Differences in Metabolism between the Biofilm and Planktonic Response to Metal Stress

Abstract

Bacterial biofilms are known to withstand the effects of toxic metals better than planktonic cultures of the same species. This phenomenon has been attributed to many features of the sessile lifestyle not present in free-swimming populations, but the contribution of intracellular metabolism has not been previously examined. Here, we use a combined GC-MS and (1)H NMR metabolomic approach to quantify whole-cell metabolism in biofilm and planktonic cultures of the multimetal resistant bacterium Pseudomonas fluorescens exposed to copper ions. Metabolic changes in response to metal exposure were found to be significantly different in biofilms compared to planktonic cultures. Planktonic metabolism indicated an oxidative stress response that was characterized by changes to the TCA cycle, glycolysis, pyruvate and nicotinate and niacotinamide metabolism. Similar metabolic changes were not observed in biofilms, which were instead dominated by shifts in exopolysaccharide related metabolism suggesting that metal stress in biofilms induces a protective response rather than the reactive changes observed for the planktonic cells. From these results, we conclude that differential metabolic shifts play a role in biofilm-specific multimetal resistance and tolerance. An altered metabolic response to metal toxicity represents a novel addition to a growing list of biofilm-specific mechanisms to resist environmental stress.

Characterization of Pleurotus ostreatus Biofilms by Using the Calgary Biofilm Device

“…These findings are in agreement with other studies reporting that the sessile growth mode might lead to a lower susceptibility to metal ions than the free-living mode (37,46). Thus, in addition to fulfilling the structural criteria suggested by Harding et al (2), P. ostreatus biofilms exhibited a commonly observed hallmark among microbial biofilms, namely, an increased resistance to toxicants compared to the respective free-floating state (2,11). The combined action of chemical, physical, and physiological phenomena is the determinant for the increased tolerance to toxicants of biofilm systems compared to free-living counterparts (37).…”

“…An additional issue to be addressed is whether P. ostreatus biofilms exhibit increased ability to cope with ubiquitous contaminants, such as heavy metals, a common property of microbial biofilms (10,11). Due to the widely reported P. ostreatus ability to degrade a wide array of xenobiotics (8,12), this has important repercussions in the mycoremediation of contaminated sites and wastewater treatment where mixed scenarios of contamination involving inorganic and organic pollutants are often observed (13).…”

Bacterial Community Morphogenesis Is Intimately Linked to the Intracellular Redox State

“…Eukaryotic macroorganisms alleviate this problem in part through (i) internal circulation that allows delivery of substrates to specific locations and (ii) metabolic differentiation. Although the significance of the multicellular lifestyle for metabolism and pathogenicity of microorganisms is well recognized (3)(4)(5), the mechanisms enabling microbial communities to cope with substrate limitation are poorly defined.…”

Bioremediation of agricultural solid waste leachates with diverse species of Cu (II) and Cd (II) by periphyton

“…As the metabolism of the carbon sources is an indicator of the vitality of periphyton (Booth et al, 2011), results from this study implied that the microbial composition of periphyton must have changed to acclimatize to the conditions of waterand Na 2 EDTA-washed leachates and maintain sustainable functions in entrapping a range of Cu and Cd species.…”