Cellulosomes localise on the surface of membrane vesicles from the cellulolytic bacterium Clostridium thermocellum. Issue 12 (1st July 2019)

• Record Type: Journal Article
• Authors: Ichikawa, Shunsuke; Ogawa, Satoru; Nishida, Ayami; Kobayashi, Yuzuki; Kurosawa, Toshihito; Karita, Shuichi
• Is Part Of: FEMS microbiology letters. Volume 366:Issue 12(2019)
• Publication Date: 2019-07-01
• Subjects: cellulosic biomass -- Clostridium thermocellum -- cellulosome -- membrane vesicle; Microbiology -- Periodicals; 579
• DOI: 10.1093/femsle/fnz145
• Languages: English
• ISSNs: 0378-1097

Abstract

ABSTRACT: Membrane vesicles released from bacteria contribute to cell–cell communication by carrying various cargos such as proteins, nucleic acids and signaling molecules. Cellulolytic bacteria have been isolated from many environments, yet the function of membrane vesicles for cellulolytic ability has been rarely described. Here, we show that a Gram-positive cellulolytic bacterium Clostridium thermocellum released membrane vesicles, each approximately 50–300 nm in diameter, into the broth. The observations with immunoelectron microscopy also revealed that cellulosomes, which are carbohydrate-active enzyme complexes that give C . thermocellum high cellulolytic activity, localized on the surface of the membrane vesicles. The membrane vesicles collected by ultracentrifugation maintained the cellulolytic activity. Supplementation with the biosurfactant surfactin or sonication treatment disrupted the membrane vesicles in the exoproteome of C . thermocellum and significantly decreased the degradation activity of the exoproteome for microcrystalline cellulose. However, these did not affect the degradation activity for soluble carboxymethyl cellulose. These results suggest a novel function of membrane vesicles: C . thermocellum releases cellulolytic enzymes on the surface of membrane vesicles to enhance the cellulolytic activity of C . thermocellum for crystalline cellulose. Abstract : A bacterium Clostridium thermocellum releases cellulolytic enzymes on the surface of membrane vesicles to enhance the cellulolytic activity for crystalline cellulose