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Formation of electrogenic microbial biofilm on the electrode is critical for harvesting electrical power from wastewater in microbial biofuel cells (MFCs). Although the knowledge of bacterial community structures in the biofilm is vital for the rational design of MFC electrodes, an in-depth study on the subject is still awaiting. Herein, we attempt to address this issue by creating electrogenic biofilm on modified graphite anodes assembled in an air–cathode MFC. The modification was performed with reduced graphene oxide (rGO), polyaniline (PANI), and carbon nanotube (CNTs) separately. To accelerate the growth of the biofilm, soybean-potato composite (plant) powder was blended with these conductive materials during the fabrication of the anodes. The MFC fabricated with PANI-based anode delivered the current density of 324.2 mA cm−2, followed by CNTs (248.75 mA cm−2), rGO (193 mA cm−2), and blank (without coating) (151 mA cm−2) graphite electrodes. Likewise, the PANI-based anode supported a robust biofilm growth containing maximum bacterial cell densities with diverse shapes and sizes of the cells and broad metabolic functionality. The alpha diversity of the biofilm developed over the anode coated with PANI was the loftiest operational taxonomic unit (2058 OUT) and Shannon index (7.56), as disclosed from the high-throughput 16S rRNA sequence analysis. Further, within these taxonomic units, exoelectrogenic phyla comprising Proteobacteria, Firmicutes, and Bacteroidetes were maximum with their corresponding level (%) 45.5, 36.2, and 9.8. The relative abundance of Gammaproteobacteria, Clostridia, and Bacilli at the class level, while Pseudomonas, Clostridium, Enterococcus, and Bifidobacterium at the genus level were comparatively higher in the PANI-based anode. [ABSTRACT FROM AUTHOR]

Nanotechnology recently provided useful insight into using a new antibacterial agent with synergistic effects of the bactericide mechanism toward some pathogenic microorganisms. For example, nanosilver and nano zinc oxide represent a class of essential substances that might be widely used in advanced research and healthrelated activities. In the present work, we prepared silver (AgNPs), zinc oxide (ZnONPs) nanoparticles, characterized their structures with "UV-Vis "Spectroscopy, X-ray diffraction (XRD) and High-Resolution Transmission Electron Microscopy (HR-TEM). We then evaluated their antibacterial activity by using different antibiotic discs against Aeromonas hydrophila and Pseudomonas aeruginosa (Gram-negative bacteria), and Staphylococcus aureus (Gram-positive bacteria) isolated from water and fish of Qarun and Manzala Lakes. Also, the minimal inhibitory concentration (MIC) was calculated by the macro dilution method". The obtained results found that AgNPs inhibited the growth of both Gram-positive and Gram-negative bacterial isolates at a concentration of 170 μg/ml. However, ZnONPs inhibited the growth of at 500 μg/ml. Preliminary growth analysis results suggest that silver and zinc oxide nanoparticles have an inhibitory activity on Gram-positive and Gram-negative bacterial isolates. The present study exhibited synthesized (metal, metal oxide) nanoparticles. For potent antibacterial activity, the nanoparticles concentration was considered as a significant factor. Moreover, in low concentrations, Silver nanoparticles inhibited the growth of bacterial strains than zinc oxide nanoparticles. It can be concluded that the application of silver and zinc oxide nanoparticles as antibacterial agents is a promising tool for disease treatment in the field of fish aquaculture. [ABSTRACT FROM AUTHOR]

