Effect of medium composition and kinetic studies on extracellular and intracellular production of L-asparaginase from Pectobacterium carotovorum

Interferences that impact measuring optimal L-asparaginase activity and consequent errors interpreting these data

L-asparaginase is an enzyme produced by microorganisms, plants, and animals, which is used clinically for the treatment for acute lymphoblastic leukemia (ALL) and, in the food industry, to control acrylamide formation in baked foods. The purpose of this review was to evaluate the available literature regarding microbial sources of L-asparaginase, culture media used to achieve maximum enzyme expression in microbial fermentations, and assay methods employed to assess L-asparaginase activity. Studies were gathered by searching PubMed, and Web of Science databases before January 22, 2018, with no time restrictions. The articles were evaluated according to the source of L-asparaginase being studied, the nitrogen source in the culture medium, the type of sample, and the method employed to evaluate L-asparaginase activity. Bacterial L-asparaginase appeared to be the most commonly studied source of the enzyme and, most often, the enzyme activity was assayed from crude protein extracts using the Nessler method, which is an indirect measurement of asparaginase activity that determines the concentration of ammonia generated after the action of the enzyme on the substrate, L-asparagine. However, ammonia is also generated throughout microbial fermentations and this endogenous ammonia will also reduce the Nessler reagent if crude microbial extracts are used to determine total L-asparaginase activity. We suggest that current estimates of L-asparaginase activity reported in the literature may be overestimated when Nessler reagent is used, since we were unable to find a single study that made reference to the possible inference of fermentation derived ammonia.

Single step biotransformation of corn oil phytosterols to boldenone by a newly isolated Pseudomonas aeruginosa

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Biotransformation of crude corn oil phytosterols to 4-androstene-3, 17-dione, testosterone and boldenone.

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Four strains of Pseudomonas aeruginosa and one of Alcaligenes aquatilis were isolated, identified and used in biotransformation process.

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Determination of crude corn oil total sterols and phytosterols profile.

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Optimization of boldenone production by Placket-Burman design and box-Behnken design.

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Accumulation of boldenone (BOL) as the major product of the biotransformation process, and the rare reports about optimization of its production from phytosterols, make it a selected promising candidate for further optimization. The production of BOL in single step microbial biotransformation from corn oil phytosterols by P. aeruginosa was not previously reported.

A new potent Pseudomonas aeruginosa isolate capable for biotransformation of corn oil phytosterol (PS) to 4-androstene-3, 17-dione (AD), testosterone (T) and boldenone (BOL) was identified by phenotypic analysis and 16S rRNA gene sequencing. Sequential statistical strategy was used to optimize the biotransformation process mainly concerning BOL using Factorial design and response surface methodology (RSM). The production of BOL in single step microbial biotransformation from corn oil phytosterols by P. aeruginosa was not previously reported. Results showed that the pH concentration of the medium, (NH₄)₂SO₄ and KH₂PO₄ were the most significant factors affecting BOL production. By analyzing the statistical model of three-dimensional surface plot, BOL production increased from 36.8% to 42.4% after the first step of optimization, and the overall biotransformation increased to 51.9%. After applying the second step of the sequential statistical strategy BOL production increased to 53.6%, and the overall biotransformation increased to 91.9% using the following optimized medium composition (g/l distilled water) (NH₄)₂SO₄, 2; KH₂PO₄, 4; Na₂HPO₄. 1; MgSO₄·7H₂O, 0.3; NaCl, 0.1; CaCl₂·2H₂O, 0.1; FeSO₄·7H₂O, 0.001; ammonium acetate 0.001; Tween 80, 0.05%; corn oil 0.5%; 8-hydroxyquinoline 0.016; pH 8; 200 rpm agitation speed and incubation time 36 h at 30 °C. Validation experiments proved the adequacy and accuracy of model, and the results showed the predicted value agreed well with the experimental values.

Screening and characterization of extracelluar L-asparaginase producing Bacillus subtilis strain hswx88, isolated from Taptapani hotspring of Odisha, India

OBJECTIVE

To screen and isolate an eco-friendly, a thermophilic and potent L-asparaginase producing bacterium, with novel immunological properties that may obviates hypersensitivity reactions.

METHODS

In the present study bacterial strain isolated for extracellular L-asparaginase production from hotspring, identified by morphological, biochemical and physiological tests followed by 16S rDNA technology and the L-asparaginase production ability was tested by both semi quantitative and quantitative enzymatic assay.

RESULTS

The bacterial strain was identified as Bacillus subtilis strain hswx88 (GenBank Accession Number: JQ237656.1). The extracellular enzyme yielding capacity isolate Bacillus subtilis strain hswx88 (23.8 IU/mL) was found to be 1.7 and 14.5 times higher than the reference organism Pectobacterium carotovorum MTCC 1428 (14.2 IU/mL) and Bacillus sp. BCCS 034 (1.64 IU/mL).

CONCLUSION

The isolate is eco-friendly and useful to produce bulk quantity of extracellular, thermophilic L-asparaginase for the treatment of various tumor cases and for preparation of acrylamide free fry food preparation.