Dominance of Hydrogenotrophic Methanogens at the Peak of Biogas Production in Thalassic Digesters
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- Marquez, G.P.B., Reichardt, W.T., Azanza, R.V. et al. Waste Biomass Valor (2015) 6: 201. doi:10.1007/s12649-014-9325-4
Marine biomasses used in biogasification system are usually treated as terrestrial feedstock after salt removal. However, biogas production of sea wrack biomass run under thalassic (marine) conditions, and seeded with different inocula [cow manure (CM), marine sediment (MS) and sea wrack-associated (SWA) microflora] showed the potential for cheaper alternative to freshwater utilization (terrestrial conditions). To understand how methane yield is affected by the different inoculants under thalassic conditions, methanogenic communities in these digesters (CM, MS, SWA) were quantified using double-labeled oligonucleotide probes to a modified fluorescence in situ hybridization at the peak of biogas production. Total targeted methanogens were highest in SWA (1.51 ± 0.53 × 107 cells ml−1) while lowest in CM (1.79 ± 0.20 × 106 cells ml−1). Among all types of targeted methanogens, hydrogenotrophs (Methanobacteriales and Methanomicrobiales) dominated in all digesters (CM 73.2 ± 7 %, MS 58.4 ± 8.0 %, SWA 61.2 ± 5.4 %). Moreover, MS showed mixotrophic Methanosarcinaceae (30.2 ± 8.1 %) co-dominance, suggesting that their population could have influenced the higher methane yield in MS.