Enrichment and Analysis of Stable 1,4-dioxane-Degrading Microbial Consortia Consisting of Novel Dioxane-Degraders

Abstract

Biodegradation of 1,4-dioxane, a water contaminant of emerging concern, has drawn substantial attention over the last two decades. A number of dioxane-degraders have been identified, though many of them are unable to metabolically utilize 1,4-dioxane. Moreover, it is considered more preferable to use microbial consortia rather than the pure strains, especially in conventional bioreactors for industrial wastewater treatment. In the present study, a stable 1,4-dioxane-degrading microbial consortium was enriched, namely 112, from industrial wastewater by nitrate mineral salt medium (NMSM). The consortium 112 is capable of utilizing 1,4-dioxane as a sole carbon and energy source, and can completely degrade 1,4-dioxane up to 100 mg/L. From the consortium 112, two 1,4-dioxane-degrading bacterial strains were isolated and identified, in which the Variovorax sp. TS13 was found to be a novel 1,4-dioxane-degrader that can utilize 100 mg/L of 1,4-dioxane. The efficacy of the consortium 112 was increased significantly when we cultured the consortium with mineral salt medium (MSM). The new consortium, N112, could utilize 1,4-dioxane at a rate of 1.67 mg/L·h. The results of the ribosomal RNA intergenic spacer analysis (RISA) depicted that changes in the microbial community structure of consortium 112 was the reason behind the improved degradation efficiency of consortium N112, which was exhibited as a stable and effective microbial consortium with a high potential for bioremediation of the dioxane-impacted sites and contaminated industrial wastewater.

Isolation and Characterization of Novel Bacteria Capable of Degrading 1,4-Dioxane in the Presence of Diverse Co-Occurring Compounds

“…Isolation and characterization of metabolic 1,4-D-degrader is of utmost importance not only to develop an efficient biological treatment system using pure culture for 1,4-D-contaminated industrial wastewater [ 13 , 16 ] but also to understand their interactions while co-existing in the 1,4-D-degrading microbial consortia known to be more effective and robust as compared to pure culture [ 15 ]. The present study isolated and identified three metabolic 1,4-D-degrading bacteria ( Pseudonocardia sp.…”

“…The metabolic 1,4-D-degrading bacteria was isolated by spreading the microbial inoculum of the consortium N112 on mineral salt medium (MSM, pH 7.0) agar plates supplemented with 100 mg/L of 1,4-D. The composition of MSM used in this study is described in Tusher et al [ 15 ]. After incubating the plates at 30 °C, single colonies of distinct bacterial species were identified and inoculated into 20 mL vials containing 10 mL of sterile MSM supplemented with 100 mg/L of 1,4-D.…”

“…Over the past decades, a plethora of phylogenetically diverse 1,4-D metabolizing and co-metabolizing bacteria have been isolated and identified [ 6 , 13 , 14 , 15 , 16 ]. As a result, biological treatment using 1,4-D-degrading bacteria has been receiving substantial attention as it is cost effective, energy efficient, and environment friendly as compared to advanced oxidation processes (AOPs), the only available chemical treatment technologies for 1,4-D [ 13 , 17 ].…”

“…Thus, identification and characterization of novel 1,4-D-degrading bacteria, especially the Gram-negative degraders, capable of utilizing 1,4-D as a sole carbon and energy source, are important to assess their potential in the application of treatment of 1,4-D-contaminated industrial wastewater containing additional organic load. In our previous study [ 15 ], we enriched a stable 1,4-D-degrading microbial consortium, named N112, from industrial wastewater and assumed that the consortium would consist of novel Gram-negative 1,4-D-degraders coexisting with well-known 1,4-D-degrading Gram-positive bacteria belonging to the genus Pseudonocardia . Thus, this study aimed to isolate, identify, and characterize metabolic 1,4-D-degraders co-existing in the consortium N112 in order to investigate their 1,4-D degradation behaviors; key enzymes initiating 1,4-D degradation; the substrate range; and 1,4-D degradation efficacy in the presence of additional carbon sources, including easy-to-degrade compounds, potential biodegradation intermediates, structural analogs, and other organic co-contaminants.…”

High Throughput Sediment DNA Sequencing Reveals Azo Dye Degrading Bacteria Inhabit Nearshore Sediments

“…A comprehensive characterization of microbial functional diversity is essential for a better understanding of contaminated site bioremediation [19][20][21]. However, most studies on azo dye degradation focused on isolation, identification, and characterization of culturable bacteria [22,23]. It is estimated that only 0.1-1% microorganisms are culturable using conventional methods.…”