Designation:D7818−12StandardTestMethodforEnumerationofProteolyticBacteriainFresh(Uncured)HidesandSkins1ThisstandardisissuedunderthefixeddesignationD7818;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoverstheenumerationofbacteriathatcanhydrolyzeprotein/collageninfresh(uncured)hidesandskins.Thistestmethodisapplicabletouncuredhidesandskins.1.2ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2D6715PracticeforSamplingandPreparationofFreshorSalt-Preserved(Cured)HidesandSkinsforChemicalandPhysicalTestsE691PracticeforConductinganInterlaboratoryStudytoDeterminethePrecisionofaTestMethodE177PracticeforUseoftheTermsPrecisionandBiasinASTMTestMethods3.SummaryofTestMethod3.1Samplesofuncuredhidesandskinsareseriallydilutedandplatedonagarcontainingcaseinfromskimmilk.Theplatesareincubatedunderaerobicconditionsat35°Cfor48h.Afterincubation,todeterminebacteriathatcanhydrolyzeprotein(proteolytic),theplatesarefloodedwithdiluteacidandthecoloniesshowingahaloarecounted.4.SignificanceandUse4.1Thistestmethodenumeratesproteolyticbacteria.Pro-teolyticbacteriahavebeenknowntocausedamagetohidesandskins.5.Apparatus5.1Incubator,3561°C.5.2Colonycounter—(notmandatory,buthighlyrecom-mended).5.3Sterilepipets.5.4Bentglassrods,sterile.5.5Stomacher,formixinginitialdilution.(Ifstomacherisunavailable,hand-mix.)5.6Balance.5.7Sterilepetridishes.5.8Autoclave(sterilizer).(Checktheeffectivenessofster-ilizationweekly.Forexample,placesporesuspensionsors...
