Title:Optimization of Growth Conditions for Oxalate Decarboxylase Production
from Pseudomonas sp. OXDC12 and in vitro Inhibition of Calcium Oxalate
Crystallization by Oxalate Decarboxylase
Volume: 10
Issue: 2
Author(s): Shruti Gupta and Shamsher S. Kanwar*
Affiliation:
- Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla-171 005, India
Keywords:
Oxalate decarboxylase, kidney stones, pseudomonas, response surface methodology, optimization, calcium oxalate crystallization.
Abstract: Background: Kidney stones have become a common disease worldwide, and their incidence
and recurrence rates have drastically increased over the past few decades. Oxalate decarboxylase
(OxDC) enzyme which catalyzes the disproportionation reaction of oxalate monoanions into
formate and CO2 could exhibit significant potential in the treatment of hyperoxaluria.
Objective: The present work describes isolation and screening of new OxDC producing bacterial
strain from oxalate-rich soils and one-factor-at-a-time (OFAT) and response surface methodology
(RSM) statistical approaches were used to optimize the production media to obtain an improved intracellular
OxDC production.
Methods and Results: An OxDC producing bacterial strain, isolated from spinach soil sample(s),
was identified to be Pseudomonas sp. OXDC12 by 16S rRNA sequencing. The OFAT approach
was used to determine the effect of supplementation of carbon, nitrogen, and other physical conditions
like pH, temperature, etc. on intracellular OxDC production by Pseudomonas sp. OXDC12.
The three factors screened by Plackett Burman design (PBD) were further used by the central composite
design (CCD) approach of RSM to determine their interactive effects on OxDC production.
The anti-urolithiatic activity of the enzyme OxDC was determined by carrying out in vitro calcium
oxalate crystallization in the presence and absence of OxDC. The factorial values selected by 23
CCD for OxDC were temperature 30ºC, manganese ion concentration 5 mmol l-1, and inoculum
size 3.25% (v/v). The highest predicted value of OxDC was 5.7 U ml-1 while the actual value obtained
was 6.7 U ml-1 which was 79.1% and 2.92 fold greater than the initial activity of OxDC produced
by Pseudomonas sp. OXDC12. As depicted by the light micrographs, OxDC displayed a significant
reduction in the crystallization and formation of calcium oxalate stones as compared to the
control under in vitro conditions.
Conclusion: OFAT and RSM statistical optimization approaches led to improved OxDC production
with a final activity of 6.7 U/mL and a 2.92 fold increase in the enzyme activity. The study
suggests that OFAT and RSM optimization approaches significantly enhanced OxDC production
from Pseudomonas sp. OXDC12. The enzyme may serve as a potential therapeutic agent for hyperoxaluria
or kidney stones as it significantly inhibited the formation of calcium oxalate crystals under
in vitro conditions.
