Sorption of Streptococcus suis on various soil particles from an Alfisol and effects on pathogen metabolic activity

Abstract

The potential contamination of soil environments by pathogens from agricultural manures has received great attention in recent years. However, few studies of the sorption and metabolic activity of pathogens on soil particles have been conducted to date. In this study, we investigated the sorption of pathogen Streptococcus suis on various soil particles from an Alfisol as a function of pH and calcium chloride (CaCl2) concentration. S. suis metabolic activity in the presence of different soil particles was also studied by micro‐calorimetric techniques. The amount of S. suis sorbed followed the order: inorganic clay > organic clay > inorganic silt > organic silt > inorganic sand > organic sand. Zeta potentials of S. suis were negative over the experimental conditions and increased with the decrease of pH or the increase of Ca2+ concentrations. A gradual decrease in the sorption of S. suis on soil particles was observed with the increase of pH from 4.0 to 9.0. Increasing Ca2+ concentrations (0–1 mm) resulted in an increase of S. suis sorption on clays, silts and sands, while larger Ca2+ concentrations (20–50 mm) depressed S. suis sorption on silts and sands. The exponential growth of S. suis was stimulated by silts and sands, but inhibited by clays. Our results show that electrostatic forces play a major role in the sorption behaviour and that an additional non‐DLVO type interaction (electrosteric repulsion) occurs at large Ca2+ concentrations. Different sorption affinities of S. suis on soil particles may be the dominant factor influencing S. suis activities.

Interactions BetweenEscherchia coliand the Colloids of Three Variable Charge Soils and Their Effects on Soil Surface Charge Properties

“…The adhesion of E. coli to soil colloids decreased with increasing pH, which agreed with previous studies (Wu et al 2011a;Zhao et al 2012a). Zhao et al (2012a) found that the adhesion of S. suis to soil particles decreased as the pH rose from 4.0 to 9.0.…”

“…Zhao et al (2012a) found that the adhesion of S. suis to soil particles decreased as the pH rose from 4.0 to 9.0. Wu et al (2011a) also observed that P. putida adhesion to soil particles was reduced by 44.0-78.8% when the pH was increased from 4.0 to 9.0.…”

“…The presence of organic matter usually inhibits the adhesion of bacterial cells to soil particles (Mills 2003;Guber et al 2007;Wu et al 2011a). Zhao et al (2012a) found that the amount of S. suis adhered by soil particles followed the order: inorganic clay > organic clay > inorganic silt > organic silt > inorganic sand > organic sand. Furthermore, low-molecular-weight (Wu et al 2011b).…”

Contrasting effects of extracellular polymeric substances on the surface characteristics of bacterial pathogens and cell attachment to soil particles

“…coli and full EPS-S. suis remained constant (P N 0.05), while only the full EPS-E. coli increased slightly by 3.2 mV. This result suggests that the compression of the double layer is effectively achieved around 60 mM (Mills et al, 1994;Zhao et al, 2012). Similar results were also observed in literature that the zeta potentials of E. coli O157:H7 and Salmonella pullorum SA1685 were unchanged (P N 0.05) at high IS conditions (Castro and Tufenkji, 2007;Haznedaroglu et al, 2009).…”

Soil Interfaces in a Changing World

“…These phenomena are important to understand the fate of pathogens in terms of immobilization and metabolic activity, especially if these are responsible for serious diseases of animal and humans. Zhao et al (2012) focused specifically on the sorption of Streptococcus suis on various soil particles, and effects on the metabolic activity of the sorbed pathogen. Sorption of this microorganism was greater on clay particles, with little effect of organic matter coatings, and depended especially on electrostatic forces and electrosteric effects at large Ca 2+ concentrations.…”