Purification and characterization of an extracellular polygalacturonase from Lactobacillus plantarum strain BA 11

Abstract

Lactobacillus plantarum produced extracellular polygalacturonase in a medium containing 1.5% low methyl‐pectin (w/v) and 0.5% glucose (w/v) as inducers. The enzyme was purified (approximately 70‐fold) by ammonium sulphate fractionation, Sephadex G‐100 gel filtration and DEAE‐cellulose ion exchange chromatography. Two peaks (PG I and PG II) of enzymic activity were obtained from the DEAE‐cellulose column. The molecular mass of PG I was similar to that of PG II (32 000 Da). The Km values of PG I and PG II for sodium polypectate were calculated to be 1.63 mg/ml and 1.78 mg/ml respectively. Their isoelectric points were about pH 5.5. The pH optimum was 4.5, while the optimum temperature was 35°C for both PG I and PG II. The two purified enzymes had similar endo modes of action on polygalacturonic acid, as determined by comparison of viscosity reduction and reducing group release.

Selection criteria for lactic acid bacteria to be used as starter cultures for various food commodities

“…Up till now it is not clear whether strains of LAB are significantly involved in these softening processes, lndeed, the presence of a pectinesterase and an endopolygalacturonase activity was found to be present in a strain of Lb. plantarum [38,39], but to date this has not been confirmed by other researchers.…”

Analysis of Pectin Methyl Esterases

“…In comparison with plants, microbial PMEs often present more acidic pIs, between 3.6 and 6.8 (Rexova-Benkova and Markovic 1976;Markovic et al 1983;Sakellaris and Evangelopoulos 1989;Khanh et al 1991), except for the phytopathogenic enterobacterium Erwinia chrysanthemi, the PME of which presents a pI of 9.64 (Laurent et al 1993). Their Mr ranges from 27800 to 48000; they also differ from plant PMEs in their catalytic properties.…”

Involvement of pectolytic micro‐organisms in coffee fermentation

“…The halo diameters were always largest with E. herbicola than K. pneumoniae , suggesting a stronger enzymatic activity. L. brevis L166 produced a PG activity as earlier identified for Lactobacillus plantarum (Sakellaris et al ., 1988; 1989) and Lactobacillus casei (Karam & Belarbi, 1995). The enzymatic activities were always extracellular except the L. brevis L166 PG associated with the cells.…”

“…These enzymes could not be active at the fermentation pH (5.3–3.5). The maximal activity of L. brevis L166 PG was at pH 4.2 whereas L. plantarum activity was best at pH 4.5 (Sakellaris et al ., 1988; 1989). This PG would be the only enzyme that could be efficient at the fermentation pH although this strain was rarely isolated (Avallone et al ., 2001).…”

“…Inocula of pectolytic strains were prepared for fermentation seeding from 24 h‐old‐cultures in the same broth. Cells were obtained by centrifugation (20 min, 11 500 g ) and washed twice with sodium acetate (0.05 M , pH 4.5) (Sakellaris et al ., 1989). After inoculation, micro‐organisms were numbered on plates incubated during 48 h at 30 °C: lactic microflora on De Man Rogosa and Sharpe agar (MRS) (De Man et al ., 1960), yeast on Yeast Glucose Chloramphenicol agar (YGC) containing 0.25 g L −1 of the antibiotic and aerobic bacteria on Plate Count Agar (PCA).…”