Whole-cell biocatalysis in organic media

Bacterial polyesters have been found to have useful properties for applications as thermoplastics, elastomers, and adhesives and are biodegradable and biocompatible. Poly(3-hydroxyalkanoates) (PHAs) and poly(β-malate) are the most representative polyesters synthesized b microorganisms. PHAs containing a wide variety of repeating units can be produced by bacteria, including those containing many types of pendant functional groups which can be synthesized by microorganisms that are grown on unnatural organic substrates. Poly(β-malate) is of interest primarily for medical applications, especially for drug delivery systems. In this chapter, the bacterial production and properties of poly(3-hydroxyalkanoates) and poly(β-malate) are described with emphasis on the former.

Polyesters from microorganisms.

A protocol has been developed for the rapid determination of complete elimination characteristics of target pollutants in waste air biofilters. The protocol involves the determination of two pollutant concentration profiles along the height of a three-segment biofilter under carefully chosen conditions. The combination of the data results in 12 points on the elimination capacity vs load curve which is sufficient to fully characterize a system. The protocol conditions were chosen to enable characterization of biofiltration systems with VOC elimination capacities ranging from 20 to 120 g m-3 h-1. The protocol was then applied to 18 different VOCs, and the results compared well with previously published data, when available. Maximum removal performance of classes of compounds in the biofilter followed the sequence alcohols > esters > ketones > aromatics > alkanes. An attempt was made to correlate the pollutant elimination with Henry's coefficient, and the octanol/water partition coefficient and trends were o...

Development and Validation of a Simple Protocol To Rapidly Determine the Performance of Biofilters for VOC Treatment

Ionic liquids are compounds that composed only of ions and are liquid at room temperature. Thus, it is normally named room temperature ionic liquid (RTIL). In this study, the application of RTILs to the extractive fermentation of biomaterials was investigated as a substitute of organic solvents. The relative toxicity of the RTILs on the growth ofE. coli was tested. The inhibition of cell growth in the presence of various ionic liquids was measured using solid and liquid culture, and EC50 of each RTILs was calculated. The number of viable and total cells was measured by the number of colonies and optical density, respectively. Effective concentrations of toxicity (EC50) in these tested systems were similar with conventional solvents, such as acetone, acetonitrile, and ethanol. The viability ofE. coli was affected by the polarity and ionic properties of ionic liquids. The resistance of the microorganisms against ionic liquids was different with the cations and anions composing ionic liquids. No general influence of the anionic compound of the ionic liquids was found on toxicity comparing with distinctive influence of cationic moiety.

/pdf/influence-of-ionic-liquids-on-the-growth-ofescherichia-coli-495qchyt6z.pdf

Influence of ionic liquids on the growth ofEscherichia coli

Recombinant strains of Pseudomonas putida KT2440 carrying genetic expression cassettes with xylene oxygenase- and styrene monooxygenase-encoding genes on their chromosomes could be induced in shaking-flask experiments to specific activities that rivaled those of multicopy-plasmid-based Escherichia coli recombinants. Such strains maintained the introduced styrene oxidation activity in continuous two-liquid-phase cultures for at least 100 generations, although at a lower level than in the shaking-flask experiments. The data suggest that placement of target genes on the chromosome might be a suitable route for the construction of segregationally stable and highly active whole-cell biocatalysts.

https://aem.asm.org/content/aem/65/12/5619.full.pdf

Aravalli N. Rajagopal

Papers

Growth of Gram-negative bacteria in the presence of organic solvents