Fuentes, L. | Search bioRxiv

bioRxiv2021

Potentialities of biotechnological recovery of hydrogen and short- and medium-chainorganic acids from the co-fermentation of cheese whey and Yerba Mate (Ilexparaguariensis) waste

Co-fermentation of cheese whey (CW) and thermal-alkaline pre-treated Yerba Mate (Ilex paraguariensis) waste (YMW) was performed aiming to produce biohydrogen and/or short- and medium-chain organic acids. Central Composite Designs (CCD) was chosen as the experimental design for evaluating the combinations of three independent variables namely YMW concentration, pH and inoculum concentration in hydrogen yield (H2Y; response variable). The increase of inoculum and YMW concentrations had positive effect in biohydrogen production and yield (H2Ymax of 1.35 mMH2.g-1 VS added) whereas the initial pH had no significant effect on it. Hydrogen was produced as a coproduct to butyrate mainly. Acetate from homoacetogenesis was accounted in all conditions evaluated. The CCD also indicated operating conditions to produce moderate-to-high concentrations of short and medium-chain organic acids such as butyrate (~135 mM), caproate (~45 mM) and lactate (~140 mM). 16S rRNA gene sequences analysis revealed five groups of microorganisms related to hydrogen, lactate and caproate production, ethanol-hydrogen co-production and hydrogen consumption. HighlightsO_LICo-fermentation improved hydrogen production in up 7.5-folds compared to the sole CW-fed system. C_LIO_LIThe initial pH had no effect on hydrogen-producing batch reactors. C_LIO_LIHydrogen was produced as a coproduct to butyrate. C_LIO_LIDesign of experiment indicated operating conditions to the production of lactate and caproate. C_LI

biochemistry↗

bioRxiv2020

Population sequencing data reveal a compendium of mutational processes in human germline

Mechanistic processes underlying human germline mutations remain largely unknown. Variation in mutation rate and spectra along the genome is informative about the biological mechanisms. We statistically decompose this variation into separate processes using a blind source separation technique. The analysis of a large-scale whole genome sequencing dataset (TOPMed) reveals nine processes that explain the variation in mutation properties between loci. Seven of these processes lend themselves to a biological interpretation. One process is driven by bulky DNA lesions that resolve asymmetrically with respect to transcription and replication. Two processes independently track direction of replication fork and replication timing. We identify a mutagenic effect of active demethylation primarily acting in regulatory regions. We also demonstrate that a recently discovered mutagenic process specific to oocytes can be localized solely from population sequencing data. This process is spread across all chromosomes and is highly asymmetric with respect to the direction of transcription, suggesting a major role of DNA damage.

genetics↗