Effects of aromatic compounds on the production of bacterial nanocellulose by Gluconacetobacter xylinus

Abstract

BackgroundBacterial cellulose (BC) is a polymeric nanostructured fibrillar network produced by certain microorganisms, principally Gluconacetobacter xylinus. BC has a great potential of application in many fields. Lignocellulosic biomass has been investigated as a cost-effective feedstock for BC production through pretreatment and hydrolysis. It is well known that detoxification of lignocellulosic hydrolysates may be required to achieve efficient production of BC. Recent results suggest that phenolic compounds contribute to the inhibition of G. xylinus. However, very little is known about the effect on G. xylinus of specific lignocellulose-derived inhibitors. In this study, the inhibitory effects of four phenolic model compounds (coniferyl aldehyde, ferulic acid, vanillin and 4-hydroxybenzoic acid) on the growth of G. xylinus, the pH of the culture medium, and the production of BC were investigated in detail. The stability of the phenolics in the bacterial cultures was investigated and the main bioconversion products were identified and quantified.ResultsConiferyl aldehyde was the most potent inhibitor, followed by vanillin, ferulic acid, and 4-hydroxybenzoic acid. There was no BC produced even with coniferyl aldehyde concentrations as low as 2 mM. Vanillin displayed a negative effect on the bacteria and when the vanillin concentration was raised to 2.5 mM the volumetric yield of BC decreased to ~40% of that obtained in control medium without inhibitors. The phenolic acids, ferulic acid and 4-hydroxybenzoic acid, showed almost no toxic effects when less than 2.5 mM. The bacterial cultures oxidized coniferyl aldehyde to ferulic acid with a yield of up to 81%. Vanillin was reduced to vanillyl alcohol with a yield of up to 80%.ConclusionsThis is the first investigation of the effect of specific phenolics on the production of BC by G. xylinus, and is also the first demonstration of the ability of G. xylinus to convert phenolic compounds. This study gives a better understanding of how phenolic compounds and G. xylinus cultures are affected by each other. Investigations in this area are useful for elucidating the mechanism behind inhibition of G. xylinus in lignocellulosic hydrolysates and for understanding how production of BC using lignocellulosic feedstocks can be performed in an efficient way.

Oxygen radical based on non-thermal atmospheric pressure plasma alleviates lignin-derived phenolic toxicity in yeast

“…S. cerevisiae is a traditionally competitive cell factory used for bioethanol production due to its superior tolerance to ethanol and low pH, as well as its ease of genetic manipulation [42]. To overcome vanillin toxicity as a barrier to reduced bioethanol-production costs, vanillin-tolerant strains have been screened and engineered [38,[43][44][45]; however, these strains have not fully resolved the problems of toxicity associated with lignin-derived phenolics, which have been documented in other fermentable microorganisms (i.e., ethanol fermentation by Thermoanaerobacter mathranii, butanol fermentation by Clostridium beijerinckii and Clostridium acetobutylicum, butyric acid fermentation by Clostridium tyrobutyricum, hydrogen fermentation by Thermoanaerobacter thermosaccharolyticum, bacterial nanocellulose [46][47][48][49][50][51][52]. Therefore, the presence of lignin-derived phenolics remains a problem in biorefining processes using lignocellulosic biomass.…”

Bacterial nanocellulose production and application: a 10-year overview

“…For this reason, there are currently several methodologies for large-scale production of BNC. Researchers have focused on improving the efficiency of the production process, resulting in satisfactory yields that are compatible with the demand for this type of cellulose Zhang et al 2014;Cakar et al 2014;Li et al 2015).…”

Surface Interactions between Bacterial Nanocellulose and B-Complex Vitamins

“…Of all these industries, food and drug delivery systems have received particular attention in recent years [ 15 , 20 ]. In the case of food, BNC is edible, and it has been reported with an ability to be utilized as a multifunctional food ingredient, rheological enhancer [ 15 , 21 ], and a low-calorie food additive. Moreover, BNC has also been used in low cholesterol products [ 18 ], for thickening [ 11 ], and as a gelling and stabilizer agent [ 18 , 21 , 22 ].…”