Therearetwokindsofcontaminantsonwormplates:1.Fungi:thesecontaminantscancomefromtheplatesorbacteria,soitisbesttoleaveplatesoutafterseedingforacoupleofdaystomakesurenofungalcoloniesgrowbeforeaddingworms.Ifastockgetsmold,justtransferthewormsregularlyfrompartsoftheplateawayfromthefungi;thewormswilloutgrowthemold.2.Non-OP50bacteria("slime").Noamountoftransferringthewormswillcurethis.Todecontaminateworms,make~0.6%NaOCl(i.e.12%vol/volofthecommercial5%solution),1.5MNaOH.Add50µltotheunseededportionofafreshplate.Place~10gravidadultsinthedrop.Canrecoverastrainfromasingleadultifnecessary.Theadultsandbacteriawilldie;theeggswilllive.Leavetheplaterightsideupovernight;thedropofliquidwillbeabsorbed,andlivehatchedwormswillcrawlontothebacteriallawn.Itisnecessarytomovethehatchedlarvaetoanewplatethenextday;afterthatbacteriaandfungusgeneratedfromresistantsporeswillspreadovertheplateandrecontaminatetheworms.Alternatively,aflamedspatulacanbeusedtosliceoffandremovethediscoloredportionoftheplatewheretheNaOCl/NaOHdropwas.AmethodtogetridofbacterialcontaminationrecentlyinventedbyNaAn:picksomecontaminatedwormstoastandardAmpicillinplate(75µg/ml)overnight,thenpickthewormsbacktoanNGMplateseededwithOP50thenextday.Thisseemstoworkwell,isquickandeasy,andperhapsthesuperiormethod,especiallyforsickstrainsthatdon"tsurvivethebleach/NaOHtreatmentwell.Philosophy:somepeoplealwaysworkwithcontaminatedstrains.However,ifyousimplycleanstrainsupeverytimeassoonastheybecomecontaminated,it"salmostnoefforttoalwayshaveclean,healthyworms.