The effect of phytohormones on the growth, cellulose production and pellicle properties of Gluconacetobacter xylinus ATCC 53582

Abstract

Gluconacetobacter xylinus is a plant-associated bacterium best studied for its cellulose production. Bacterial cellulose is important in facilitating plant-microbe interactions but little is known about the effect that exogenous phytohormones have on bacterial cellulose synthesis or the growth of G. xylinus. We characterized the growth, development and effect on pellicle characteristics caused by exogenous indole-3-acetic acid (IAA), gibberellic acid (GA), abscisic acid (ABA) and zeatin (Z) over a range of concentrations (1 nM to 100 μM). These phytohormones are plant growth regulators known to be involved plant development including fruit ripening and stress tolerance. Each of these hormones stimulated G. xylinus growth and influenced its pellicle characteristics. Exogenous IAA had the greatest effect on G. xylinus pellicles. Growth in IAA produced thin pellicles with very little cellulose. In general, pellicle wet weight was inversely proportional to the bacterial cellulose yield when cultures were grown in the presence of ABA, suggesting ABA influenced pellicle density and hydration. The crystallinity index, CI (IR) of cellulose produced in the presence of each phytohormone over a variety of concentrations was determined by Fourier transform infrared spectroscopy. The observed effect on cellulose crystallinity was concentration and hormone dependent. GA caused the greatest alterations in crystallinity with the highest CI (IR)=0.94 at 1 μM and the lowest CI (IR)=0.47 at 500 nM. Endogenous production of hormones by G. xylinus was investigated by high performance liquid chromatography of extracts prepared from both cell pellets and culture supernatants. We found G. xylinus synthesized GA, ABA and Z but did not produce IAA.

Establishing a Role for Bacterial Cellulose in Environmental Interactions: Lessons Learned from Diverse Biofilm-Producing Proteobacteria

“…The fruit fly, Drosophila , preferentially deposits bacteria on the wounds of fruit where nutrients are most plentiful ( Janisiewicz et al, 1999 ). The pH of these wounds is around 3.5 ( Janisiewicz et al, 1999 ) which is similar to the pH of K. xylinus cultures during exponential growth ( Qureshi et al, 2013 ). Bacterial growth within fruit wounds has been observed for a saprophytic strain of Pseudomonas syringae ( Janisiewicz and Marchi, 1992 ), another plant-associated BC producer that resides in the phyllosphere ( Arrebola et al, 2015 ).…”

“…Therefore, AsA acts as a signaling molecule in nature, informing K. xylinus that ripening has commenced, and that nutrients are available for BC production. It should be noted that cell growth was not measured in these studies so it is not known whether the positive effect exerted by AsA on BC production was a direct or an indirect effect of increased growth, as observed for the phytohormones ABA, zeatin, and GA 3 ( Qureshi et al, 2013 ).…”

“…Genes for the biosynthesis of IAA, zeatin-riboside and trans -zeatin are found on the T-DNA region of the tumor-inducing plasmid ( Akiyoshi et al, 1984 ; Thomashow et al, 1984 ). Unlike the rhizosphere bacterium G. diazotrophicus ( Lee and Kennedy, 2000 ), the closely related carposphere bacterium K. xylinus , does not produce endogenous IAA ( Qureshi et al, 2013 ), as it would be counter-productive for its survival; IAA inhibits fruit ripening ( Davies et al, 1997 ; Aharoni et al, 2002 ).…”

Optimization of biomass production of Acetobacter pasteurianus KU710511 as a potential starter for fruit vinegar production

“…Further studies aimed at the optimization of the production of this substance could be considered. Therefore, this phenomenon represents a disadvantage for the use of this bacterium for industrial production of vinegar; it is, however, more suited to be involved in industrial production of cellulose (Fu et al, 2014;Jozala et al, 2015;Qureshi et al, 2013). The GenBank accession numbers for the 16s rRNA sequences of the two selected bacteria, CV01 and AF01, isolated from cactus and apple fruits are KU710511 and KU710512, respectively.…”

Acetic acid bacteria: features and impact in bio-applications

“…A paper reviews the effect of plant phytohormones on the growth and structural features of cellulose, showing that these plant regulators stimulate G. xylinus growth and influence its pellicle characteristics. 6 Among new bioprocesses aimed to sustainable productions, the stabilization of cheese whey, an important source of environmental pollution, is also covered through the development of a stable nutrient recycling system as an ingredient in dairy cattle diet. 7 Last but not least, the maintenance of authentical strains over the preservation time is a priority for the exploitation of acetic acid bacteria as a microbial cell factory.…”