Atrazine biodegradation by a bacterial community immobilized in two types of packed-bed biofilm reactors

Abstract

Through selective enrichment of atrazinemetabolizing microorganisms, a microbial community was selected from agricultural soil. Bacterial isolates, identified by their closest similarity with 16S rDNA sequences stored in NCBI GeneBank, belonged to the genera: Massilia, Stenotrophomonas, Klebsiella, Sphingomonas, Ochrobactrum, Arthrobacter, Microbacterium, Xanthomonas and Ornithinimicrobium. From these strains, only the first six used atrazine as nitrogen and carbon source. The microbial community attached to a non-porous support was evaluated for its atrazine biodegradation rate and removal efficiency under aerobic conditions in two types of packed-bed biofilm reactors fed with a mineral salt medium containing glucose plus atrazine, or atrazine as the sole carbon and nitrogen source. Removal efficiencies near 100% were obtained at loading rates up to 10 mg l -1 h -1 . After long periods of continuous operation, the richness of microbial species in biofilm reactors diminished to only three bacterial strains; Stenotrophomonas sp., Ochrobactrum sp. and Arthrobacter sp. By PCR analysis of their DNA, the presence of atzABC genes codifying for the enzymes of the upper catabolic pathway of atrazine, was confirmed in the three strains. The gene atzD that encodes for the cyanuric acid amidohydrolase enzyme was detected only in Stenotrophomonas sp.

Simultaneous degradation of atrazine and simazine by a binary culture of Stenotrophomonas maltophilia and Arthrobacter sp. in a two‐stage biofilm reactor

“…34 Thus, the organization of atrazine-catabolic genes seems highly variable among Arthrobacter strains, suggesting that transposition may contribute to disperse the genes coding for enzymes of the atrazine-degradation pathway. 35 In the case of the Arthrobacter strain used in this work, the genes atzA, atzB and atzC have been previously identified, 18 and their presence was corroborated by PCR amplification of Arthrobacter DNA (Fig. 2(A)), using the primers shown in Table 1.…”

“…(NCBI accession number EU427 314, 84% similarity) are bacterial strains isolated from a microbial consortium able to degrade atrazine. 18 …”

Molecular analysis of atrazine-degrading bacteria and catabolic genes in the water column and sediment of a created wetland in an agricultural/urban watershed

“…Atrazine biodegradation by Sphingomonas spp. has been reported in multiple studies (e.g., Smith and Crowley, 2005;Macías-Flores et al, 2009;Sene et al, 2010). A Methyloversatilis isolate has been previously characterized that can degrade s-triazines (Iwasaki et al, 2007;Takagi et al, 2012).…”

Removal of atrazine from aqueous environment using immobilized Pichia kudriavzevii Atz-EN-01 by two different methods

“…Complete removal of propanil was observed at loading rate of 24.9 mg L À1 h À1 , where the removal efficiency decayed at higher loading rates. Macías-Flores et al (2009) evaluated the atrazine removal efficiency of a microbial community attached to a nonporous support in two types of packed bed biofilm reactors. Removal efficiencies of nearly 100% were obtained at loading rates up to 10 mg L À1 h À1 .…”