Psychrophilic methanogenic community development during long-term cultivation of anaerobic granular biofilms

Abstract

Granular biomass was temporally sampled from a cold (4-15 1C) anaerobic bioreactor, which was inoculated with mesophilic biomass and used to treat industrial wastewater in a long-term (3.4 year) study. Data from 16S rRNA gene clone libraries, quantitative PCR and terminal restriction fragment length polymorphism analyses indicated that microbial community structure was dynamic, with shifts in the archaeal and bacterial communities' structures observed following start-up and during temperature decreases from 15 to 9.5 1C (phase 1). Specifically, the relative abundance of architecturally important Methanosaeta-like (acetoclastic) methanogens decreased, which was concomitant with granule disintegration and the development of a putatively psychrophilic hydrogenotrophic methanogenic community. Genetic fingerprinting suggested the development of a psychroactive methanogenic community between 4 and 10 1C (phase 2), which was dominated by acetogenic bacteria and Methanocorpusculum-like (hydrogenotrophic) methanogens. High levels of Methanosaeta-like acetoclastic methanogens and granular biofilm integrity were maintained during phase 2. Overall, decreasing temperature resulted in distinctly altered microbial community structure during phase 1, and the development of a less dynamic psychroactive methanogenic consortium during phase 2. Moreover, psychrophilic H 2 -oxidizing methanogens emerged as important members of the psychroactive consortia after 41200 days of low-temperature cultivation. The data suggest that prolonged psychrophilic cultivation of mesophilic biomass can establish a well-functioning psychroactive methanogenic consortium, thus highlighting the potential of low-temperature anaerobic digestion technology.

Effect of Seasonal Temperature on the Performance and on the Microbial Community of a Novel AWFR for Decentralized Domestic Wastewater Pretreatment

“…Hydrogenotrophic genera (>63.7%) made up a large portion of the archaeal community in winter. These findings were in line with the previous observations of methanogen population shifts to favor hydrogen utilization under low temperatures [25,[41][42][43]. It might be explained that lower temperature in winter affected the microbial membrane fluidity and inhibited the utilization of acetate than H 2 [44].…”

“…It might be participating in the degradation of amino acids and some refractory organic matters [56][57][58]. The genus Smithella, which could degrade propionate to acetate [42,59], was dominant in start-up (3.13%) and winter (3.5%), and this was probably one of the reasons of acetate accumulation. The genus Acinetobacter was observed in autumn and winter, and was probably involved in the oxidation of organic matter or sulfides [13,60].…”

A Functional Approach To Uncover the Low-Temperature Adaptation Strategies of the Archaeon Methanosarcina barkeri

“…In contrast, low levels of Methanosarcinaceae have been found in well-functioning LTAD systems (14,22). For example, in one study this group was detected below the quantification limit of the 16S rRNA gene assay, whereas Methanosaetaceae comprised 75% of total measured methanogenic 16S rRNA gene concentrations (23).…”

“…Acetoclastic (acetate decarboxylation) methanogenesis has been recorded as being an important methanogenic pathway in low-temperature environments, including bioengineered systems (14). The order Methanosarcinales includes the only two known acetoclastic families, the Methanosaetaceae and the Methanosarcinaceae.…”

“…In many LTAD studies, Methanosaetaceae have been the predominant acetoclastic methanogenic group, with their abundance positively correlated to process efficiency (19)(20)(21) and granular sludge integrity (14). In contrast, low levels of Methanosarcinaceae have been found in well-functioning LTAD systems (14,22).…”