Growth and exopolysaccharide production by Azotobacter vinelandii in media containing phenolic acids

Abstract

Azotobacter vinelandii was cultured in chemically defined, nitrogen‐free media supplemented with either 4‐hydroxyphenylacetic, 4‐hydroxybenzoic or protocatechuic acids at different concentrations. Under these conditions, biomass, exopolysaccharide production and consumption of the carbon sources were investigated. Results obtained throughout this study showed that 4‐hydroxyphenylacetic acid yielded the highest growth levels measured as biomass, and exopolysaccharide production, independently of the concentration of the carbon source tested. 4‐Hydroxybenzoic acid also supported appreciable growth and exopolysaccharide recovery by A. vinelandii. Protocatechuic acid, however, only allowed a very small production of biomass and exopolysaccharide by the strain investigated. Under given conditions, more than 26% of the carbon source supplied was converted to exopolysaccharide in cultures of A. vinelandii.

Production of B-group vitamins by twoAzotobacterstrains with phenolic compounds as sole carbon source under diazotrophic and adiazotrophic conditions

“…The data show a strong toxicity of PA at concentrations of 5 mmol l À1 for both strains, even though PA is the main product resulting for bioconversion of PB prior to follow the b-keto-adipate pathway of degradation in Azotobacter (Hardisson et al 1969). A similar behaviour has been described for a different A. vinelandii strain (Moreno et al 1999) and might be explained by a regulatory activity of the cells to avoid accumulation of PA over the toxicity threshold. In this respect, it is worth noting that strains ATCC 12837 and H23 grew in media amended with 2 mmol l À1 PA to similar or even higher cell numbers than those reached with the other substrates.…”

“…are well known as aromatic catabolizing organisms, able to degrade a wide range of phenolic structures on chemically-de®ned media (Hardisson et al 1969;Chen et al 1993;Abdalla 1994;Moreno et al 1999) and to grow on complex wastes with a high phenolic content (Martõ Ânez-Toledo et al 1995). However, the ability to utilize certain phenolic compounds as sole carbon sources, the concentrations that can be tolerated, and the rates of degratation, vary largely among strains (Tchan and New 1984).…”

“…Phenolic compounds in the soil come mainly from plant litter decomposition or soil contamination by agrochemicals and are toxic for most microorganisms, but a few genera of bacteria and fungi are able to degrade and use them as carbon sources (Hardisson et al 1969). Growth and N 2 -®xation supported by some phenolic monomers, at concentrations well over the range commonly found in natural soils, have been reported for A. vinelandii strains (Peterson and Peterson 1988;Moreno et al 1999).…”

Exploration and characterization of exopolysaccharide-producing bacteria from soil in West Kalimantan for improving sandy soil aggregation

“…Selected bacteria which produceEPS characterized by colonies of bacteria that form thick slime (mucoid) (Tallgren et al 1999) were purified by streaking the four quadrants to obtain single colonies. Selection of potential exopolysaccharide-producing bacteria that form thick slime in MacConkey medium was conducted in two stages: Single stage selection: single colony was grown on MacConkey medium using different carbon sources of sucrose and glucose with concentrations: 1, 2, and 3% (b/v) (Moreno et al 1999;Serrato et al, 2006). Second stage selection: potential exopolysaccharide-producing bacteria in single stage selection were inoculated in medium ATCC no.…”

Karakteristik gugus fungsional eksopolisakarida Burkholderia cenocepacia strain KTG dalam tiga kelas tekstur tanah The characteristic of exopolysaccharide functional group of Burkholderia cenocepacia strain KTG in three soil texture classes

“…Hasil penelitian ini diharapkan dapat digunakan sebagai landasan untuk mengetahui mekanisme pembentukan agregat tanah oleh eksopolisakarida B. cenocepacia strain KTG. (Moreno et al, 1999;Serrato et al, 2006). Perlakuan tersebut dilakukan dengan tiga ulangan.…”