repeated with
P. aeruginosa culture without PGPE, as a control. Each bacterial suspension was then incubated for 1 h at room temperature. A 2-ml sample of each suspension was collected and absorbance (A) at 764 nm was measured, using PBS as the blank. Next, 1 ml xylene (HiMedia, Mumbai) was added to the 2-ml cell suspension, and this mixture was vortexed for 2 min. The phases were then allowed to separate for 1 h. The absorbance of the aqueous phase (A
₀) was again determined. Results were expressed as % attachment to xylene = (1-A/A
₀) × 100.

Lactobacillus de Man, Rogosa, and Sharpe (MRS) agar and broth, oxgall salt glycerol, phenol, NaCl, xylene, deoxyribonuclease (DNase) agar medium, blood agar medium with 5% (w/v) sheep blood, ABTS, DPPH, and, antibiotic susceptibility disc were procured from HiMedia Laboratories Pvt. Ltd., Mumbai, India. The pathogens namely, Bacillus subtilis MTCC 10403, Escherichia coli MTCC 4430, Pseudomonas aeruginosa MTCC 424, Micrococcus luteus MTCC 1809, and Salmonella typhimurium MTCC 98 were procured from the Microbial Type Culture Collection and Gene Bank (MTCC), Chandigarh, India.

Bacterial surface hydrophobicity was measured using the bacterial adhesion to hydrocarbon (BATH) assay as described by Hui and Dykes [32 (link)]. The P. aeruginosa culture was collected at the stationary phase and pelleted by centrifugation (NF800R; NUVE, Belgium) at 7,000 rpm for 10 min. This pellet was washed twice with phosphate buffer saline (PBS; pH 7.4) and then resuspended in PBS with HF (0.5% v/v) to OD₇₆₄ = 1.00. The same procedure was repeated with the P. aeruginosa culture without HF, as a control. Each bacterial suspension was then incubated for 1 h at room temperature. 2 mL sample of each suspension was collected, and absorbance (A) at 764 nm was measured, using PBS as the blank. 1 mL of xylene (HiMedia, Mumbai) was added to the 2 mL cell suspension, and this mixture was vortexed for 2 min. The phases were then allowed to separate for 1 h. The absorbance of the aqueous phase (A₀) was again determined. The results were expressed as follows: $\begin{array}{c}\%\text{\hspace{0.17em}\hspace{0.17em}attachment\hspace{0.17em}\hspace{0.17em}to\hspace{0.17em}\hspace{0.17em}<a class="product" href="/product/uSjiCZIBPBHhf-iFLWGd/" target="\_blank">xylene</a>}=\left(1-\left(\frac{A}{A_0}\right)\right)\times 100.\end{array}$