The effects of emerging environmental contaminants on Stenotrophomonas maltophilia isolated from drinking water in planktonic and sessile states

Abstract

Concerns on the presence of emerging contaminants (ECs) in water sources have increased in recent years. The lack of efficient technologies to remove ECs from residual waters contributes for their appearance in drinking water distribution systems (DWDS). Therefore, sessile microorganisms on DWDS pipes are continuously exposed to trace concentrations of ECs. However, no data exists on the role of ECs on the resident microbiota. The present work aims to understand the effects of prolonged exposure of a bacterial strain of Stenotrophomonas maltophilia, isolated from a DWDS, in both planktonic and biofilm states, to trace concentrations of selected ECs (antipyrine-ANTP; diclofenac sodium salt-DCF; ibuprofen-IBP; galaxolide-GAL; tonalide-TON; carbamazepine-CBZ; clofibric acid-CA; tylosin-TY) on its tolerance to sodium hypochlorite (NaOCl) and resistance to antibiotics. Pre-established S. maltophilia biofilms were exposed to ECs for 26 d. Subsequently, the planktonic behaviour of the biofilm cells grown in the presence of ECS was characterized in terms of susceptibility to NaOCl and to selected antibiotics (levofloxacin and trimethoprim-sulfamethoxazole). Moreover, S.maltophilia was tested on its biofilm productivity in the presence of ECs (alone and mixed). These biofilms were challenged by NaOCl in order to assess the role of ECs on biofilm susceptibility. The results did not evidence remarkable effects of ECs on planktonic S. maltophilia susceptibility to NaOCl and antibiotics. However, S. maltophilia biofilm production and susceptibility to NaOCl was affected from ECs pre-exposure, particularly by the combination of different ECs (CA + CBZ, CA + IBP, CA + CBZ + IBP). S. maltophilia biofilms became more resistant to removal by NaOCl when developed in the presence of mixtures of CA + CBZ and CA + CBZ + IBP. Also, biofilm production was significantly affected. CA was present in all the combinations that altered biofilm behaviour. The overall results propose that exposure to ECs for 26 days had not a huge impact on S. maltophilia planktonic antimicrobial susceptibility. Nevertheless, the prolonged exposure to some ECs altered biofilm production and tolerance to NaOCl, with a potential practical outcome of hindering DWDS disinfection. The simultaneous presence of different ECs in the environment may amplify biofilm resilience.

Removal of Enteric Pathogens from Real Wastewater Using Single and Catalytic Ozonation

“…The conventional wastewater treatment reveals difficulty in removing both chemical and biological emerging contaminants from water [1][2][3][4][5][6][7]. Among these pollutants, pharmaceutical and personal care products, as well as enteric pathogens [8][9][10][11][12], are of concern.…”

Adhesion of filamentous fungi isolated from drinking water under different process conditions

“…The final suspension of spores was homogenized and quantified using a Neubauer count chamber. Several aliquots of suspensions of spores with 10% of glycerol (HiMedia, India) were cryopreserved at À80 C. Stock suspensions were resuspended in a volume of R2A broth or STW [media composition previously described by Gomes et al (2018)] necessary to achieve a density of 10 5 spores/mL for adhesion assays.…”

The role of surface copper content on biofilm formation by drinking water bacteria

“…Acinetobacter calcoaceticus and Stenotrophomonas maltophilia, previously isolated from DW, 31 were grown overnight at 25 C and under agitation (120 rpm) in R2A broth medium according to Gomes et al 32 Aerwards, bacterial cells were harvested by centrifugation (Eppendorf centrifuge 5810R) at 3777 Â g, 15 min, and resuspended in synthetic tap water (STW) composed by 100 mg L À1 NaHCO 3 (Fisher Scientic, Leicestershire, UK), 13 mg L À1 MgSO 4 $7H 2 O (Merck, Darmstadt, Germany), 0.7 mg L À1 K 2 HPO 4 (Applichem Panreac, Darmstadt, Germany), 0.3 mg L À1 KH 2 PO 4 (CHEM-LAB, Zedelgem, Belgium), 0.01 mg L À1 (NH 4 ) 2 SO 4 (Labkem, Barcelona, Spain), 0.01 mg L À1 NaCl (Merck, Darmstadt, Germany), 0.001 mg L À1 FeSO 4 $7H 2 O (VWR PROLABO, Leuven, Belgium), 1 mg L À1 NaNO 3 (Labkem, Barcelona, Spain), 27 mg L À1 CaSO 4 (Labkem, Barcelona, Spain), 1 mg L À1 humic acids (Sigma-Aldrich, Steinheim, Germany). 33,34 The cell density was adjusted to 1 Â 10 6 CFU per mL for further experiments.…”

“…Each coupon was inserted in a 50 mL centrifuge tube containing 3.5 mL of saline water (8.5 g L À1 of NaCl) aer being scrapped with a micropipette tip while 1 mL of saline water was dispensed on the coupon to help the removal of the scrapped cells. 32 Then, 0.5 mL of thiosulphate (0.5% w/v) was added to the tube containing the scrapped suspension in order to neutralize the effects from the copper ions released. 36 Tubes containing coupons were then vortexed for 2 min to complete the removal of adhered bacteria and to dissociate possible bacterial aggregates.…”

“…36 Tubes containing coupons were then vortexed for 2 min to complete the removal of adhered bacteria and to dissociate possible bacterial aggregates. 32 Serial dilutions from the obtained suspension were then performed and plated on R2A agar (Oxoid, Hampshire, UK) plates. Colony forming units (CFU) were enumerated aer incubation for 48 h at 25 C. For dual species biolms, the number of CFU per cm 2 was also assessed for each bacterium.…”