Biological Characterization and Instrumental Analytical Comparison of Two Biorefining Pretreatments for Water Hyacinth (Eichhornia crassipes) Biomass Hydrolysis

Abstract

Water hyacinth is a rapidly growing troublesome aquatic weed plant, which causes eutrophication in water bodies and irreversible damage to the ecological system. In this work, we have investigated the water hyacinth biomass (WHB) hydrolysis efficacy of dilute alkaline (DA) pretreatment followed by biological pretreatment with white-rot fungus Alternaria alternata strain AKJK-2. The effectiveness of the dilute alkaline (DA) and biological pretreatment process on WHB was confirmed by using X-ray Diffraction (XRD) and Fourier Transform Infrared Spectrophotometer (FTIR), and was further visualized by Scanning Electron Microscope (SEM) and Confocal Laser Scanning Microscopy (CLSM). XRD spectra showed the increase in the crystallinity of pretreated samples, attributed to the elimination of amorphous components as lignin and hemicellulose. FTIR peak analysis of pre-treated WHB showed substantial changes in the absorption of cellulose functional groups and the elimination of lignin signals. Scanning electron microscopy (SEM) images showed firm, compact, highly ordered, and rigid fibril structures without degradation in the untreated WHB sample, while the pretreated samples exhibited loose, dispersed, and distorted structures. XRD indices (Segal, Landis, and Faneite), and FTIR indices [Hydrogen bond intensity (HBI); Total crystallinity index (TCI); and Lateral order crystallinity (LOI)] results were similar to the aforementioned results, and also showed an increase in the crystallinity both in alkaline and biological pretreatments. Alkaline pretreated WHB, with these indices, also showed the highest crystallinity and a crystalline allomorphs mixture of cellulose I (native) and cellulose II. These results were further validated by the CLSM, wherein fluorescent signals were lost after the pretreatment of WHB over control. Overall, these findings showed the significant potential of integrated assessment tools with chemical and biological pretreatment for large-scale utilization and bioconversion of this potential aquatic weed for bioenergy production.

Identification of Cellulose-Degrading Bacteria and Assessment of Their Potential Value for the Production of Bioethanol from Coconut Oil Cake Waste

“…These results are consistent with those of Liu et al [ 48 ], who used SEM and observed that the outer surface of treated corn cobs became cracked and somewhat wrinkled due to the breakage of the complex lignocellulosic structure of the biomass when treated by fungi. Singh et al [ 49 ] also found that microbial attack causes changes in the original fiber at the molecular level and determined that the formation of pores and cracks during degradation is correlated with the amount of reducing sugar produced.…”

Application of ligninolytic bacteria to the enhancement of lignocellulose breakdown and methane production from oil palm empty fruit bunches (OPEFB)

“…These is proved by sugar production which was higher on the pre-treated samples compare to non-treated samples. Singh et al (2021) stated that the structure of lignocellulosic biomass through biological pretreatment showed pores and cracks caused by weakening of the cell walls during delignification, which increased yields of reducing sugars.…”

Lignocellulosic biomass fractionation with the use of deep natural eutectic solvents

“…However, after biomass fractionation Figure 5(C) and (D), the samples showed cell deformation and fiber loosening suggestive to the effect of NADES. Through the micrographs obtained it is possible to observe the structural changes by the appearance of cracks, with probable appearance motivated by the dissolution of hemicelluloses and destructuring of the lignocellulosic material, changes such as increased surface area between the raw biomass (A) and the one treated with microwave radiation (D) (Singh et al, 2020).…”