Secretion of an inhibitor of follicle-stimulating hormone binding to receptor by the bacteria Serratia, including a strain isolated from porcine follicular fluid.
Bacterial growth in contaminated porcine follicular fluid (PFF) was associated with increased concentrations of a large molecular weight (Mr greater than 6000) inhibitor (FSH-BI) of 125I-FSH binding to calf testis membranes (Sluss and Reichert, 1983). We undertook to identify the bacteria and to determine if the inhibitor was a secretory product. Only one of 39 pure bacterial colonies isolated from PFF generated FSH-BI. The bacterium was tentatively identified as Serratia liquifaciens and was subsequently shown to also secrete FSH-BI when grown in synthetic culture media. Serratia liquifaciens from PFF secreted FSH-BI in a minimal culture medium containing only glucose as a carbon source. Other bacteria, including strains of Pseudomonas and Streptococcus did not secrete FSH-BI in either sterile PFF or synthetic culture media. Six strains of Serratia, obtained from the American Type Culture Collection, also secreted FSH-BI. FSH-BI secreted by Serratia liquifaciens was inactivated by heat (T 1/2 = 30 min at 60 degrees C), exposure to pH 2 (2 h at 25 degrees C) and was insoluble in ether, 75% acetone or 40% ammonium sulfate. Protease activity, using a casein substrate, was undetected in doses of FSH-BI which effectively (50%) inhibited 125I-FSH binding. Initial studies suggested that FSH-BI was due to effects on membranes rather than on the radioligand. These data demonstrate that Serratia liquifaciens isolated from PFF secretes a substance of Mr greater than 6000 which inhibits receptor binding of 125I-hFSH. Furthermore, the FSH-BI appears to be secreted constitutively by all (7) strains of Serratia tested.
D000818:Animals; D002417:Cattle; D005260:Female; D005640:Follicle Stimulating Hormone / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006727:Hormone Antagonists / Q000378:metabolism*; D066298:In Vitro Techniques; D007265:Inhibins; D008297:Male; D006080:Ovarian Follicle / Q000382:microbiology*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011962:Receptors, FSH; D012705:Serratia / Q000302:isolation & purification / Q000502:physiology*; D013552:Swine
D006727:Hormone Antagonists; D011956:Receptors, Cell Surface; D011962:Receptors, FSH; D007265:Inhibins; D005640:Follicle Stimulating Hormone