London: The presence of added sugar in dairy products has always led the health conscious consumers to avoid them. But a team of Danish researchers has made it possible to manipulate the metabolic properties of yogurt-producing bacteria to sweeten the yogurt naturally, while reducing sugar in the final product. Also, using microbiological methods the researchers have almost eliminated lactose, so that those with lactose intolerance can enjoy the yogurt. "The goal was to engineer the yogurt bacteria not to consume glucose, a fermentation product that is a particularly sweet form of sugar," said Eric Johansen, one of the researchers who is associate vice president at Chr. Hansen Holding A/S - a global bioscience company in Denmark. The findings are detailed in the journal Applied and Environmental Microbiology. The team engineered the bacteria not to consume glucose, a particularly sweet product of yogurt's fermentation. Yogurt contains live cultures of bacteria known as streptococcus thermophiles and the bulgaricus subspecies of Lactobacillus delbrueckii. When grown in milk, these two strains normally break down the lactose into two sugar components glucose and galactose, which is less sweet than glucose. Then, the bacterium consumes the glucose and makes more galactose. The microbial tweak eliminates lactose, so those intolerant to the milk sugar can eat the yogurt. "We wanted to change them so that they would eat the galactose and spit out the glucose," said Johansen. The yogurt in the newly modified bacteria make has almost no lactose, very little galactose, and is high in glucose. This natural sugar makes it sweet, and when the yogurt was presented to a taste panel with varying amounts of sucrose added, the team found that they could maintain the panel's desired sweetness with 20 percent less added sucrose than usual. "We reasoned that since glucose is considerably sweeter than lactose or galactose, bacteria that release glucose into the product could allow for a reduction in added sugar while maintaining the desired sweetness in the yogurt," Johansen concluded.