Study on community structure of microbial consortium for the degradation of viscose fiber wastewater

Abstract

Background: Enrichment culture was applied to obtain microbial consortium from activated sludge samples collected from biodegradation system, a chemical fiber plant in Hebei Province, China. Bacterial composition and community dynamic variation were assessed employing denaturing gradient gel electrophoresis fingerprinting technology based on amplified 16S rRNA genes in the entire process of enrichment culture for viscose fiber wastewater.

Results: Four bacteria named as VF01, VF02, VF03, and VF04 were isolated from the microbial consortium adopting the spray-plate method. The DNA bands of these four bacteria were corresponded to the predominant DNA bands in the electrophoresis pattern. VF01, VF02, VF03, and VF04 were phylogenetically closed to Bacillus licheniformis, Bacillus subtilis, Paracoccus tibetensis, and Pseudomonas sp. by sequence analysis, respectively. The degradation effects for COD_Cr of single isolated strain, mixed strains, and microbial consortium (VF) originally screened from viscose fiber wastewater were determined. The degradation ability was as follows: microbial consortium (VF) > mixed strains > single isolated strain. Microbial consortium (VF) showed the optimum degradation rate of COD_Cr of 87% on 14th day. Degradation of pollutants sped up by bio-augmentation of four strains. The molecular weight distribution of organic matter showed that viscose fiber wastewater contained a certain amount of large molecular organic matter, which could be decomposed into smaller molecular substances by microbial consortium (VF).

Conclusions: The microbial consortium (VF) obtained from enrichment culture exhibited great potential for COD_Cr degradation. The screened strains had bio-augmentation functions and the addition of a mixture of four bacteria could speed up the degradation rate of pollutants.

Keywords: Bio-augmentation technology; Community structure; DGGE fingerprinting technology; Viscose fiber wastewater.

Fig. 1

DGGE analysis of microbial community structure change under the selective pressure of viscose fiber wastewater (Lanes 1 1st day of subculture; 2 10th day of subculture; 3 20th day of subculture; 4 30th day of subculture; 5 40th day of subculture)

Fig. 2

Analysis using DGGE and comparison of V3 fragments derived from enrichment culture and bacterial isolates (lane VF01–VF04 isolates from the activated sludge; Lane mixed culture mixed culture at 14th day of subculture)

Fig. 3

a Phylogenetic tree with cut bands: Band 1, Band 2, Band 7, Band 10; isolated strains: VF01, VF02, VF03, VF04; and their closest relatives derived from GenBank data based on 16S rRNA gene analysis. b The percentage of “community” in this kind of wastewater

Fig. 4

Biodegradation of COD_Cr by individual isolates, mixture of the four isolates, and the consortium VF

Fig. 5

Biodegradation of COD_Cr by mixture of the four isolates, the consortium VF, and mixture + the consortium VF

Fig. 6

The molecular weight distribution and proportion of DOM in sewage biodegraded by different combinations of microorganisms for different days [mix + VF mixture with the consortium (VF)]