Lessons learned from the microbial ecology resulting from different inoculation strategies for biogas production from waste products of the bioethanol/sugar industry

Abstract

BackgroundDuring strategic planning of a biogas plant, the local availability of resources for start-up and operation should be taken into consideration for a cost-efficient process. Because most bioethanol/sugar industries in Brazil are located in remote areas, the use of fresh cattle manure from local farms could be a solution for the inoculation of the biogas process. This study investigated the diversity and dynamics of bacterial and archaeal communities and the performance of biogas reactors inoculated with manure and a mixed inoculum from different biogas reactors as for a controlled start-up until steady state.ResultsLaboratory-scale biogas reactors were fed semi-continuously with sugarcane filter cake alone (mono-digestion) or together with bagasse (co-digestion). At the initial start-up, the reactors inoculated with the mixed inoculum displayed a less diverse taxonomic composition, but with higher presence of significant abundances compared to reactors inoculated with manure. However, in the final steady state, the communities of the differently inoculated reactors were very similarly characterized by predominance of the methanogenic genera Methanosarcina and Methanobacterium, the bacterial families Bacteroidaceae, Prevotellaceae and Porphyromonadaceae (phylum Bacteroidetes) and Synergistaceae (phylum Synergistetes). In the mono-digestion reactors, the methanogenic communities varied greater than in the co-digestion reactors independently of the inoculation strategy.ConclusionThe microbial communities involved in the biogas production from waste products of the Brazilian bioethanol/sugar industry were relatively similar and stable at the reactor’s steady phase independently of the inoculum source (manure or mixed inoculum). Therefore, the locally available manure can be used as inoculum for start-up of the biogas process, since it also contains the microbial resources needed. The strong fluctuation of methanogenic communities in mono-digestion reactors indicates higher risk of process instability than in co-digestion reactors.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0548-4) contains supplementary material, which is available to authorized users.

Targeting Bacteria and Methanogens To Understand the Role of Residual Slurry as an Inoculant in Stored Liquid Dairy Manure

“…As archaeal communities in rumen and manure environments are generally dominated by methanogens (39) and many of them can establish in both environments (12), storage of dairy slurry might not result in significant shifts in the diversity of archaea or methanogens (40). Indeed, an earlier study (41) identified similar methanogenic archaeal communities from fresh diary manure and a mixed inoculum obtained from different biogas reactors, although with a higher abundance in the latter, which is consistent with the current study. The relatively higher diversity of bacteria in RS than in fresh manure was not expected, but the source of RS might have influenced the diversity.…”

Ammonium Chloride vs Urea‐Induced Ammonia Inhibition of the Biogas Process Assessed by Stable Isotope Analysis

“…in a plot showing also the δ 13 C CH4 and δ 2 H CH4 values. The combination of carbon and hydrogen isotope data sometimes allows a more detailed characterization of the potential dominant methanogenic pathways during biogas reactor experiments , . The δ 2 H CH4 values in the batch experiment ranged between −271 and −319 ‰ and clearly differed from the values of the maize silage mono‐digesting CSTR data scattered in a narrow range between −267 and −280 ‰.…”

Beyond Sugar and Ethanol Production: Value Generation Opportunities Through Sugarcane Residues

“…In countries with few AD plants separated by long distances such as Brazil, arranging proper inocula is difficult. This was successfully addressed by the evaluation of reactor inoculation with fresh cattle manure as a locally available, alternative inoculum (Janke et al, 2016c;Leite et al, 2016). Animal manure is rich in microorganisms from animal digesting system, as well important macronutrients and trace elements (Feng et al, 2020).…”