Effect of Stirring on Growth an Phosphopolysaccharide Production by Lactobacillus helveticus ATCC 15807 in Milk

TORINO, MARÍA INÉS; MOZZI, FERNANDA; SESMA, FERNANDO; FONT DE VALDEZ, GRACIELA

MILCHWISSENSCHAFT-MILK SCIENCE INTERNATIONAL

A V A AGRARVERLAG

Año: 2000 vol. 55 p. 204 - 206

0026-3788

The exopolysaccharide production by Lactobacillus helveticus ATCC 15807 in milk fermentations was studied in a 60 h batch culture. Maximum yields of exopolysaccharide were detected at the beginning of stationary phase (399.4 mg/l) in stirred cultures and at a late exponential growth phase (318 mg/l) in non-stirred cultures. The slime material contained phosphorus and carbohydrates. Glucose and galactose were the main monomers found. The phosphorus:carbohydrate and glucose:galactose ratio was dependent on the fermentation time as well as on the culture conditions. The molecular weight was estimated to be up to 106 in both assays. The viscosity of the cultures was not related to the amount of exopolysaccharide produced since no ropiness was developed by stirred cultures. Lactic acid was produced throughout fermentation despite the reduction in cell viability, remaining about 20% lactose in the culture medium after 60 h of incubation.