Production of heterologous polygalacturonase I from Aspergillus kawachii in Saccharomyces cerevisiae in batch and fed-batch cultures.

The pg1 gene from the filamentous fungus Aspergillus kawachii, which codifies for an acid polygalacturonase, was cloned into the pYES2 expression vector, giving rise to the pYES2:pg1ΔI construct. Engineered Saccharomyces cerevisiae, transformed with pYES2:pg1ΔI construct, both expressed and exported an active polygalacturonase with a MW of ~60 kDa and an isoelectric point of 3.7, similar to those reported for the wild-type enzyme. The recombinant enzyme has the ability to hydrolyze polygalacturonic acid at pH 2.5. Heterologous PG1 production was studied under controlled conditions in batch and fed-batch systems. A simultaneous addition of glucose and galactose was found to be the most suitable feeding strategy assayed, resulting in a final PG1 production of 50 U/ml. The production process proposed in this study could be applied for the industrial production of a novel and useful polygalacturonase.

[Prevalence of viral antibodies and syphilis serology in blood donors from a hospital]. / Prevalencia de anticuerpos virales y reaginas luéticas en donadores de sangre de un hospital.

OBJECTIVE: To establish the prevalence of viral antibodies and luetic reagins in blood donors in a Mexican hospital. SETTING: A third level general hospital for government employees located in the city of Morelia, State of Michoacan, Mexico. MATERIAL AND METHODS: Blood samples were collected from 10,077 healthy volunteer donors in a seven year period (01/01/90 to 12/31/96). Serologic tests were performed for HIV antibodies (anti-HIV), HBsAg and RPR. Anti-HCV were tested in 7,256 samples collected from 07/01/92 to 12/31/96. RESULTS: Anti-HIV was found in 19 donors (0.18%), HBsAg in 34 (0.33%), RPR in 12 (0.11%) and anti-HCV in 22 (0.30%). These prevalence rates are in agreement with reports from other Mexican blood banks.