Since knowledge and understanding of waterborne pathogens and their diseases are well illuminated, a few research publications on the prevalence of pathogenic microorganisms in various household sink drain pipes are often not extensively examined. Therefore, this study aims to (a) assess and monitor the densities of the bacterial community in the different natural biofilm that grow on plastic pipelines, (b) to detect Escherichia coli, Salmonella, and Listeria spp. from natural biofilm samples that are collected from the kitchen (n = 30), bathroom (n = 10), laboratories (n = 13), and hospital (n = 8) sink drainage pipes. Three bacterial species selected were assessed using a culture‐dependent approach followed by verification of isolates using both BIOLOG GEN III and polymerase chain reaction. The estimated number of each bacterium was 122 isolates, while 60, 20, 26, and 16 isolates were obtained from the natural biofilm samples, kitchen, bathroom, laboratories, and hospital, respectively. As for the tests, in all types of biofilm samples, the overall bacterial counts at low temperature (22°C) were higher than those at high temperature (37°C). Meanwhile, E. coli had the most significant number of bacterial microorganisms compared to the other two pathogens. Additionally, the most massive cell densities of E. coli, Salmonella, and Listeria species were discovered in the biofilm collected from the kitchen, then the hospital. Statistically, the results reveal that there is a positive correlation (p ≥.0001) with significance between the sources of biofilm. This work certainly makes the potential of household sink drain pipes for reservoir contagious pathogens more explicitly noticeable. Such knowledge would also be beneficial for prospective consideration of the threat to human public health and the environment. [ABSTRACT FROM AUTHOR]

The cytotoxicity and antimicrobial activity of different Moringa oleifera seeds extracts were tested against Scenedesmus obliquus (green algae). Escherichia coli ATCC 13706. Pseudomonas aeruginosa ATCC10145, Staphlococcus aureus NAMRU 3 25923, Bacillus sterothermophilus (bacterial strains) and Herpes Simplex virus type 1 (HSV 1) and Polio virus type 1 (sabin vaccine). Fixed oil extracted from the seeds was found to activate the growth of Scenedesmus obliquus with high algal biomass production. Aqueous methanolic extracts (LC50 207.5 mg/L) and water extract (LC50 287.5 mg/L) has a cytotoxicity effect on Scenedesmus growth. On the other hand, the antibacterial effects of fixed oil, aqueous methanolic extract and water extract concentrations showed a fluctuation in its effects. Although. Ps. aerugnosa was more resistant to all M. oleifera extracts, B. sterothermophilus was more sensitive than other organisms to all extracts. The effect of aqueous methanolic extract and fixed oil on HSV 1 was highly similar, 52.22% and 45.2%. Very low activity was observed for fixed oil on PV1. [ABSTRACT FROM AUTHOR]

The aim of the study is to estimate the effectiveness of three antibiofilm agents against Escherichia coli biofilm that formed in six different types of pipelines. A laboratory-scale water system was built for this work to allow for the creation of biofilm in the pipelines studied. The level of the growth rate of E. coli biofilm cells was monitored over 90 days on those tested pipe materials. The results of bacterial cell densities displayed that the highest biofilm growth was observed in the biofilm formed on the iron (Fe) pipe. In contrast, the biofilm formation rate was significantly lower on copper (Cu) pipe compared to other materials. Three antibiofilm agents, including chlorine, silver ions (Ag + ), and silver nanoparticles (AgNPs), were employed to eradicate the biofilm cells. E. coli counts indicated that AgNPs are more efficient in destructing any formed biofilm cells on all tested materials. At the same time, the chlorine was only useful in the case of biofilm developed on plastic and Cu. However, the antibiofilm efficiency of Ag + performs similarly to chlorine against E. coli biofilm cells. Ultimately, AgNPs are considred the most powerful antibiofilm agent among the other agents toward the biofilm cells in their maturation stage, which offers an encouraging way for the long-term functioning of water systems. PRACTITIONER POINTS: The growth rate of E. coli biofilm cells was investigated on different materials. The count of biofilm cells developed on iron pipes was higher than other materials. The E. coli biofilm on iron pipe could resist chlorine and AgNPs to a large extent. The developed biofilm on copper pipe was more sensitive to chlorine, Ag + . and AgNPs. The biofilm cells could be easily eradicated from plastic-based materials with all tested disinfectants., (© 2020 Water Environment Federation.)