Implications of microbial adaptation for the assessment of environmental persistence of chemicals

Abstract

Persistency of organic chemicals is a key property in their environmental risk assessment. Information on persistency is often derived from the results of biodegradability screening tests such as the ready biodegradability tests (RBTs). RBTs are, however, not designed for this purpose and suffer from several problems that lead to a high variability of the results and, hence, to difficulties in their interpretation. The origin and exposure history of the inocula used for biodegradability testing can lead to highly variable outcomes. Microbial adaptation to chemicals and its impact on biodegradation needs further investigation in order to have a better understanding of their effects on persistency assessments of chemicals. It is well described that microbial adaptation stimulates biodegradation of organic chemicals. Several mechanisms responsible for these phenomena have been described, amongst which are i) shifts in community composition or abundances, ii) mutations within populations, iii) horizontal gene transfer or iv) recombination events. These adaptation processes may well be mimicked under laboratory conditions, but the outcome remains difficult to predict as we lack a fundamental understanding of the adaptive responses. This review aims to bring together our current knowledge regarding microbial adaptation and its implication for the testing of biodegradation of chemicals. Abbreviations BHRBroad host range plasmid HGT

A review of the nature, role and control of lithobionts on stone cultural heritage: weighing-up and managing biodeterioration and bioprotection

“…Although many of the more toxic biocides have been banned, safer compounds may have some drawbacks. For example, the effectiveness of quaternary ammonium salts (e.g benzalkonium chloride) to disrupt cell membranes and kill lithobionts has been well demonstrated (Wessels and Ingmer 2013; Vannini et al 2018;Sanmartín et al 2020), but their use can promote bacterial adaptation and antibiotic resistance (Kampf 2018;Kim et al 2018;Poursat et al 2019). Moreover, their degradation is suspected to contribute to nitrogen supply (Scheerer et al 2009), thus favouring, rather than preventing, recolonization by aggressive nitrophytic species.…”

Natural Purification Through Soils: Risks and Opportunities of Sewage Effluent Reuse in Sub-surface Irrigation

“…Sorption is typically quantified by an equilibrium organic carbon-water partition coefficient (K oc ), defined as the ratio of the concentration in soil or sediment organic carbon (mg/kg) vs. the concentration in surrounding water (mg/L) at equilibrium (Arp et al 2017). The terms transformation or degradation refer to structural modification of an organic chemical (primary transformation) or its complete breakdown to CO 2 and water (ultimate transformation) (Poursat et al 2019). The degree to which an organic CoEC will react to its environment is dependent on its intrinsic and extrinsic characteristics (Schulze et al 2019).…”

“…Accordingly, significant interest continues to grow in the most efficient, feasible, and environmentally friendly approaches for the transformation of CoECs (Bilal et al 2019). This includes the induction of microbial adaptation (Poursat et al 2019), which will be discussed in the next section.…”

“…(1) microbial interactions within the community and governed by microbial ecology concepts, (2) the genetic information that controls the functional potential of the whole community, and (3) the interplay between the microbial community and the environment. At the level of the individual cell, adaptation can refer either to phenotypic or genetic adaption (Poursat et al 2019). Several studies have described the adaptation of microorganisms to chemical stressors, which they then use as energy sources, i.e., growth-linked transformation, or acquire the ability to co-metabolize (Campa et al 2018;Poursat et al 2019;Wagner et al 2018;Winkler et al 2019).…”

Methane oxidation and methylotroph population dynamics in groundwater mesocosms

“…After transplantation of a natural community into a laboratory environment, adaptation and/or acclimat(izat)ion will occur, and these processes may affect community functions such as methane oxidation (Poursat et al, 2019). This can also lead to turnover and succession of individual populations.…”