Bacterial communities in thermophilic H2-producing reactors investigated using 16S rRNA 454 pyrosequencing

Abstract

In this study, the composition and diversity of the bacterial community in thermophilic H2-producing reactors fed with glucose were investigated using pyrosequencing. The H2-producing experiments in batch were conducted using 0.5 and 2.0 g l(-1) glucose at 550 °C. Under the two conditions, the H2 production and yield were 1.3 and 1.6 mol H2 mol glucose(-1), respectively. Acetic, butyric, iso-butyric, lactic and propionic acids were detected in the two reactors. The increase in substrate concentration favored a high H2 yield. In this reactor, a predominance of acetic and iso-butyric acids, 27.7% and 40%, were measured, respectively. By means of pyrosequencing, a total of 323 and 247 operational taxonomic units were obtained, with a predominance of the phylum Firmicutes (68.73-67.61%) for reactors with 0.5 and 2.0 g l(-1) glucose, respectively. Approximately 40.55% and 62.34% of sequences were affiliated with Thermoanaerobacterium and Thermohydrogenium, microorganisms that produce H2 under thermophilic conditions.

Bioconversion of crude glycerol from waste cooking oils into hydrogen by sub-tropical mixed and pure cultures

“…Shannon index of 1.033 indicated the community diversity while Chao estimators represent the community richness of 772 [38]. Ratti et al (2015) [39] studied the composition and diversity of the bacterial community, obtained from a granular sludge from a thermophilic UASB reactor used in the treatment of stillage from sugarcane (the same inoculum source as in the present study), in reactors, during the H 2 -production fed with glucose incubated at 55 C using pyrosequencing. The experiments were conducted using 0.5 and 2.0 g L À1 glucose.…”

“…It was observed that the curve reached a plateau after 200 sequences, showing stabilization. According to Ratti et al (2015) [39], it suggests that the number of sequences was sufficient to cover the whole bacterial diversity. In addition, according to Xie et al (2016) [38], as the curve become relatively flat as the number of sequences increased, it is guaranteed that there is rationality and accuracy of the results.…”

“…The period of seven days was enough for the entire exponential phase of fermentative microorganisms growth to be achieved [40] and, at the same time, it inhibit the activity of the methanogenic microorganisms, since they require a period of more than 15 days for its development [41], [42]. The inoculum that underwent a pretreatment process, obtained from granular methanogenic sludge and environmental samples, such as soil, water, among others, used for the biological H 2 -production, presents a reduction in the relative abundance of species with consequent low OTU ratio [39], [43].…”

“…2A). According to the literature, Firmicutes phylum encompasses the main microorganisms that produce H 2 [39,44]. Microorganisms of the phylum Firmicutes performed the most important role in the fermentation process of the organic matter decomposition [45].…”

Evaluation of Faecalibacterium 16S rDNA genetic markers for accurate identification of swine faecal waste by quantitative PCR

“…With the development of new technologies, 454 pyrosequencing has become a more powerful tool that can be used to analyse millions of nucleic acid sequences and generate a vast amount of data in a shorter time with a low level of error (0.1%) (Ratti et al, 2015). Sequence analysis of their 16S rRNA gene has enabled researchers to characterise previously unknown isolates and increase the current understanding of their distribution in the intestinal flora of different animals (Hold et al, 2002;Vaughan et al, 2015).…”