Proto pla st s f r om one species of br ow n alga Sargassum f usif orme ( Harv. ) Setchell had been obta ined w ith the applicat ion o f wa ll degrading enzymes. The inte rnal facto rs and external co ndit ions o f the iso latio n o f proto pla sts , such a s kinds and co nce nt rat io ns of o smo regulate d re agent, kinds and combinat ions of enzymes, isola ted tempe rature a nd pH, t ime o f ma ter ial collect ions and part of thallus, are def inited now . Hav ing been cultur ed for 3 da ys, some pr otoplast s regenerated cel-l w alls and div ided into tw o cel ls. Six-cell cal lus-like cel-l ma ss wa s also obtained af te r being cultur ed for 6 day s. The se re sult s are g oo d basis f or further culture in large scale. The applica tio n o f marine bacteria on isolat ing vegetat ive cel ls o f these alg a is reported in this pa per.