Isolation and characterization of Linocin M18, a bacteriocin produced by Brevibacterium linens

Abstract

Brevibacterium linens M18, isolated from red smear cheese, produces a substance that inhibits the growth of Listeria spp. and several coryneform and other gram-positive bacteria. No gram-negative bacteria were inhibited. The substance is heat labile, sensitive to proteolytic enzymes, and stable between pH 3 and 12. High levels of this bacteriocin, named Linocin M18, were obtained in the stationary growth phase. Linocin M18 was purified by ultrafiltration, ultracentrifugation, and gel filtration chromatography. In its native form, it is a proteinaceous aggregate with a high molecular weight. Fractions with Linocin M18 activity contained particles of 20 to 30 nm in diameter. The bacteriocin consists of a single protein subunit with a molecular mass of 31 kDa and an isoelectric point of 4.5. N-terminal sequence analysis yielded Met-Asn-Asn-Leu-Tyr-Arg-Glu-Leu

A virus capsid‐like nanocompartment that stores iron and protects bacteria from oxidative stress

“…One subset of encapsulin operons also code for a dyedecolorizing peroxidase (DyP) or for a ferritin-like protein (Flp), which was taken to suggest a role in the oxidative-stress response (Sutter et al, 2008), now amply confirmed in the M. xanthus system. However, other encapsulin nanocompartments have been suggested to perform different functions, including antibacterial activity in Brevibacterium linens (Valdes-Stauber & Scherer, 1994), proteolytic activity in T. maritima (Hicks et al, 1998), and lignin degradation activity in Rhodococcus jostii RHA1 (Rahmanpour & Bugg, 2013).…”

Iron-sequestering nanocompartments as multiplexed Electron Microscopy gene reporters

“…We then demonstrate that QtEnc can be robustly differentiated from the non-intermixing encapsulin of Myxococcus xanthus 17 (Mx,~32 nm) via a deep-learning model, thus enabling automated multiplexed EM gene reporter imaging in mammalian cells. Encapsulins are a class of proteinaceous spherical nanocompartments naturally occurring in bacteria and archaea, so far described as icosahedral structures with either T=1 (60 subunits,~18 nm diameter) or T=3 (180 subunits,~30 nm) symmetry, which can encapsulate cargo proteins with a wide range of functions [18][19][20][21] . It has also been shown that foreign cargos such as fluorescent proteins or enzymes can be genetically targeted into the encapsulin lumen in bacterial and mammalian hosts [22][23][24][25][26] .…”

High Genetic Potential for Proteolytic Decomposition in Northern Peatland Ecosystems

“…Their high abundance within peatland metagenomes, and in the more N-limited fen environment, along with physiological selection under low N concentration reflects a distinct ecological niche for these organisms in peatlands. Finally, bacterial protease gene family U56 (formerly linocin M18 (69)) has been largely studied within the context of dairy fermentation but is identified as a key enzyme for the decomposition of milk proteins by Brevibacterium linens (69). They may play a similar role within peatland by targeting proteinaceous material though further investigation is necessary.…”