MICROFLORA OF 2,4-DICHLOROPHENOXYACETIC ACID DEGRADING BIOFILMS ON GAS-PERMEABLE MEMBRANES

Citation
C. Rothemund et al., MICROFLORA OF 2,4-DICHLOROPHENOXYACETIC ACID DEGRADING BIOFILMS ON GAS-PERMEABLE MEMBRANES, Systematic and applied microbiology, 19(4), 1996, pp. 608-615
Citations number
51
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology,"Biothechnology & Applied Migrobiology
ISSN journal
0723-2020
Volume
19
Issue
4
Year of publication
1996
Pages
608 - 615
Database
ISI
SICI code
0723-2020(1996)19:4<608:MO2ADB>2.0.ZU;2-N
Abstract
Bacteria with specific metabolic capabilities are required for the deg radation of industrial wastewater. In reactors with suspended biomass these organisms may easily be washed out. Reactors with immobilized bi omass appear to be better suited to retain those organisms in the syst em. In order to monitor immobilization efficiency of such a biofilm re actor; the composition of the biofilm grown in the reactor has to be e xamined. In this study a Membrane Biofilm Reactor (MBR) was inoculated with Alcaligenes eutrophus JMP 134 to yield 2,4-dichlorophenoxyacetic acid (2,4-D) degrading biofilms. In a MBR the biofilm is supplied wit h oxygen through a membrane from the gas compartment and with substrat e from the bulk liquid. In situ hybridization of cross sections of the biofilm with 16S rRNA-targeted oligonucleotide probes revealed the sp atial distribution of bacterial cells in the biofilm. hn oligonucleoti de probe specific for the 2,4-degrading strain A. eutrophus JMP 134 wa s developed based on comparative sequence analysis. A. eutrophus JMP 1 34 cells were hardly found directly attached to the membrane, but clus ters of them colonized e. g. the testaceous amoebae in the laver close to the membrane. The biofilm itself consisted of three different laye rs. The bottom layer was characterized by clusters of testaceous amoeb ae covered with bacterial cells from all groups examined. The base bio film layer contained organisms of the beta-subclass and - in most case s - fungi. The surface layer exhibited again a higher diversity of bac terial cells and some testaceous amoebae. The overall composition of t he biofilm was characterized by a dominance of organisms of the beta-s ubclass of Proteobacteria. Cells of A. eutrophus JMP 134 were found in all three layers, but in different morphological shapes.