Research note: Effect of dissolved oxygen level on lactase production by Kluyveromyces fragilis

✍ Scribed by Sonia Barberis; J. Carlos Gentina

• Publisher: Wiley (John Wiley & Sons)
• Year: 1998
• Tongue: English
• Weight: 188 KB
• Volume: 73
• Category: Article
• ISSN: 0268-2575
• DOI: 10.1002/(sici)1097-4660(199809)73:1<71::aid-jctb924>3.0.co;2-d

✦ Synopsis

The inÑuence of dissolved oxygen (% DO) on lactase production by Kluyveromyces fragilis (NRRL-Y-1109) in chemostat culture using a deÐned medium was studied. The aim was to determine conditions for both high speciÐc enzyme activity and high volumetric enzyme productivity. SigniÐcant di †erences in the speciÐc enzyme activity and speciÐc and volumetric enzyme productivity were found at the corresponding steady states when the DO was varied between 0 and 90%. Maximum lactase production was attained at 10% DO. Under this condition the best results were an enzyme activity of 5910 IU g~1, speciÐc production rate of 1810 IU g~1 h~1 and volumetric production rate of 1530 IU dm~3 h~1. This seem to be due to the fact that at low aeration conditions the yeast metabolism is more reductive and as a consequence it veriÐes both higher speciÐc lactose consumption rate and higher enzyme expression than in full aeration conditions. The results of this investigation are also compared with those of other studies of lactase production by Kluyveromyces sp.