Advances in the Production of Sustainable Bacterial Nanocellulose from Banana Leaves

Abstract

Interest in bacterial nanocellulose (BNC) has grown due to its purity, mechanical properties, and biological compatibility. To address the need for alternative carbon sources in the industrial production of BNC, this study focuses on banana leaves, discarded during harvesting, as a valuable source. Banana midrib juice, rich in nutrients and reducing sugars, is identified as a potential carbon source. An optimal culture medium was designed using a simplex-centroid mixing design and evaluated in a 10 L bioreactor. Techniques such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA) were used to characterize the structural, thermal, and morphological properties of BNC. Banana midrib juice exhibited specific properties, such as pH (5.64), reducing sugars (15.97 g/L), Trolox (45.07 µM), °Brix (4.00), and antioxidant activity (71% DPPH). The model achieved a 99.97% R-adjusted yield of 6.82 g BNC/L. Physicochemical analyses revealed distinctive attributes associated with BNC. This approach optimizes BNC production and emphasizes the banana midrib as a circular solution for BNC production, promoting sustainability in banana farming and contributing to the sustainable development goals.

Keywords: bacterial nanocellulose; banana leaves; biomass; biopolymer; circular bioeconomy; fermentation; optimization; simplex-centroid design; sustainability; yield.

Figure 1

Different approaches for obtaining bacterial cellulose using different carbon sources. (A) Residual biomass rich in sugary juices, which requires minimal physical treatments to extract its sugars, which are then used as a carbon source. (B) Residual biomass containing sugars requires physical, chemical, or biological pre-treatment to extract the sugars. These sugars are then used as a carbon source in fermentation processes. (C) Kombucha tea production uses conventional sugar (sucrose). (D) The carbon source in Hestrin-Schramm (HS) medium is reagent-grade glucose.

Figure 2

Mixing contour plot showing the effect of the variables. Colour coding makes it possible to distinguish the different yield levels of bacterial nanocellulose production: reddish tones indicate lower yields and yellow tones indicate higher yields.

Figure 3

Kinetic analysis of bacterial nanocellulose production: pH and turbidity variations in the culture medium.

Figure 4

SEM images of the bacterial nanocellulose membranes: (A) Obtained in the HS control medium. (B) Obtained in the medium optimized by simplex-centroid design (SCD). Panels (C1,C2) present plots of diameter distribution and standard distribution for HS-BNC and SCD-BNC, respectively.

Figure 5

Characterization of bacterial nanocellulose: Fourier transform infrared spectroscopy spectra. The red line represents the BNC spectrum obtained in the HS control medium, whereas the blue line represents the BNC spectrum obtained in the SCD-optimized medium.

Figure 6

(A) Thermogravimetric analysis curve and (B) derivative thermogravimetry curve. The red line represents the BNC spectrum obtained in the HS control medium, while the blue line represents the BNC spectrum obtained in the SCD-optimized medium.

Figure 7

X-ray diffractogram of bacterial nanocellulose in the optimized medium from banana mid-rib juice, SCD-BNC (blue line), and bacterial nanocellulose in the HS medium, BNC (red line).