Response of microbial adhesives and biofilm matrix polymers to chemical treatments as determined by interference reflection microscopy and light section microscopy.

H2Stosolid surfaces were investigated todetermine whether differences between cellsurface adhesives andbioffim matrix polymers could bedetected. Twooptical techniques, i.e., interference reflection microscopy (IRM)andlight section microscopy (LSM), were usedtocompare theresponsesofthetwotypesofpolymer totreatment withelectrolytes, dimethyl sulfoxide (DMSO), andTween20.Toevaluate initial adhesive polymers, P.fluorescens H2Scellswere allowed toattach toglass coverslip surfaces andwereimmediately examined withIRM,andtheir responsetochemical solutions was tested. WithIRM,changes incell-substratum separation distance between 0andca.100nm are detectable aschanges inrelative light intensity oftheimage;acontraction ofthepolymer wouldbedetected as adarkening oftheimage, whereas expansion would appearasimagebrightening. Toevaluate theintercellular polymer matrix inbioffilms, 3-day-old bioffilms wereexposed tosimilar solutions, andtheresultant change in biofflm thickness was measured withLSM,which measuresfilmthicknesses between 10and1,000 ,um.The initial adhesive andbiofllm polymers were similar inthatbothappeared tocontract whentreated with electrolytes andtoexpand whentreated withTween20.However, withDMSO treatment, theinitial adhesive polymer appeared tocontract, whereas there was no change inthickness ofthebiofllm polymer. Theseresults indicate thatbothpolymers bearacidic groupsandthusactelectrostatically withcations andareabletoenter into hydrophobic interactions. Differences intheir responsetoDMSO could beduetotheclose proximity ofthe glass surface ortodifferences instructure ofthetwopolymers. Bothbacterial adhesion tosurfaces andthesubsequent formation ofmicrobial biofilms haveserious implications for a numberofindustrial applications inaqueous environments.Thedevelopment ofmulticellular biofilms on submergedman-madestructures suchasdrilling platforms and shiphulls isthefirst obvious stageinthefouling ofthese structures, whichcan progresstothepointwherecostly cleaning or replacement isneeded. On heatexchangers, even thinmicrobial films cause a serious decrease inefficiency ofheattransfer. Biofilm formation isinitiated whenbacteria aredeposited froman aqueous phaseontotheattachment substratum. Thesebacteria appear toadheretothesurface by the adsorption ofcell surface adhesive polymers, whichmay be polysaccharides andmay occurasthinmicrocapsular coats (9)or asthicker capsules (22). Cellsurface proteins (6,10, 18)or possibly lipids (26)may alsobeinvolved. After attachment, ifnutrients areavailable, thebacteria will grow andmultiply, whileadditional cells may attach fromthe adjacent water, so thatmicrocolonies develop on thesurface. During this period further production andaccumulation ofextracellular polymers occur(4). Ascell numbersincrease further, theextracellular polymers forma matrix inwhich thecells inthemultilayer biofilm areembedded. Thefunctions oftheinitial adhesives andthebiofilm matrix polymers aresomewhatdifferent. Theadhesive binds thecell toa distinct andoftennonhydrated andnonpopu