An Eco-Friendly and Sustainable Process for Enzymatic Hydrolysis of Penicillin G in Cloud Point System

Clouding behaviour in surfactant systems

A study on the phenomenon of clouding and the applications of cloud point technology has been thoroughly discussed. The phase behaviour of clouding and various methods adopted for the determination of cloud point of various surfactant systems have been elucidated. The systems containing anionic, cationic, nonionic surfactants as well as microemulsions have been reviewed with respect to their clouding phenomena and the effects of structural variation in the surfactant systems have been incorporated. Additives of various natures control the clouding of surfactants. Electrolytes, nonelectrolytes, organic substances as well as ionic surfactants, when present in the surfactant solutions, play a major role in the clouding phenomena. The review includes the morphological study of clouds and their applications in the extraction of trace inorganic, organic materials as well as pesticides and protein substrates from different sources.

Enhancement of substrate concentration in microbial stereoinversion through one-pot oxidation and reduction by aqueous two-phase system

An extractive biocatalytic method of aqueous two-phase system was employed for stereoinversing (R)-1-phenyl-1,2-ethanediol into (S)-1-phenyl-1,2-ethanediol by Candida parapsilosis CCTCC M203011. It was observed that substrate and product inhibitions in microbial stereoinversion through one-pot oxidation and reduction were removed efficiently by extractive biocatalysis in aqueous two-phase system with PEG 4000/phosphate potassium system, and that the substrate concentration was enhanced from 15 to 30 g/L with product optical purity of 99.02% e.e. and yield of 90% after 60 h. Simultaneously, it was observed that change in cell morphology impedes the further enhancement of substrate concentration in this system but can be reversibly changed after stereoinversion or cultivation in systems without PEG.

6-aminopenicillanic acid production by intact cells of E. coli containing penicillin G acylase (PGA)

The aim of present study was to optimize conditions for conversion of penicillin G into 6-APA using intact crude cells of locally collected PGA producing bacterial strains as biocatalyst. Corn steep liquor medium supplemented with phenylacetic acid was used for PGA production. For enzymatic conversion of penicillin G into 6-APA by PGA impregnated bacterial cells, a maximum reaction time of 4 h was found adequate. The procedure for extraction and crystallization of 6-APA from the enzyme reaction mixture was standardized. Isolation process was carried out under controlled pH conditions and 6-APA crystals were recovered from the reaction mixture via filtration, concentration and drying. The maximum PGA activity was observed in Escherichia coli strain BDCS-N-FMu12 (6.4 mg 6-APA h(-1) mg(-1) wet cells) whereas Bacillus megaterium (ATCC 14945 used as check) exhibited only 2.4 mg 6-APA h(-1) mg(-1) wet cells. The overall yield of 6-APA crystals obtained after enzymatic conversion of penicillin G ranged between 37-55 and 47-68% in foreign and local strains, respectively. BDCS-N-FMu12 was identified as the best PGA producer with 68% 6-APA conversion whereas ATCC 14945 showed the lowest conversion (37%). The recovery of 6-APA (68%) obtained by using crude intact cells as cheap biocatalyst appeared promising. The process of enzyme fermentation and 6-APA crystallization optimized during this study seems cost-effective and environment-friendly. However, further studies are required to scale up the 6-APA biosynthesis reaction for achieving 80-90% conversion of penicillin G into 6-APA by PGA hyper-producing locally collected strains of E. coli.

The potential of cloud point system as a novel two-phase partitioning system for biotransformation

Although the extractive biotransformation in two-phase partitioning systems have been studied extensively, such as the water-organic solvent two-phase system, the aqueous two-phase system, the reverse micelle system, and the room temperature ionic liquid, etc., this has not yet resulted in a widespread industrial application. Based on the discussion of the main obstacles, an exploitation of a cloud point system, which has already been applied in a separation field known as a cloud point extraction, as a novel two-phase partitioning system for biotransformation, is reviewed by analysis of some topical examples. At the end of the review, the process control and downstream processing in the application of the novel two-phase partitioning system for biotransformation are also briefly discussed.