| In the Anthropocene, in which we now live, climate change is impacting most life on Earth. Microorganisms support the existence of all higher trophic life forms. To understand how humans and other life forms on Earth (including those we are yet to discover) can withstand anthropogenic climate change, it is vital to incorporate knowledge of the microbial 'unseen majority'. We must learn not just how microorganisms affect climate change (including production and consumption of greenhouse gases) but also how they will be affected by climate change and other human activities. This Consensus Statement documents the central role and global importance of microorganisms in climate change biology. It also puts humanity on notice that the impact of climate change will depend heavily on responses of microorganisms, which are essential for achieving an environmentally sustainable future.

Cryptic Sulfur Cycling Aerobic bacteria and ocean circulation patterns control the formation and distribution of oxygen-minimum zones at moderate depth in the oceans. These habitats host microorganisms that thrive on other metabolic substrates in the absence of oxygen—most commonly, metabolizing thermodynamically favorable nitrogen compounds like nitrate. Off the coast of Chile, however, Canfield et al. (p. 1375 , published online 11 November; see the Perspective by Teske ) suggest that bacteria may often reduce sulfate as well. Metagenomic sequencing revealed the presence of both sulfate-reducing and sulfide-oxidizing bacteria. With the coincidence of sulfate and nitrate reduction, the sulfur and nitrogen cycles may be intimately linked; for example, sulfate reduction could provide nitrogen-rich ammonium for bacteria that ultimately transform it into nitrogen gas.

CRISPR/Cas9 systems are a versatile tool for genome editing due to the highly efficient targeting of DNA sequences complementary to their RNA guide strands. However, it has been shown that RNA-guided Cas9 nuclease cleaves genomic DNA sequences containing mismatches to the guide strand. A better understanding of the CRISPR/Cas9 specificity is needed to minimize off-target cleavage in large mammalian genomes. Here we show that genomic sites could be cleaved by CRISPR/Cas9 systems when DNA sequences contain insertions (‘DNA bulge’) or deletions (‘RNA bulge’) compared to the RNA guide strand, and Cas9 nickases used for paired nicking can also tolerate bulges in one of the guide strands. Variants of single-guide RNAs (sgRNAs) for four endogenous loci were used as model systems, and their cleavage activities were quantified at different positions with 1- to 5-bp bulges. We further investigated 114 putative genomic off-target loci of 27 different sgRNAs and confirmed 15 off-target sites, each harboring a single-base bulge and one to three mismatches to the guide strand. Our results strongly indicate the need to perform comprehensive off-target analysis related to DNA and sgRNA bulges in addition to base mismatches, and suggest specific guidelines for reducing potential off-target cleavage.

Running title: OMZ community gene expression 35Keywords: nitrification, amoA, anammox, denitrification, nitrate reduction, crenarchaea, Nitrosopumilus, pyrosequencing monooxygenase genes, which, despite being represented by both bacterial and archaeal sequences in the community DNA, were dominated (>99%) by archaeal sequences in the RNA, suggesting a substantial role for archaeal nitrification in the upper OMZ. These data, as well as those describing other key OMZ metabolic processes (e.g., sulfur oxidation), highlight gene-65 specific expression patterns in the context of the entire community transcriptome, as well as identify key functional groups for taxon-specific genomic profiling. Modifications made to this revised manuscript are highlighted in green3

Vast expanses of oxygen-deficient and nitrite-rich water define the major oxygen minimum zones (OMZs) of the global ocean. They support diverse microbial communities that influence the nitrogen economy of the oceans, contributing to major losses of fixed nitrogen as dinitrogen (N 2 ) and nitrous oxide (N 2 O) gases. Anaerobic microbial processes, including the two pathways of N 2 production, denitrification and anaerobic ammonium oxidation, are oxygen-sensitive, with some occurring only under strictly anoxic conditions. The detection limit of the usual method (Winkler titrations) for measuring dissolved oxygen in seawater, however, is much too high to distinguish low oxygen conditions from true anoxia. However, new analytical technologies are revealing vanishingly low oxygen concentrations in nitriterich OMZs, indicating that these OMZs are essentially anoxic marine zones (AMZs). Autonomous monitoring platforms also reveal previously unrecognized episodic intrusions of oxygen into the AMZ core, which could periodically support aerobic metabolisms in a typically anoxic environment. Although nitrogen cycling is considered to dominate the microbial ecology and biogeochemistry of AMZs, recent environmental genomics and geochemical studies show the presence of other relevant processes, particularly those associated with the sulfur and carbon cycles. AMZs correspond to an intermediate state between two "end points" represented by fully oxic systems and fully sulfidic systems. Modern and ancient AMZs and sulfidic basins are chemically and functionally related. Global change is affecting the magnitude of biogeochemical fluxes and ocean chemical inventories, leading to shifts in AMZ chemistry and biology that are likely to continue well into the future.