Production of green biocellulose nanofibers by Gluconacetobacter xylinus through utilizing the renewable resources of agriculture residues

Abstract

The present study demonstrates the ability to produce green biocellulose nanofibers using the renewable resources of agriculture residues. Locally grown wheat straws (WS) were hydrolyzed under different conditions. Their hydrolysates were utilized to produce the nanofibers in separate hydrolysis fermentation process by Gluconacetobacter xylinus strain bacterium. Highest biocellulose production of ~10.6 g/L was achieved with samples that were enzymatically hydrolyzed. Moreover, acidic hydrolyzed WS produced up to 9.7 g/L, with total sugar concentrations in culture media of 43 g/L. Generally, enzymatic hydrolysis of WS resulted in more total sugar concentration than the acidic hydrolysis (i.e., 52.12 g/L), while water hydrolysis produced the least. This can be related to utilizing Xylanase in addition to Cellulase and Beta-glucosidase that helps to hydrolyse WS dry basis of cellulose and hemicelluloses. Sugar mixtures produced under all hydrolysis conditions were mainly composed of glucose and xylose with average percentages of 56 and 28 %, respectively. Acidic hydrolysis at higher acid concentration, as well as soaking WS in the acidic solution for longer time, improved the total sugar concentration in the culture media by 18 %. Conducting thermal treatment at more intense conditions of higher temperature or heating time improved the total sugar produced with acidic hydrolysis. These conditions, however, resulted in further production of furfural, which considerably affected bacterial cells proliferation. This resulted in lowest sugar consumption in the range of 62-64 % that affected final BC production.

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

“…In recent years, renewable biomass, such as lignocellulosic resources, has been most studied as potential feedstock. Biomass resources that have been investigated include konjak glucomannan [8], rice bark [9], wheat straw [10-12], cotton-based waste textiles [13,14], waste fiber sludge [15] and spruce [16]. The biomass is typically hydrolyzed enzymatically, since this approach gives high sugar yields.…”

Synthesis and characterization of cellulose nanowhisker‐reinforced‐poly(ε‐caprolactone) scaffold for tissue‐engineering applications

“…BC‐producing strain ( G. xylinus) was activated according to ATCC guidelines. BC nanofibers were produced as fermentation product from fructose as C‐source and corn steep liquor as N‐source . BC cellulose was further purified by boiling the pellicles in 0.2 M NaOH solution for 30 min, followed by several rinses with distilled water until a neutral pH was attained.…”

Response to “Comment on ‘Novel Biodegradable Polyurethanes Reinforced with Green Nanofibers for Applications in Tissue Engineering. Synthesis and Characterization’ ” by Swapnil Fegade

“…1) The authors of the article have clearly highlighted the green production process in their earlier articles that were cited in their article. [2] Production of BCNF as described therein was also described as being a green process by other researchers. [3] 2) The letter claims that almost all cellulose fibers are derived from natural (renewable) resources, which makes BCNF not a novel material.…”

“…The letter also does not review the characteristics of the bacterial cellulose nanofibers for being novel environmentally‐friendly, biocompatible, and biodegradable biomaterials. Main points that should be considered when discussing the greenness of BCNFs are: The authors of the article have clearly highlighted the green production process in their earlier articles that were cited in their article . Production of BCNF as described therein was also described as being a green process by other researchers …”

“…The low concentrations of such chemicals, and their not being a major part of the synthesis process, does not impact the greenness of the process. [2] 4) There have been several published articles earlier where the term "green nanofibers" was used to describe different nanofibers in spite of their nano-size. [4][5][6][7] 5) It is also worth noting that the article did not focus on how green the nanofibers are.…”