|1370-1||New insights in the Microbial Ecology of waste gas and wastewater treatment processes through functional gene targeting: a synthesis of inter laboratory studies|
|Autores:||Léa Cabrol (PUCV - Pontificia Universidad Católica de Valparaíso / EMA - Ecole des Mines d'Ales) ; Luc Malhautier (EMA - Ecole des Mines d'Ales) ; Franck Poly (LEM - Laboratoire d'Ecologie Microbienne, Université Lyon I) ; Germán Aroca (PUCV - Pontificia Universidad Católica de Valparaíso) ; Rolando Chamy (PUCV - Pontificia Universidad Católica de Valparaíso) |
Microbiological-driven processes for the purification of contaminated streams have proved to out-compete conventional chemical processes thanks to high efficiency, low operating costs and limited environmental impact. However, despite their fundamental role, little is known about the structure and function of microbial communities involved in such bioprocesses, leading to empirical and suboptimal operation. The development of molecular techniques enabled culture-independent studies, which evidenced that the microbial community structure is influenced by the operating conditions, and that it can in turn influence the process functional performance. Thereby, a better understanding of the complex relations between relevant macroscopic parameters and the microbial community density, diversity and activity, does not only provide basic knowledge, but also control tools to improve bioprocess operation.
We intend to present a synthesis of molecular investigation of microbial communities involved in various environmental bioprocesses, during the last 5 years in 3 laboratories. An important result of previous doctoral study (in France) and of current research projects (in Chile), is that targeting 16S rDNA is usually insufficient for an accurate characterization of functional populations in complex ecosystems, since the total community structure is only partially coupled to functional features of the bioreactors. In ammonia biofilters, the operating conditions (substrate pulses) acted as a driving force for community stratification as evidenced by DGGE, but the structure-function correlations were trickier to evidence. The sensibility of the molecular tool has to be adapted to the community complexity.
To get over this limitation, we developed a rational approach targeting specific functional genes coding for enzymes involved in the metabolic reactions of interest (i.e. degradation of a given contaminant), thus enabling to open the bioprocess black-box and reveal tighter coupling in various engineered ecosystems. For example, we demonstrated through quantitative PCR that the Ammonium and Nitrite Oxidizing Bacteria (AOB, NOB) abundances were strongly correlated with environmental stress and nitrification efficiency and stability in biofilters, and we highlighted the AOB and NOB adaptation to repeated load perturbations through memory effect. This French study case can be put in the perspective of molecular highlights from engineered ecosystems investigated in Chile, revealing system similarities and particularities: (i) resistance and resilience of methanotrophs exposed to load disturbance in methane biofilters, and (ii) conditions favoring the emergence and activity of specific microbial populations (phenol and H2S degraders) in methane producing digesters.
Palavras-chave: Microbial Ecology, Biofiltration, Anaerobic Digestion, Functional gene, Molecular biology