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Methodsofscreening,culturing,improvementandstorageofmicroorganisms...
determinationofgenetichomology-basedoncomparison
ofsimilaritiesoflargesectionsofDNAisolatedfrom
protoplasts;theresultsoftheaboveresearchwereusedin
taxonomy-todescribetaxonomicunitsandtoestablishan
afnityofmicroorganisms(especiallyfungi);
studiesofmetabolicprocesses(includingthebiosynthesis
ofcertainantibioticsandmycotoxinsandthe
transformationofsteroidcompounds),wherethecellwall
mayconstituteabarrierthatsignificantlylimitstherate
ofsubstrateintakeintothecellorsecretionofproductinto
thegrowthenvironment;
increaseintheefciencyofmicrobialmetabolicprocesses
ofhighcommercialsignificance(so-calledstrain
improvement),inwhichmethodsofmutagenisation,
recombinationandfusionofprotoplastsareused
(additionaldataareprovidedinSection1.6).
Themethodsdevelopedsofarforremovingthecellwallto
obtainprotoplastsarebasedontheuseofphysicalorbiological
factors.Physicalmethodsconsistinmechanicaldisintegration
ofbacterialcellsandmyceliumhyphae,andwereusedmainly
intheinitialstageofprotoplastsresearch.Thiswasduetolow
productivityandalsobecauseoftheadverseefectonthephysiology
oftheobtainedcells.Biologicalmethodsuseenzymescapableof
decomposingcomponentsofthemicrobialcellwall.Inthecaseof
filamentousfungi,theseareso-calledlyticcomplexes,whichare
amixtureofmanyenzymes.Theseenzymesaremostlyinductive
innatureandcatalysethedecompositionofvariouscompounds
(mainlypolysaccharides)thatapartofthecellwallorthatare
includedincellwall.
Thefollowingcanbeusedtoobtainlyticenzymes:
enzymesofthedigestivejuiceoftheediblesnail
(Helixpomatia),previouslyfedwithbiomassofsuch
microorganismsfromwhichprotoplastsarerequired;
cultureliquidsobtainedfromthecultureofsome
microorganisms-soilbacteria(mainlyActinomycetes
ofStreptomycesandMicromonosporagenera)and
micromycetesstrainsofTrichodermagenus(including,
aboveall,T.virideandT.harzianumspecies).Since,as
previouslyindicated,lyticenzymesaremainlyinductive
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