Dataset Information

Molecular Identification and Characterization of Bacillus sp. NIGAB-1 for Phenol Degradation Under Saline Conditions.

ABSTRACT: Background:Phenol is an aromatic pollutant in industrial wastes that in combination with salts is highly toxic for all forms of life. Phenol elimination is the foremost challenge to meet the goal of pollutant-free environment. Objective:The present study was carried out to isolate phenol degrading bacteria which can degrade phenol under saline conditions and to identify the isolated strains using 16S rRNA gene sequence analysis. Material and Methods:Sediment samples were collected from Rawal Lake, Islamabad, Pakistan and enriched in mineral salt medium (MSM) containing phenol (150 mg.L-1). Isolated strains were identified on the basis of 16S rRNA gene sequence analysis. Growth of strains were tested at different pH, NaCl concentrations and temperature using Tryptic Soy Agar (TSA). Tolerance to phenol (0-750 mg.L-1) was checked at 5% NaCl and phenol degrading experiment was performed at 4% NaCl, pH 7 and 30 oC. In both, phenol tolerance and degradation study, phenol was used a sole source of carbon and energy. Results:Thirteen bacterial strains were isolated after enrichment among which, NIGAB-1 was found capable of degrading phenol in saline conditions. This strain was identified as Bacillus sp. NIGAB-1 on the basis of 16S rRNA gene sequence analysis and the closest match was Bacillus marisflavi with 99.71% sequence identity. The Bacillus sp. NIGAB-1 exhibited best growth at 30 oC at pH 7 with 10% NaCl. The optimum phenol concentration for growth was recorded as 300 mg.L-1. This strain degraded 300 mg.L-1 of phenol at 4% NaCl in 120 hours with the average degradation rate of 2.63 mg.L-1.h. Conclusion:These findings suggest that this strain could be efficient in phenol degradation at adverse environmental conditions and helpful in remediation of phenol where the salt concentration is high.

SUBMITTER: Ahmad N

PROVIDER: S-EPMC7461705 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Molecular Identification and Characterization of <i>Bacillus</i> sp. NIGAB-1 for Phenol Degradation Under Saline Conditions.

Ahmad Nazir N Ali Ghulam Muhammad GM Khan Muhammad Ramzan MR

Iranian journal of biotechnology 20200101 1

<h4>Background</h4>Phenol is an aromatic pollutant in industrial wastes that in combination with salts is highly toxic for all forms of life. Phenol elimination is the foremost challenge to meet the goal of pollutant-free environment.<h4>Objective</h4>The present study was carried out to isolate phenol degrading bacteria which can degrade phenol under saline conditions and to identify the isolated strains using 16S rRNA gene sequence analysis.<h4>Material and methods</h4>Sediment samples were co ...[more]

PMID: 32884957

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Project description:Closing water loops in chemical industries result in hot and highly saline residual streams, often characterized by high strength and the presence of refractory or toxic compounds. These streams are attractive for anaerobic technologies, provided the chemical compounds are biodegradable. However, under such harsh conditions, effective biomass immobilization is difficult, limiting the use of the commonly applied sludge bed reactors. In this study, we assessed the long-term phenol conversion capacity of a lab-scale anaerobic membrane bioreactor (AnMBR) operated at 55°C, and high salinity (18 gNa+.L-1). Over 388 days, bioreactor performance and microbial community dynamics were monitored using specific methanogenic activity (SMA) assays, phenol conversion rate assays, volatile fatty acids permeate characterization and Illumina MiSeq analysis of 16S rRNA gene sequences. Phenol accumulation to concentrations exceeding 600 mgPh.L-1 in the reactor significantly reduced methanogenesis at different phases of operation, while applying a phenol volumetric loading rate of 0.12 gPh.L-1.d-1. Stable AnMBR reactor performance could be attained by applying a sludge phenol loading rate of about 20 mgPh.gVSS-1.d-1. In situ maximum phenol conversion rates of 21.3 mgPh.gVSS-1 .d-1 were achieved, whereas conversion rates of 32.8 mgPh.gVSS-1 .d-1 were assessed in ex situ batch tests at the end of the operation. The absence of caproate as intermediate inferred that the phenol conversion pathway likely occurred via carboxylation to benzoate. Strikingly, the hydrogenotrophic SMA of 0.34 gCOD-CH4 .gVSS-1 .d-1 of the AnMBR biomass significantly exceeded the acetotrophic SMA, which only reached 0.15 gCOD-CH4 .gVSS-1 .d-1. Our results indicated that during the course of the experiment, acetate conversion gradually changed from acetoclastic methanogenesis to acetate oxidation coupled to hydrogenotrophic methanogenesis. Correspondingly, hydrogenotrophic methanogens of the class Methanomicrobia, together with Synergistia, Thermotogae, and Clostridia classes, dominated the microbial community and were enriched during the three phases of operation, while the aceticlastic Methanosaeta species remarkably decreased. Our findings clearly showed that highly saline phenolic wastewaters could be satisfactorily treated in a thermophilic AnMBR and that the specific phenol conversion capacity was limiting the treatment process. The possibility of efficient chemical wastewater treatment under the challenging studied conditions would represent a major breakthrough for the widespread application of AnMBR technology.

Dataset Information

Molecular Identification and Characterization of Bacillus sp. NIGAB-1 for Phenol Degradation Under Saline Conditions.

Publications

Molecular Identification and Characterization of <i>Bacillus</i> sp. NIGAB-1 for Phenol Degradation Under Saline Conditions.

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