Heavy metal-resistant bacteria can be efficient bioremediators of metals and might provide an alternative method for metal removal in contaminated environments. The present study aims to isolate bacteria from the aquatic environment and evaluate their potential tolerance to copper metal, aiming at bioremediation processes. Also, compare co-resistance to heavy metal and antibiotics. The morphology of isolates was observed, and sequence analysis (16S ribosomal DNA) revealed that isolated strains were closely related to species belonging to the genera Enterococcus and Bacillus. Bacterial isolates were resistant to CuSO4, with a minimum inhibitory concentration of 0.78 mg ml-1. Enterococcus lactis was resistant to a combination of copper and tetracycline. The other tested isolates were sensitive to the tested antimicrobials. The metal removal ability of these isolates was assayed using atomic absorption spectroscopy, and the strains 27, 23, and E. lactis were best at removing heavy metals, at 87.7%. Enterococcus casseliflavus EC55 was 62%, followed by Bacillus aerius (18.4%), E. casseliflavus EC70 (10%) and Bacillus licheniformis (10%). Based on our findings, Enterococcus sp and Bacillus sp. have potential applications in enhanced remediation of contaminated environments.

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Background Water healthiness is fundamental in medical facilities. Monitoring Legionella spp. and agar cultures concentration is therefore very important. This study looks into these parameters to examine possible criticalities that could need interventions. Methods We collected 399 Legionella and 82 agar cultures withdrawals between November 2019 and February 2020 from 157 detection points (like taps and showers) in 31 structures of four health districts. Withdrawals referred to the 4 quarters of year 2019 (t1, t2, t3, t4). Legionella values were expressed in colony forming units (CFU)/l; agar cultures in CFU/ml. We performed a non-parametric analysis to compare mean values between districts. We used the statistical software package SAS version 9.4 for Windows, setting the significance level at α = 0.05. Results 45% of structures presented at least one positive withdrawal for Legionella (in six we found positivity in more than 1 quarter). Concerning Legionella concentration, we found significant difference between districts in t2 (p = 0.012) and between wards of one district in t3 (p < 0.05). We observed agar positive values in 11 structures (in four cases in more than 1 quarter). In t4 we found a very significant difference (p < 0.0001) between agar values in the four districts, while in t3 we observed a non significant association (p = 0.067). In t3 we found a significant difference for agar values between wards of one district (p = 0.025). We finally considered the simultaneous presence or absence of Legionella and agar positivities: without considering quarters division, we observed accordance (both present or both absent) in 60 detection points, while in 34 points we didn't find it. Conclusions Data provided by this study show that Legionella is rather present in our districts, revealing an association with concentration of CFU in agar. Disinfecting operations should be implemented considering the differences between districts to provide a safe water in every ward. Key messages Water quality monitoring in healthcare facilities is fundamental to provide a safe and healthy environment. Legionella spp. and agar cultures concentrations depend by quarter and spot considered; focused operations should be taken into account to improve disinfection quality.

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