Out Of The Abyss
During these fights for survival, the PCs slowly learn that the underdark is even more dangerous than usual. Even the relatively stable denizens of the underdark seem to be afflicted with a creeping madness that pervades the settlements they visit. Eventually learning that the 8 demon lords of the abyss have been somehow freed and are now carving out chunks of the underdark to form their new abyssal domains.
Out of the Abyss
Appendix D of the book outlines the 8 demons that need to be pushed back into the abyss from which they came. Each get a two page spread, allowing each to get their own flavor and personality. (Is personality the word I am looking for when describing a demon? How about grotesqueness? Psychoanalysis? Eh, whatever. The artwork is amazing!)
Natural products have traditionally been discovered through the screening of culturable microbial isolates from diverse environments. The sequencing revolution allowed the identification of dozens of biosynthetic gene clusters (BGCs) within single bacterial genomes, either from cultured or uncultured strains. However, we are still far from fully exploiting the microbial reservoir, as most of the species are non-model organisms with complex regulatory systems that can be recalcitrant to engineering approaches. Genomic and metagenomic data produced by laboratories worldwide covering the range of natural and artificial environments on Earth, are an invaluable source of raw information from which natural product biosynthesis can be accessed. In the present work, we describe the environmental distribution and evolution of the abyssomicin BGC through the analysis of publicly available genomic and metagenomic data. Our results demonstrate that the selection of a pathway-specific enzyme to direct genome mining is an excellent strategy; we identified 74 new Diels-Alderase homologs and unveiled a surprising prevalence of the abyssomicin BGC within terrestrial habitats, mainly soil and plant-associated. We also identified five complete and 12 partial new abyssomicin BGCs and 23 new potential abyssomicin BGCs. Our results strongly support the potential of genome and metagenome mining as a key preliminary tool to inform bioprospecting strategies aimed at the identification of new bioactive compounds such as -but not restricted to- abyssomicins.
The abyssomicins are an actively growing family of small spirotetronate natural products with a polyketide backbone and a C11 central ring system that has been widely studied due to the unique structural features and bioactivities that some of its members exhibit. Abyssomicin biosynthesis occurs in a variety of hosts isolated from different ecosystems. The first abyssomicins (B-D) were discovered in 2004 during the screening of 930 actinomycetes extracts in a successful attempt to find antibacterial compounds targeting folate biosynthesis. Those abyssomicins were fermentation products of the marine actinomycete Verrucosispora maris AB-18-032T, later reclassified as Micromonospora maris AB-18-032T (Nouioui et al., 2018), isolated from sediments of the Sea of Japan (Riedlinger et al., 2004). Years later, other research groups found new abyssomicins produced by soil isolates of Streptomyces sp. HKI0381, Streptomyces sp. CHI39, recently classified as Streptomyces abyssomicinicus CHI39T (Komaki et al., 2019), and Streptomyces sp. Ank 210, in Senegal, Mexico and Germany, respectively (Niu et al., 2007; Igarashi et al., 2010; Abdalla et al., 2011). After that, the production of abyssomicins was again reported in marine isolates: Verrucosispora sp. MS100128 (Wang et al., 2013), Streptomyces sp. RLUS1487 (León et al., 2015), and Verrucosispora sp. MS100047 (Huang et al., 2016). Finally, the last abyssomicins found were synthesized by the soil Streptomyces sp. LC-6-2 (Wang et al., 2017) and the marine Streptomyces koyangensis SCSIO 5802 (Song et al., 2017; Huang et al., 2018). During the review process of this paper, abyssomicin Y was discovered in fermentation extracts of the marine Verrucosispora sp. MS100137 (Zhang et al., 2020) (Supplementary Table S1).
(A) Abyssomicin BGC (aby) of Micromonospora maris AB-18-032. (B) Partial abyssomicin BGC of Verrucosispora sp. MS1000047. (C) Abyssomicin BGC (abs) of Streptomyces sp. LC-6-2. (D) Neoabyssomicin/abyssomicin BGC (abm) of Streptomyces koyangensis SCSIO 5802. (E) Abyssomicin BGC (abi) of S. abyssomicinicus. Gene names in black are common to aby, abs, and abm BGCs. Blue font represents genes present only in M. maris AB-18-032, gray font represents genes present only in Streptomyces sp. LC-6-2 and light blue font represent genes unique to S. koyangensis SCSIO 5802. In maroon font appear those genes that appear both in aby and abs BGCs, in light brown those genes that appear both in aby and abm BGCs and in yellow those genes that appear both in abs and abm BGCs.
After that, the discovery of abyssomicins M-X as fermentation products of Streptomyces sp. LC-6-2 led to the description of a new abyssomicin BGC (abs). This cluster consists of 30 genes disposed along 62 kb and presents homologs to most of the genes within aby BGC (Supplementary Table S12) but displays also two unique regulators (absC1 and absC2) and a set of four new tailoring genes (absG1, absG2, absI, and absJ) (Wang et al., 2017) (Figure 1C). A third cluster responsible for neoabyssomicin/abyssomicin biosynthesis (abm) was identified in S. koyangensis SCSIO 5802. Composed of 28 genes distributed along 63 kb, it presents five genes (abmK, abmL, abmM, abmN, and abmE2) with no apparent homologous counterparts in the aby cluster and two more (abmJ and abmG) that appear to be in abs BGC but not in aby BGC (Figure 1D and Supplementary Table S11) (Tu et al., 2018). The latest abyssomicin BGC (abi) was found in S. abyssomicinicus CHI39 and is almost identical to abm BGC (Figure 1E and Supplementary Table S14) (Komaki et al., 2019).
Habitat distribution of (A) the abyssomicin producing bacteria isolated and reported in the literature until this manuscript was written. (B) Metagenomes containing AbyU homologs. (C) Metagenomes containing AbsU homologs. (D) Metagenomes containing AbmU homologs.
The archmage of Menzoberranzan, Gromph Baenre, ushered in an invasion of abyssal lords in a failed attempt to summon and bind his spider-goddess, Lolth. Now the demon lords rampage throughout the Underdark and must be stopped at all costs!
"Times are still difficult and the level of completed deals in Q3 2009 is still significantly below the level of Q3 2008, which would suggest that the climb out of the abyss may be in progress but with some way to go," he said. 041b061a72