Effects of cell entrapment on growth rate and metabolic activity of pure cultures commonly found in biological wastewater treatment

Pramanik, Sudipta; Khan, Eakalak

doi:10.1016/j.bej.2009.06.001

Cited by 14 publications

(4 citation statements)

References 36 publications

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“…This observation was also reported in the previous study [185]. In addition, difference in AO rates may be due to quantity and activity survived bacteria after entrapment processes [141]. A former study reported that the percent of live cells in the entrapment (39-62%) was less than those in the corresponding suspended culture (54-74%) before the entrapment was made [186].…”

Section: Microscopic Observation Of Internal Structures Of the Entrap...supporting

confidence: 80%

“…In environmental aspect, PVA is not harmful to activated sludge microorganisms [15,141] and it can be abundantly produced at a low cost [137].…”

Section: Cell Entrapment Using Polyvinyl Alcoholmentioning

confidence: 99%

“…From the remaining activity of AO, it was clearly showed that PVA-entrapped cells could mitigate toxicity impact resulted from AgNPs and Ag + . Previous studies reported that PVA was commonly used for entrapment technique because it is not harmful to activated sludge microorganisms [141,182] and it can be produced massively at a low cost [137]. In the prior study, PVA at 10% (w/v) was applied to entrap microbes to degrade atrazine [17] from agricultural soil.…”

Section: Influence Of Agnps and Ag + On Ao In Pva-entrapped Cellsmentioning

confidence: 99%

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Ammonia oxidation process of entrapped and suspended cell inhibited by silver nanoparticles

Giao

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Silver nanoparticles (AgNPs) are widely used in commercial products because of their excellent antimicrobial activity. Entrance of AgNPs and its released Ag ions (Ag+) into wastewater treatment plants could harm ammonia oxidation (AO) process resulting in environmental problems. This study aimed to study inhibitory effect of AgNPs and Ag+ on AO process in suspended cells of ammonia oxidizing cultures enriched at initial ammonia concentrations of 0.5 and 30 mM (called NAS 0.5 mM and NAS 30 mM, respectively) and then mitigation measures using entrapment technique were tested. The results indicated that AgNPs and Ag+ were higher toxic to NAS 0.5 mM than NAS 30 mM due to different proportion of active ammonia oxidizers and communities. Silver nanoparticles of 1-100 mg/L inhibited AO activity by 90.6 ± 8.6% to 94.8 ± 4.3% and 44.9 ± 2.4% to 73.8 ± 1.5%, whereas Ag+ concentration of 0.05- 0.50 mg/L inhibited by 86.3 ± 0.8% to 93.4 ± 1.24% and 52.7 ± 2.14% to 93.9 ± 1.89% for NAS 0.5 mM and NAS 30 mM, respectively. The inhibition result suggested that the AgNP toxicity mainly derived from the liberated Ag+. The primary mechanism for toxicity of AgNPs and Ag+ caused microbial cell death. Cell entrapped in barium alginate (BA), polyvinyl alcohol (PVA), and the mixture of PVA-BA used to mitigate negative influence of AgNPs and Ag+. The results showed that BA, PVA, and PVA-BA- entrapped cells remained AO 81-100%, 57-97%, and 75-100% at AgNPs 1-100 mg/L whereas the entrapped cells remained AO 98-100%, 61-99%, and 79-100% under Ag+ 0.05-0.50 mg/L, respectively. Less damage of membrane integrity in the entrapped cells experiments with AgNPs and Ag+ indicated that the entrapped cells were less exposed to silver since the entrapment matrices could limit mass transfer of silver into the gel beads. BA and PVA-BA were highly recommended for further study in the mitigating toxicity of AgNPs and Ag+ since they remained high cell viability and more stable in synthetic wastewater.

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Section: Microscopic Observation Of Internal Structures Of the Entrap...supporting

confidence: 80%

“…In environmental aspect, PVA is not harmful to activated sludge microorganisms [15,141] and it can be abundantly produced at a low cost [137].…”

Section: Cell Entrapment Using Polyvinyl Alcoholmentioning

confidence: 99%

Section: Influence Of Agnps and Ag + On Ao In Pva-entrapped Cellsmentioning

confidence: 99%

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Ammonia oxidation process of entrapped and suspended cell inhibited by silver nanoparticles

Giao

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“…Alginate beads were immersed in a 0.3 M sodium citrate solution at pH 5.0 with shaking until complete dissolution was achieved (Roukas, 1996). PVA beads were dissolved at 65-70C in DI water with continuous shaking for 10 min (Pramanik and Khan, 2009). The obtained solutions, which 8 contained the cells, were centrifuged at 14,000 × g for 10 min and pellets were used in the LIVE/DEAD assay.…”

Section: Live/dead Baclight Assaymentioning

confidence: 99%

Mitigation of bactericidal effect of carbon nanotubes by cell entrapment

McEvoy

Khan

2016

Science of The Total Environment

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This study investigated the effects of the alginate and polyvinyl alcohol (PVA) entrapment on the viability of Escherichia coli cells exposed to single wall carbon nanotubes (SWCNTs) with a diameter of 1-2nm. Viability was examined using a galactosidase enzyme assay, LIVE/DEAD BacLight assay, and total ribonucleic acid quantity. Variables studied included SWCNT concentration (5, 10, 20, 50, 100, 200, 500, and 1000μg/ml), SWCNT length (0.5-2μm for short SWCNTs and 5-30μm for long SWCNTs), and initial bacterial concentration (6.5 log10 CFU and 9 log10 CFU per test). Results showed that both alginate and PVA entrapments mitigate the bactericidal effect of SWCNTs. At the highest SWCNT concentration tested (1000μg/ml), the viability of the cells relative to controls (systems with only E. coli, no SWCNTs), was 0-60% for free cells and 60-90% for alginate and PVA entrapped cells. The bactericidal effect depended on SWCNT type and concentration, and bacterial concentration. In general, long SWCNTs (5-30μm) caused significantly greater reductions in the viability of entrapped cells than the short SWCNTs except for the two highest SWCNT concentrations studied, 500 and 1000μg/ml. Microscopy showed that the entrapment matrices prevented SWCNTs from entering the beads. This study shows that bacterial entrapment is effective at limiting the bactericidal effect of SWCNTs.

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

Pramanik

Khanna

Katti

et al. 2011

Appl Microbiol Biotechnol

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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.

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Effects of cell entrapment on growth rate and metabolic activity of pure cultures commonly found in biological wastewater treatment

Cited by 14 publications

References 36 publications

Ammonia oxidation process of entrapped and suspended cell inhibited by silver nanoparticles

Ammonia oxidation process of entrapped and suspended cell inhibited by silver nanoparticles

Mitigation of bactericidal effect of carbon nanotubes by cell entrapment

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

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