A unified compendium of prokaryotic and viral genomes from over 300 anaerobic digestion microbiomes

Background: The anaerobic digestion process degrades organic matter into simpler compounds and occurs in strictly anaerobic and microaerophilic environments. The process is carried out by a diverse community of microorganisms where each species has a unique role and it has relevant biotechnological applications since it is used for biogas production. Some aspects of the microbiome, including its interaction with phages, remains still unclear: a better comprehension of the community composition and role of each species is crucial for a cured understanding of the carbon cycle in anaerobic systems and improving biogas production. Results: The primary objective of this study was to expand our understanding on the anaerobic digestion microbiome by jointly analyzing its prokaryotic and viral components. By integrating 192 additional datasets into a previous metagenomic database, the binning process generated 11,831 metagenome-assembled genomes from 314 metagenome samples published between 2014 and 2022, belonging to 4,568 non-redundant species based on ANI calculation and quality verification. CRISPR analysis on these genomes identified 76 archaeal genomes with active phage interactions. Moreover, single-nucleotide variants further pointed to archaea as the most critical members of the community. Among the MAGs, two methanogenic archaea, Methanothrix sp. 43zhSC_152 and Methanoculleus sp. 52maCN_3230, had the highest number of SNVs, with the latter having almost double the density of most other MAGs. Conclusions: This study offers a more comprehensive understanding of microbial community structures that thrive at different temperatures. The findings revealed that the fraction of archaeal species characterized at the genome level and reported in public databases is higher than that of bacteria, although still quite limited. The identification of shared spacers between phages and microbes implies a history of phage-bacterial interactions, and specifically lysogenic infections. A significant number of SNVs were identified, primarily comprising synonymous and nonsynonymous variants. Together, the findings indicate that methanogenic archaea are subject to intense selective pressure and suggest that genomic variants play a critical role in the anaerobic digestion process. Overall, this study provides a more balanced and diverse representation of the anaerobic digestion microbiota in terms of geographic location, temperature range and feedstock utilization

ICP-MS determination of trace elements in the serum samples of healthy subjects using different sample preparation methods

The concentration of some trace elements of clinical importance was studied in blood serum samples of healthy subjects (n=19, mean age 22 +/- 4.5 years) to determine reference ranges for the healthy urban population in Eastern Hungary. A sample preparation method has been developed using closed-vessel microwave digestion with an oxidizing acid mixture (nitric acid and hydrogen peroxide) for multielemental analysis and atmospheric wet digestion with the aqueous solution of trimethyl amine (TMAH) for the measurement of aluminum. Contamination of the samples with Al was observed during acidic microwave digestion because of the chemicals used. Trace element concentrations in the samples were measured with ICP-TIS. The reference ranges obtained were (in mug/L): Al 0.98-1.74, Cr 42.8-59.3, Mn 2.27-5.05, Fe 1282-2050, Co 0.22-0.88, Ni 0.03-16.33, Cu 691-1003, Zn 591-1217, Sr 30.37-47.37, Mo 0.73-1.19, Cd 0.02-0.62, and Pb 0.02-2.70. The results were compared to the reference ranges actually used in the clinical practice, some of which are available in the literature. The effect of the applied digestion methods on the obtained individual results and average concentration ranges was also studied

Exceptionally well preserved late Quaternary plant and vertebrate fossils from a blue hole on Abaco, The Bahamas

We report Quaternary vertebrate and plant fossils from Sawmill Sink, a “blue hole” (a water-filled sinkhole) on Great Abaco Island, The Bahamas. The fossils are well preserved because of deposition in anoxic salt water. Vertebrate fossils from peat on the talus cone are radiocarbon-dated from ≈4,200 to 1,000 cal BP (Late Holocene). The peat produced skeletons of two extinct species (tortoise Chelonoidis undescribed sp. and Caracara Caracara creightoni) and two extant species no longer in The Bahamas (Cuban crocodile, Crocodylus rhombifer; and Cooper's or Gundlach's Hawk, Accipiter cooperii or Accipiter gundlachii). A different, inorganic bone deposit on a limestone ledge in Sawmill Sink is a Late Pleistocene owl roost that features lizards (one species), snakes (three species), birds (25 species), and bats (four species). The owl roost fauna includes Rallus undescribed sp. (extinct; the first Bahamian flightless rail) and four other locally extinct species of birds (Cooper's/Gundlach's Hawk, A. cooperii/gundlachii; flicker Colaptes sp.; Cave Swallow, Petrochelidon fulva; and Eastern Meadowlark, Sturnella magna) and mammals (Bahamian hutia, Geocapromys ingrahami; and a bat, Myotis sp.). The exquisitely preserved fossils from Sawmill Sink suggest a grassy pineland as the dominant plant community on Abaco in the Late Pleistocene, with a heavier component of coppice (tropical dry evergreen forest) in the Late Holocene. Important in its own right, this information also will help biologists and government planners to develop conservation programs in The Bahamas that consider long-term ecological and cultural processes