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Marine psychrophile-derived cold-active polygalacturonase: Enhancement of productivity in Thalassospira frigidphilosprofundus S3BA12 by whole cell immobilization

Adapa, Vijayanand, Pulicherla, Krishnakanth, Sambasiva Rao, KRS
Biochemical engineering journal 2019 v.144 pp. 135-147
Thalassospira, aquatic organisms, dissociation, foams, mechanistic models, polygalacturonase, polyurethanes, salinity
The productivity of cold-active polygalacturonase (PGase) in a newly identified marine psychrophile, Thalassospira frigidphilosprofundus S3BA12, was increased multifold by employing high-cell-density (HCD) culturing in a simulation-assisted, custom-designed single-stage-continuous immobilized reactor. The reactor was made “halophilic culturing” ready by using surface altered polyurethane foam (PUF) as a matrix, and it was uniquely packed with layers of “spacers” to increase robustness towards high salinity, prevent salt deposition and dissociation of cells. The basic limitation of low growth of a marine organism was overcome in this study, where HCD resulted in a 4-fold increase of cell mass from 0.84 dcw g/L in submerged culture to 3.22 g/L, which commensurately increased the PGase titre from 21.0 U/ml to 85.25 U/ml. The culture was sustained for 108 h, continuously producing PGase at a rate of 7.87 U/ml hr−1. This could be the highest reported cold-active PGase by any psychrophilic organism reported to date. A mechanistic modelling approach was used to develop a simulation of the process in ChemCAD 5.0, which can be used as a basis for scale-up studies. This study proved statistically that PGase titre is significantly dependent on cell mass using Anderson-Darlington normality tests and established a correlation between PGase and other pectinase subtypes using Pearson’s correlation coefficient analysis.