Isolation and characterization of nitroguanidine-degrading microorganisms

Combined sorption-biodegradation for removal of energetic compounds from stormwater runoff

Munition constituents (MC) in stormwater runoff have the potential to move these pollutants into receiving bodies at military installations. Here we present further evaluation of a passive and sustainable biofilter technology for removal of dissolved MC from simulated surface runoff by combined sorption-biodegradation processes under dynamic flow conditions. Columns were packed with MC sorbents Sphagnum peat moss and cationized (CAT) pine shavings with and without wood-based biochar. Some columns also received biodegradable polymers as a slow-release carbon source and MC degrading bacterial cultures. MC removal was greater under combined sorption-biodegradation conditions than under sorption only conditions, ranging from 2.5-fold for 2,4,6-trinitrotoluene (TNT) to > 25-fold for hexahydro-1,3,5-trinitro-s-triazine (RDX). Biochar improved removal for some MC, which was attributed to it acting as a buffer by its ability to sorb/degrade these compounds, thus delaying their elution from the columns until the biodegradation activity increased. It was also found that labile carbon source availability, rather than microbial culture viability, was responsible for the apparent reduction in energetic removal over time. These results provide a foundation for further development of technologies for remediation of energetic compounds in military range stormwater runoff.

Nexus of Soil Microbiomes, Genes, Classes of Carbon Substrates, and Biotransformation of Fluorotelomer-Based Precursors

The unpredictable biodegradation of fluorotelomer (FT)-based per- and polyfluoroalkyl substances (PFAS) causes complicated risk management of PFAS-impacted sites. Here, we have successfully used redundancy analysis to link FT-based precursor biodegradation to key microbes and genes of soil microbiomes shaped by different classes of carbon sources: alcohols (C2-C4), alkanes (C6 and C8), an aromatic compound (phenol), or a hydrocarbon surfactant (cocamidopropyl betaine [CPB]). All the enrichments defluorinated fluorotelomer alcohols (n:2 FtOH; n = 4, 6, 8) effectively and grew on 6:2 fluorotelomer sulfonate (6:2 FtS) as a sulfur source. The butanol-enriched culture showed the highest defluorination extent for FtOHs and 6:2 FtS due to the high microbial diversity and the abundance of desulfonating and defluorinating genes. The CPB-enriched culture accumulated more 5:3 fluorotelomer carboxylic acid, suggesting unique roles of Variovorax and Pseudomonas. Enhanced 6:2 FtOH defluorination was observed due to a synergism between two enrichments with different carbon source classes except for those with phenol- and CPB-enriched cultures. While the 6:2 fluorotelomer sulfonamidoalkyl betaine was not degraded, trace levels of 6:2 fluorotelomer sulfonamidoalkyl amines were detected. The identified species and genes involved in desulfonation, defluorination, and carbon source metabolism are promising biomarkers for assessing precursor degradation at the sites.

Co-occurrence, toxicity, and biotransformation pathways of metformin and its intermediate product guanylurea: Current state and future prospects for enhanced biodegradation strategy

Accumulation of metformin and its biotransformation product "guanylurea" are posing an increasing concern due to their low biodegradability under natural attenuated conditions. Therefore, in this study, we reviewed the unavoidable function of metformin in human body and the route of its release in different water ecosystems. In addition, metformin and its biotransformation product guanylurea in aquatic environments caused certain toxic effects on aquatic organisms which include neurotoxicity, endocrine disruption, production of ROS, and acetylcholinesterase disturbance in aquatic organisms. Moreover, microorganisms are the first to expose and deal with the release of these contaminants, therefore, the mechanisms of biodegradation pathways of metformin and guanylurea under aerobic and anaerobic environments were studied. It has been reported that certain microbes, such as Aminobacter sp. and Pseudomonas putida can carry potential enzymatic pathways to degrade the dead-end product "guanylurea", and hence guanylurea is no longer the dead-end product of metformin. However, these microbes can easily be affected by certain geochemical cycles, therefore, we proposed certain strategies that can be helpful in the enhanced biodegradation of metformin and its biotransformation product guanylurea. A better understanding of the biodegradation potential is imperative to improve the use of these approaches for the sustainable and cost-effective remediation of the emerging contaminants of concern, metformin and guanylurea in the near future.