Nitrogen starvation affects bacterial adhesion to soil

Abstract

One of the main factors limiting the bioremediation of subsoil environments based on bioaugmentation is the transport of selected microorganisms to the contaminated zones. The characterization of the physiological responses of the inoculated microorganisms to starvation, especially the evaluation of characteristics that affect the adhesion of the cells to soil particles, is fundamental to anticipate the success or failure of bioaugmentation. The objective of this study was to investigate the effect of nitrogen starvation on cell surface hydrophobicity and cell adhesion to soil particles by bacterial strains previously characterized as able to use benzene, toluene or xilenes as carbon and energy sources. The strains LBBMA 18-T (non-identified), Arthrobacter aurescens LBBMA 98, Arthrobacter oxydans LBBMA 201, and Klebsiella sp. LBBMA 204–1 were used in the experiments. Cultivation of the cells in nitrogen-deficient medium caused a significant reduction of the adhesion to soil particles by all the four strains. Nitrogen starvation also reduced significantly the strength of cell adhesion to the soil particles, except for Klebsiella sp. LBBMA 204–1. Two of the four strains showed significant reduction in cell surface hydrophobicity. It is inferred that the efficiency of bacterial transport through soils might be potentially increased by nitrogen starvation.

Implications of Growth and Starvation Conditions in Bacterial Adhesion and Transport

“…4(a)). Similar results of decreasing hydrophobicity with starvation duration have been reported [25,28,46,48,49,72]. Opposite trends, i.e., hydrophobicity increase with longer starvation durations were observed for Enterococcus faecalis [47], Aeromonas hydrophila [73], Vibrio parahaemolyticus [50] and E. coli from sewage [27].…”

“…Important aspects of biofilm formation are the initial adhesion as well as propagation (growth), both of which are functions of nutrient availability, namely growth and starvation conditions. These parameters, in turn, affect bacterial properties including cell hydrophobicity, size and biomass [7,[25][26][27][28][29][30][31][32][33]66]. While it is known that bacteria have excess nutrients in food and dairy industries, human and animal bodies, water treatment and bio-augmentation systems, they have to contend with substrate deficiency in distribution pipes, surface and subsurface flow, microbial enhanced oil recovery (MEOR), etc.…”

“…Growth and starvation conditions have been reported to lead to changes in cell size, protein content, hydrophobicity and biomass [25][26][27][28][29][30][31][32][33]. The same parameters have also been examined as significant factors for microbial adhesion and transport [34][35][36].…”

“…In fact, hydrophobicity is often considered critical for initiating bacterial adhesion through non-specific interactions and hydrophobic interactions represent the strongest long-range non-covalent interactions [37][38][39][40][41]. Hydrophobicity has also been studied as a crucial parameter for bioremediation potential of a number of bacterial strains capable of metabolizing organic solvents [25,[42][43][44]. Since bacterial adhesion is a crucial component of the biofouling initiation and propagation, the factors affecting it assume significance.…”

Retention in Treated Wastewater Affects Survival and Deposition of Staphylococcus aureus and Escherichia coli in Sand Columns

“…Within the current body of literature, little attention has been paid to the fate of waterborne pathogenic microbes under nutrient-deficient conditions that prevail in the natural environment and wastewater treatment facilities (17,(22)(23)(24). Walker reported that, for both Burkholderia cepacia G4g and ENV435g, the deposition rates for cells cultivated in nutrient-rich medium differed from those in nutrient-poor basal salt medium (17).…”