Bacteriological composition and structure of granular sludge adapted to different substrates

Abstract

The bacteriological composition and ultrastructure of mesophilic granular methanogenic sludge from a large-scale Upflow Anaerobic Sludge Blanket reactor treating wastewater from a sugar plant and of sludge granules adapted to ethanol and propionate were studied by counting different bacterial groups and by immunocytochemical methods. Propionate-grown granular sludge consisted of two types of clusters, those of a rod-shaped bacterium immunologically related to Methanothrix soehngenii and those consisting of two different types of bacteria with a specific spatial orientation. One of these bacteria reacted with antiserum against Methanobrevibacter arboriphilus AZ, whereas the other is most likely a propionate-oxidizing bacterium immunologically unrelated to Syntrophobacter wolinii. Sludge granules obtained from the large-scale Upflow Anaerobic Sludge Blanket reactor and granules cultivated on ethanol did not show the typical spatial orientation of bacteria. Examination of the bacterial composition of the three types of granules by light and electron microscopy, the most-probable-number method, and by isolations showed that M. arboriphilus and M. soehngenii were the most abundant hydrogenotrophic and acetoclastic methanogens in propionate-grown sludge. Methanospirillum hungatei and Methanosarcina barkeri predominated in ethanol-grown granules, whereas many morphotypes of methanogens were abundant in granules from the full-scale reactor.

Metabolic, Phylogenetic, and Ecological Diversity of the Methanogenic Archaea

“…129,130 Methanosaeta perform better at high feeding-rate digestors, such as an upward-flow anaerobic sludge blanket (UASB), presumably due to their efficient adhesion and granulation. 131,132 In contrast, Methanosarcina are more sensitive to turbulence and shear, and they frequently dominate in fixed-and stirred-tank digestors. 133 The H 2 partial pressures in anaerobic digestors range from 2 Pa to 1200 Pa. 129 Low H 2 levels indicate efficient hydrogenotrophic methanogenesis and are usually associated with stable performance.…”

Microbial community structure and dynamics in anaerobic fluidized‐bed and granular sludge‐bed reactors: influence of operational temperature and reactor configuration

“…We propose that the better flexibility and adaptability of the IFB biomass to low temperature might originate from the spatial arrangement of fixed fluidized biomass that developed in the IFB (Fig. S1) playing an important role in differences in transfer of intermediates and optimal degradation of substrates (Grotenhuis et al, 1991). At low temperatures, the viscosity of effluents increases and, therefore, the diffusion of soluble compounds will drop, particularly in sludge bed reactors that become less easily mixed (Lettinga et al, 2001).…”

Methanogenesis from acetate: a comparison of the acetate metabolism in Methanothrix soehngenii and Methanosarcina spp.

“…The degradation of acetate by acetoclastic methanogens in these ecosystems prevents acidification of the environment [9,10]. Therefore, these systems have low acetate concentrations under steady-state conditions [9,10,[40][41][42]. Methanothri.x is one of the main microbial constituents in well-operating technical systems, such as anaerobic contact reactors and up-flow anaerobic sludge blanket (UASB) reactors [41][42][43].…”

“…Therefore, these systems have low acetate concentrations under steady-state conditions [9,10,[40][41][42]. Methanothri.x is one of the main microbial constituents in well-operating technical systems, such as anaerobic contact reactors and up-flow anaerobic sludge blanket (UASB) reactors [41][42][43]. The pre- In Table 1, an overview is presented of the physiological properties of both Methanosarcina and Methanothrix.…”

“…Comparing these different physiological properties, it can be seen that Methanothrix is favoured at low acetate concentrations [42][43][44][45].…”