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Bacterial degradation of organosulfonates plays an important role in sulfur recycling, and has been extensively studied. However, this process in anaerobic bacteria especially gut bacteria is little known despite of its potential significant impact on human health with the production of toxic H 2 S. Here, we describe the structural and biochemical characterization of an oxygen-sensitive enzyme that catalyzes the radical-mediated C-S bond cleavage of isethionate to form sulfite and acetaldehyde. We demonstrate its involvement in pathways that enables C2 sulfonates to be used as terminal electron acceptors for anaerobic respiration in sulfate- and sulfite-reducing bacteria. Furthermore, it plays a key role in converting bile salt-derived taurine into H 2 S in the disease-associated gut bacterium Bilophila wadsworthia . The enzymes and transporters in these anaerobic pathways expand our understanding of microbial sulfur metabolism, and help deciphering the complex web of microbial pathways involved in the transformation of sulfur compounds in the gut.

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Abstract-This paper demonstrates a flexible optical waveguide film with integrated optoelectronic devices (vertical-cavity surfaceemitting laser (VCSEL) and p-i-n photodiode arrays) for fully embedded board-level optical interconnects. The optical waveguide circuit with 45 micromirror couplers was fabricated on a thin flexible polymeric substrate by soft molding. The 45 couplers were fabricated by cutting the waveguide with a microtome blade. The waveguide core material was SU-8 photoresist, and the cladding was cycloolefin copolymer. A thin VCSEL and p-i-n photodiode array were directly integrated on the waveguide film. Measured propagation loss of a waveguide was 0.6 dB/cm at 850 nm.Index Terms-embedded optical interconnects, 45 micromirror coupler, printed circuit board (PCB), poly(dimethylsiloxane) (PDMS), soft molding, SU-8, topas, vertical-cavity surface-emitting laser (VCSEL), waveguide film.