Bacteria utilize the nitrogen fixation-like metalloenzyme, Methylthio-Alkane Reductase (MAR), when sulfate is limited for the acquisition of sulfur from Volatile Organic Sulfur Compounds. Initially it was discovered that reductive cleavage of methylthio-ethanol liberates methanethiol and ethylene, and reductive cleavage of dimethylsulfide liberates methanethiol and methane from these biologically and environmentally significant compounds. Notably the liberated methanethiol is utilized by the organism for methionine synthesis as an alternative to sulfate reduction, and the liberated ethylene or methane hydrocarbon is released into the environment. For catalysis of reductive carbon-sulfur bond cleavage, the native MAR of Rhodospirillum rubrum is a two-component system composed of MarH ATP-dependent reductase and MarDK catalytic core whose architecture parallels nitrogenase. A small accessory protein, MarS, complexes with MarDK and functions in MAR activity regulation during sulfate influx and darkness. MarDK possesses complex metallocofactors resembling but not identical to nitrogenase P- and iron-only M-clusters with respect to metallocofactor identity or coordination. These metallocofactors are designated as the P-cluster-like mar1- and M-cluster-like mar2-clusters. They exhibit electronic features similar to the iron-only nitrogenase under turnover, and remarkably are matured by MarB, which is a homolog of NifB present in MAR gene clusters, or the bona fide nitrogenase NifB. Finally, purified MAR has a broad substrate specificity for methylthio-alkane compounds (CH3-S-R), capable of cleaving alkyl chains from the sulfur atom up to 10 carbons in length. However, MAR has low activity with thio-alkanes (HS-R) and larger alkyl-thioethers (R-S-R') also found in the environment. Altogether, this suggests a broader scope of reactivity, mechanisms, and regulation in microbial metabolism for the nitrogenase-like family of enzymes than previously considered.