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The accumulation of exopolysaccharides (EPS) produced by microorganisms occurs in the presence of excess substrate and limiting conditions of elements that are essential to growth, such as nitrogen, phosphorus, sulfur, and magnesium. The presence of EPS produced by bacterial cells contributes to slime colonies formation in solid medium and increased viscosity in liquid medium. This paper proposes an alternative method for screening EPS-producing lactic acid bacteria using solid medium-containing discs of filter paper that are saturated with active cultures. The screening was carried out under different culture conditions varying the type of sugar, pH, and temperature. EPS production was visualized by the presence of mucoid colonies on the discs, which was confirmed by the formation of a precipitate when part of this colony was mixed with absolute alcohol. The established conditions for obtaining a high number of isolates producing EPS were 10% sucrose, pH 7.5 and 28 ºC. This method proved to be effective and economical because several strains could be tested on the same plate, with immediate confirmation.

The enzyme pectin methylesterase (PME) from orange was extracted and partially purified by filtration on Sephadex G‐100. The extraction buffer for orange PME was borate–acetate containing 0.4 M NaCl. Orange PME showed optimum pH at 8.0 and optimum temperature at 50C. The PME enzyme was completely inactivated after 1 min of incubation at 90C. The specific activity increased in the presence of 0.15 M NaCl or 0.025 M Na 2 SO 4 , 0.10 M KCl, 0.025 M K 2 SO 4 , 0.05 and 0.1 M NH 4 Cl. Lithium chloride and Li 2 SO 4 inhibited the enzymatic activity at all concentrations studied. The Km and Vmaxvalue of PME were 0.36 mg/mL and 5.26 µmol/mL‐mg protein, respectively.