Microorganisms have historically been classified as obligate aerobes or anaerobes, facultative anaerobes, or microaerophiles, reflecting differences in respiratory strategies dictated by the use of ox...

Abstract. Over the past two decades, metagenomics has greatly expanded our understanding of microbial phylogenetic and metabolic diversity. However, most m

Microorganisms have historically been classified as obligate aerobes or anaerobes, facultative anaerobes, or microaerophiles, reflecting differences i…

Noteworthy — When first introduced to microbes, we quickly learn to divide them into aerobes and anaerobes. Then we qualify those titles with modifiers to yield such classes as facultative anaerobes, ...

Anaerobic microorganisms inhabit diverse anoxic environments and play a fundamental role in global biogeochemical cycles. Expanding our knowledge of these organisms offers the potential to transform o...

Microorganisms have historically been classified as obligate aerobes or anaerobes, facultative anaerobes, or microaerophiles, reflecting differences in respiratory strategies dictated by the use of oxygen and alternative electron acceptors. Recent discoveries provide evidence that a deviant strategy, the concurrent reduction of oxygen and other electron acceptors, is more widespread than previously thought. Such co-respiring bacteria employ hybrid metabolic strategies that extend models of electron acceptor use. In this review, we investigate mechanisms of co-respiration, summarize the biochemical components enabling parallel electron flow, and discuss the regulation of aerobic and anaerobic pathways under changing redox conditions. We also examine the evolutionary context of these strategies during the rise of oxygen on early Earth and outline experimental approaches needed to resolve co-respiration in individual cells.