Qian Liu, Lili Lu, Min Xiao*

Bioresource Technol, 2012, 123: 144–149.

ABSTRACT

An a-L-rhamnosidase gene (rhaL1) containing an open reading frame of 2046-bp encoding a 681-amino acid protein (RhaL1) was cloned from Alternaria sp. L1 for naringin hydrolysis on the cell surface of Saccharomyces cerevisiae EBY-100. RhaL1 anchored to the yeast cell surface showed maximum enzyme activity at pH 6.0–6.5 and 70℃ and was stable at pH 2.5–12.0 below 60 ℃. When the yeast cells were employed to hydrolyze naringin in grapefruit juice, about 85% naringin was hydrolyzed at 60℃ in 10 min. The yeast cells were harvested and recycled for the next batch. The hydrolysis rate of the naringin was maintained at over 80% for 10 batches. These results demonstrate the stability of the RhaL1-expressing yeast cells and effective in hydrolysis of naringin in juice. Thus, the system could have promise for industrial bitterness reduction.