A Multi-Scale Approach to Investigate Adhesion Properties of Pseudomonas aeruginosa PAO1 to Geotrichum candidum LG-8, a Potential Probiotic Yeast.

Dian Li,Ling Meng,Fangxin Lyu,Mingsheng Dong,Siduo Zhou,Xiao Xu,Yanfei Lin

doi:10.3390/foods9070912

Abstract

This study investigated properties of Pseudomonas aeruginosa PAO1 adhesion to Geotrichum candidum LG-8 cells in variable pH and salt conditions. The primary mechanism was revealed by multi-scale microscopy technics. The adhesion of PAO1 to the living fungus occurred within 1 h and was limited at concentrations of bile salts higher than 0.5%. The adhesion efficiency gradually increased to 58.1% with the pH increasing from 2.0 to 7.0 and then decreased to 48.2% at pH 9.0. However, the dead LG-8 has an advantage over the living ones to adhere PAO1 in same pH and bile salt conditions. Optical microscopy showed that both unsterilized and sterilized G. candidum LG-8 cells removed approximately one hundred fold bacteria in 4 h. Laser scanning confocal microscopy (LSCM) analysis indicated that polysaccharides of the fungus contributed to adhesion. Scanning electron microscopy (SEM) analysis proved that syrup-like EPS (extracellular polymeric substances) of LG-8 coating PAO1 was in part a mechanism. Atomic force microscopy (AFM) showed roughness of the LG-8 surface changed in the adhesion process. Furthermore, a pedestal-like structure of bacteria was observed by transmission electron microscopy (TEM) analysis, indicating that the bacteria were also actively involved in the adhesion process. G. candidum LG-8 is a potential candidate for the control of P. aeruginosa PAO1 in the food industry and immunodeficiency patients.

Highlights

Pseudomonas aeruginosa is a common foodborne and waterborne pathogenic bacterium
The adhesion of P. aeruginosa PAO1 to the fungal LG-8 occurred in a very short time (1 h), indicating that adhesion of PAO1 to the surfaces of LG-8 cells was a mechanism of trapping PAO1 by LG-8 cells
G. candidum LG-8 efficiently traps P. aeruginosa PAO1 over wide ranges of oxgall bile salt concentrations and pH values. It indicated that G. candidum LG-8 is a potential probiotic candidate

Summary

Introduction

Pseudomonas aeruginosa is a common foodborne and waterborne pathogenic bacterium. It can cause spoilage of food by consuming the nutrients in food and/or producing certain molecules [1].According to the World Health Organization (WHO), 70% to 80% of human diseases are caused by unclean drinking water. Pseudomonas aeruginosa is a common foodborne and waterborne pathogenic bacterium. It can cause spoilage of food by consuming the nutrients in food and/or producing certain molecules [1]. According to the World Health Organization (WHO), 70% to 80% of human diseases are caused by unclean drinking water. With the improvement of living quality, water quality has attracted consumers’. Reports of P. aeruginosa detected in packaged drinking water are increasing, indicating a direct threat to consumer health [2,3]. P. aeruginosa is a common opportunistic human pathogen that rarely poses a threat to healthy individuals. It poses a major threat to immunocompromised individuals and cystic fibrosis patients with underlying conditions [4]

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