Browsing by Author "Senadheera, U. E"

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Open Access
A novel solid-state, multi-layered biodegradable microbial inoculant system for rice straw composting: biocapsule design, characterization, and performance evaluation
(Frontiers Media SA, 2026-04-17) Senadheera, U. E; Jasintha Jayasanka, D; Hewawasam, C; Udayanga, D; Takimoto, Y; Nakayama, T
Lignocellulolytic microbial inoculants are widely used to enhance lignocellulosic waste composting, but their efficacy is often limited by environmental stress and uncontrolled release when conventional liquid inoculants are used. This study introduces a multi-layered biocapsule structure that sustains lignocellulolytic microbial activity and evaluates its composting efficiency through control experiments. A three-layered biodegradable biocapsule was designed using a rice straw biocomposite, humic acid, activated carbon, corn starch, carboxymethyl cellulose, and calcium alginate beads with encapsulated Klebsiella–Enterobacter consortium immobilized on hydroxyapatite nanoparticles. The biocapsule comprises a rice straw outer biocomposite shell in the outermost layer, a moisture retention hydrogel in the middle, and the encapsulated bacteria in calcium alginate beads in the core. The designed biocapsule was used in three treatments: intact biocapsule, powdered biocapsule, and a control (without inoculants), and the composting efficacy was evaluated against Sri Lankan Standards for compost products. Calcium alginate beads achieved 78.29% ± 9.57% and 84.45% ± 6.04% bacterial encapsulation efficiency and bacterial release, respectively, with heavy bacterial colonization in beads. The entire biocapsule reached 56.16% ± 1.65% biodegradation in 7 days. Intact biocapsule enhanced early lignocellulolysis, faster pH neutralization, and reduced electrical conductivity to 0.62 ± 0.00 while sustaining prolonged thermogenesis above 55 °C for 25 days. The intact biocapsule significantly improved compost nutrient availability, increasing total nitrogen, phosphorus, and potassium levels by 71.89%, 83.0%, and 60.66%, respectively, while achieving a total organic carbon loss of 53.30% and a Carbon: Nitrogen ratio decline of 72.83%.
Open Access
Coordinated lignocellulolysis: topological analysis reveals coordinated lignocellulolysis in Klebsiella–Enterobacter-mediated rice straw degradation via surface delignification and cellulose crystallinity modulation
(Microbiology Society, 2026-05-12) Senadheera, U. E; Jayasanka, D.J; Hewawasam, C; Udayanga, D; Takimoto, Y; Tadachika, N
Surface-sterilized Oryza sativa AT362 straw was screened for endophytic ligninolytic and cellulolytic bacteria using colour unit reduction and Congo Red decolorization assays. Ligninolytic Klebsiella variicola AKL1104 and cellulolytic Enterobacter chuandaensis AKC1108, biocompatible, were inoculated at a 1:1 ratio and incubated in 1% (w/v) rice straw broth at 37 °C for 7 days. Topological changes due to degradation were conducted using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) for 9 days. During t=9 d, SEM shows vascular tissue perforation with tunnels, indicating K. variicola mediated-delignification, allowing E. chuandaensis to sequentially degrade cellulose. XRD revealed a cellulose crystallinity decline from 30.08% on t=0 d to 11.76% on t=9 d. Electron microscopy and crystallite size calculations in t=6 d (6.81 nm) and t=9 d (90.16 nm) indicate self-assembly of cellulose fibrils. FTIR and XPS analysis indicated crystalline cellulose transformation to amorphous cellulose as the lateral order index dropped from 0.776±0.006 to 0.503±0.007, while surface lignin coverage was reduced from 5.01 to 2.20%, respectively.