Duygu Nur Arabacı

Background/Objectives: Klebsiella pneumoniae is a clinically important pathogen that causes respiratory tract infections, pneumonia, wound infections, urinary tract infections, and sepsis. It is on the World Health Organization (WHO) priority pathogen list as it causes antimicrobial-resistant infections. The aim of this study was to isolate bacteriophages against pan-resistant K. pneumoniae isolated from clinical wound infections. Results: One of the isolated phages, CTF-1, possesses a linear double-stranded DNA genome that is 40,841 base pairs (bp) long and contains 44 predicted genes. Functional assignments were made for 31 of the predicted gene products, which are associated with genome replication, phage packaging, structural proteins, and host lysis, leaving 13 annotated as hypothetical proteins. Based on sequencing analysis, phage CTF-1 is a new member of the genus Przondovirus within the order Autographivirales. Phage CTF-1 was effective against 22 of 25 (88%) pan-resistant K. pneumoniae isolates. The latent period and lytic cycle of the phage were approximately 40 min, with a burst size of about 92 PFU/mL. Conclusions: Our findings suggest that Klebsiella phage CTF-1 is an excellent candidate for phage therapy due to its high lytic activity against pan-resistant K. pneumoniae strains and lack of genes encoding antibiotic resistance, toxins, virulence factors, or integrases.

A novel lytic bacteriophage, PSA-KC1, was isolated from wastewater. In this study, the whole genome of the bacteriophage PSA-KC1 was analyzed, and its lytic properties were assessed. PSA-KC1 has a linear double-stranded DNA genome with a total length of 43,237 base pairs and a GC content of 53.6%. In total, 65 genes were predicted, 46 of which were assigned functions as structural proteins involved in genome replication, packaging or phage lysis. PSA-KC1 belongs to the genus Septimatrevirus under the Caudoviricetes class. The aim of this study was to investigate the efficacy of the lytic bacteriophage PSA-KC1 and compare it with that of the Pyophage phage cocktail on 25 multi drug resistant (MDR) Pseudomonas aeruginosa strains isolated from sputum samples of cystic fibrosis patients. Seventeen of these strains were susceptible (68%) to the PSA-KC1 lytic phage we isolated, whereas eight clinical strains were resistant. However, 22 (88%) of the P. aeruginosa strains were susceptible to the Pyophage cocktail, and three (12%) were resistant to the Phage cocktail. At the end of our study, a new lytic phage active against multidrug-resistant P. aeruginosa strains from CF patients was isolated, and its genome was characterized. Since the PSA-KC1 phage does not contain virulence factors, toxins or integrase genes, it can be expected to be a therapeutic candidate with the potential to be used safely in phage therapy.

The impact of water hyacinth (Eichhornia crassipes) root biomass (WHRB) on pharmaceutical wastewater treatment with an aerobic hollow-fiber membrane bioreactor (HF-MBR) was investigated. The performance of the bioreactor was assessed in terms of COD (Chemical Oxygen Demand) and antibiotic removal and membrane biofouling rate. For deeper insight, microbial communities in sludge and biofilm layers were analyzed through Illumina sequencing. The addition of WHRB into the HF-MBR increased the COD (by 6%), as well as antibiotics and transformation products removal efficiency. Removal efficiencies of 97%, 98% and 84% were obtained for removal of erythromycin, sulfamethoxazole, and tetracycline. Furthermore, WHRB modified the biodegradation network, increased the relative abundances of Chloroflexi, Proteobacteria and Nitrospirae and decreased Firmicutes, compared with the control with antibiotics. The addition of WHRB also enriched Actinobacteria and Bacteroidetes while decreasing the phylla Chloroflexi and Saccharibacteria in the biofilm.

Membrane bioreactors are powerful systems for wastewater treatment and the removal of toxic compounds. However, membrane biofouling stands in the way of their widespread usage. In this study, the saprophytic fungus Trichocladium canadense was used as the bioaugmentor in an anaerobic membrane bioreactor (AnMBR) and its impact on membrane biofouling, biogas production, the microbial communities of the reactor and removal of the common antibiotics erythromycin (ERY), sulfamethoxazole (SMX) and tetracycline (TET) from synthetic wastewater was investigated. The results indicated that through bioaugmentation with 20% T. canadense, membrane biofouling was slowed by 25%, the chemical oxygen demand removal increased by 16% and a higher efficiency removal of ERY and SMX was achieved. The presence of T. canadense significantly increased the abundance and diversity of the biofilm archaeal community and the bacterial phylum Firmicutes, a known bio-foulant. Graphical Abstract

To address the inadequate removal of antibiotic resistance genes in wastewater treatment plants, this study investigated the impact of bioaugmentation with dried Eichhornia crassipes roots on removal of antibiotics sulfamethoxazole, tetracycline and erythromycin from pharmaceutical wastewater while optimizing potential for reclaiming value through biogas production, utilizing an anaerobic membrane bioreactor (AnMBR). Three sets of AnMBRs were set up for the experiment, C1 (inoculum), C2 (inoculum + antibiotics) and EC (inoculum + antibiotics + E. crassipes). The results showed that E. crassipes mitigated some of the toxic effects of antibiotics on the microbial community and prevented negative impact on the archaeal community, and significantly increased average biogas production (by 37% compared to control without antibiotics and 42% compared to control with antibiotics) as well as antibiotics removal. Furthermore, bioaugmented reactor showed significant reduction of erythromycin (97%) and tetracycline (83%) concentrations in effluent. Utilization of E. crassipes root offers a simple yet powerful tool for preventing the emergence of antimicrobial resistance and dissemination of such pollutants into the environment. GRAPHICAL ABSTRACT