Effects of entrapment on nucleic acid content, cell morphology, cell surface property, and stress of pure cultures commonly found in biological wastewater treatment

Abstract

The effects of cell entrapment on nucleic acid content, cell morphology, cell surface property, and stress of major groups of bacteria (betaproteobacteria and gammaproteobacteria) in biological municipal wastewater treatment were investigated. Three different entrapment media (alginate, carrageenan, and polyvinyl alcohol) were examined. Results indicated that the entrapment and type of entrapment media affected nucleic acid content, cell morphology, cell surface property, and stress of the three representative species (Alcaligenes faecalis, Comamonas testosteroni, and Pseudomonas putida) studied. The highest deoxyribonucleic acid and ribonucleic acid increases were observed with the alginate and polyvinyl alcohol (PVA) entrapment, respectively. A cell morphological change from bacilli to coccoidal was observed in the case of alginate entrapment while the PVA-entrapped cells had a slim morphology when compared to non-entrapped cells and formed putative nanowires. The entrapment increased or decreased the surface roughness of cells depending on the type of entrapment media. Expression of a nitrosative stress gene, which is linked to oxygen deprivation, was observed more in the alginate-entrapped cells. These research findings advance the fundamental understanding of the entrapped cell physiology which can lead to more efficient entrapped cell-based wastewater treatment.

Nanoscale zero-valent iron for metal/metalloid removal from model hydraulic fracturing wastewater

“…The scanning degrees were from 5° to 70° 2θ with 5° min -1 speed duration at 45 kV and 200 mA. For XPS analysis, the entrapped nZVI was released by dissolving beads in 0.3 M sodium citrate solution and 20 mM phosphate buffer solution according to a previous study (Pramanik et al, 2011), as otherwise dense polymeric matrix outside nZVI interfered the surface analysis. The solid samples were freeze-dried and kept in a desiccator before analysis.…”

Aging effects on chemical transformation and metal(loid) removal by entrapped nanoscale zero-valent iron for hydraulic fracturing wastewater treatment

“…After reaction with Cu(II)/Zn(II)/Cr(VI)/As(V) in Day-90 FWW, PVA-alginate entrapped beads were separated by centrifugation and gently washed with DIW three times to remove entrapped and loosely attached metals and salts. For X-ray photoelectron spectroscopy (XPS) analysis, the entrapped nZVI was released by dissolving the beads in 0.3 M sodium citrate solution and 20 mM phosphate buffer solution according to a 9 previous study (Pramanik et al, 2011) (otherwise dense polymeric matrix enclosing nZVI interfered with the surface analysis). The solid samples were freeze-dried and kept in a desiccator before analysis.…”