Bioresource Technology Reports最新文献

Polyhydroxyalkanoate (PHA) is a kind of cellular biopolymers, and a renewable alternative to conventional plastics. To promote low-cost PHA production, this study developed a simple and scalable process to recover this polymer from a phenol-fed mixed culture. Cultures containing >50 % PHA were first acidified then treated with NaClO, leading to digestion of cellular materials by HClO. NaClO dosage, HCl/NaClO ratio, and treatment time were tested for their effects on product Purity and Recovery rate. Compared with NaClO alone which obtained 55–74 % Purity and 57–73 % Recovery, acidification improved the extraction efficiency to 62–83 % Purity and 75–97 % Recovery of cellular PHA. Statistical analysis was performed on dosage, ratio and treatment time. The chemical cost of obtaining 1 kg pure PHA ranged $7–10, but can be greatly reduced by applying a denser culture. However, HClO reduced the molecular weight of the PHA products, which needs to be addressed in future studies.

Vinasse and filter cake (FC) are promising substrates for hydrogen (H₂) production via dark fermentation. Silage, an anaerobic storage technique, helps break down macromolecules into simpler ones like xylose, fructose, and glucose. This study evaluated different ensiling durations (0, 20, 40, 80, and 100 days) on FC and its co-fermentation with sugarcane vinasse for H₂ production, using the digestate for methane (CH₄) production. The inoculum underwent an acid pretreatment to select H₂-producing bacteria. The 40-day ensiling period yielded the best H₂ performance (95 NmLH₂ gVS⁻¹, 43 % H₂ concentration). Longer durations (80 and 100 days) were inefficient. The main metabolic pathways for H₂ production were acetic and butyric acid production. The best CH₄ yield was from 20-day silage (311 NmLCH₄ gVS⁻¹). Predominant microorganisms were Firmicutes and Actinobacteria. Ensiling effectively pre-treats for H₂ and CH₄ production, improving yield, and efficiency.

The main focus involves an in situ approach for the preparation of epoxy nanocomposite (EPLNCNF) coatings composed of hybrid Acacia mangium lignin (LN) and Hibiscus cannabinus cellulose nanofiber (CNF) for bifunctional purposes. Hybrid moieties (LN/CNF) were prepared by a chemo-mechanical method using sustainable tung oil epoxy as the base matrix and 0.25 wt. % isophorone diisocyanate (IPDI) as the cross-linker. The solution casting method is used to cast EPLNCNFs on wood, paper and glass for fire retardant testing, with coatings developed on wood exhibiting more protection than paper and glass coatings. Standard ASTM methods, UL94V, one-stop ignition, and thermogravimetric analysis were carried out on the samples, and EPLNCNF nanocomposite coatings were inferred to be potential fire-retardant materials. The surface morphology of the nanocomposite exhibited uniform dispersion and compactness. The spherical-shaped LN, which is intact within rod-shaped CNFs, is distinctly visible and occupies the interstitial voids within the pristine epoxy. Compared with pristine epoxy coatings, hybrid LN/CNF work synergistically within the epoxy matrix with EPLNCNF nanocomposite coatings, exhibiting extensive cross-linking, strong adhesion, hydrophobicity, solvent and chemical resistance, compactness, mechanical stability, no defects, decreased swelling, high crystallinity, antioxidant activity and thermal stability up to 380 °C. DPPH was used to determine that the antioxidant activity of the nanocomposite was 73.50 %. As a result, the shelf life of the materials can increase for longer durations with potential market value.

Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are commonly found in Louisiana's waterways, specifically in the waterways of Bayou Lafourche and the Intracoastal Canal. In August of 2021, Hurricane Ida flooded levees in Larose, Louisiana, where the bayou and canal intersect, and deposited sediment contaminated with industrial chemicals, antibiotics, and ARB. Many multidrug resistant bacteria were isolated from the sediments. One of the bacterial isolates, Alcaligenes faecalis, was able to use sulfamethoxazole (SMX) as its sole nitrogen source and was resistant at concentrations of 500 mg/L of SMX. The objective of this study was to find out the ability of this new isolate to degrade SMX. When this bacterium was grown on a basic mineral salt medium with SMX as the sole nitrogen source, 39.81 % SMX was removed in the culture, which was statistically significant compared to other treatment conditions. HPLC analysis showed the production of many metabolites. LC/MS confirmed the identity of two metabolites as 3-amino-5-methylisoxazole (3A-5M) and 3-hydroxy-5-methylisoxazole (3H-5M). A. faecalis hydrolyzed SMX to produce 3A-5M which was oxidatively deaminated further to yield 3H-5M with the release of ammonia. This reaction occurred only when there was no other nitrogen source other than SMX was present in the culture medium, which showed that this unique feature of the bacteria could be used to degrade SMX from the contaminated environment.

This study focuses on the transformation of industrial wastes to wealth by utilizing treated sugarcane molasses (TCM) to produce dextran. The fermentation conditions for maximum dextran production were initially optimized using central-composite design in shake-flasks. The highest titer of dextran (60.0 ± 2.0 g/L) was obtained with optimized variables of 150 g/L substrate (TCM), 12.8 g/L yeast extract, 39.8 g/L K₂HPO₄, and 48 h fermentation time. Then, the profiles of dextran production, TCM consumption, and microbial growth were fitted by kinetic models to obtain the following kinetic parameters: 0.35 h⁻¹ maximum specific growth rate (μ_max), 0.48 g dextran/g substrate yield coefficient (Y_ps), 0.07 maintenance coefficient (m_s), and 10.73 g product/g cell growth-associated constant (α). For determining the scale-up factors, the fermentation conditions were replicated in a 3 L fermenter at various stirring speeds (50–250 rpm), and a scale-up strategy based on constant P/V was used to predict the power consumption (1.88–285.51 W) for a pilot-scale of 2000 L working volume fermenter at various stirring speeds (10.8–54 rpm). The dextran produced was characterized using gel permeation chromatography to determine the molecular mass variations (3–4000 kDa) with fermentation conditions. The rheological variations of fermentation broth at different stirring speeds were also studied and related to the molecular mass of the dextran produced. Techno-economic analysis for dextran production explored a gross margin of 22.65 %, a return on investment of 16.80 %, and a pay-back time of 5.95 years.

Phycoremediation of emerging pollutants and heavy metals for treatment technologies is attracted mainly due to low-energy, cost-effective, sustainable, and eco-friendly solutions. Microalgae appear to be a promising candidate for pollutant biosorption and bioaccumulation, with excellent removal potential. However, the right selection of microalgae species for the degradation of specific pollutants remains a major challenge. Phycoremediation could be combined with the existing industrial treatment processes of wastewater as an effective secondary or tertiary stage process, which would enhance the treatment efficiency. This review focuses on the recent trends in bioremediation of wastewater treatment for heavy metals and emerging contaminants' removal, factors influencing pollutant removal, and mechanisms of pollutant degradation. Microalgae efficiently eliminated nutrients along with heavy metals and emerging pollutants up to 83–96 %, 43–100 %, and 18–100 % from different wastewaters. Furthermore, valorization of microalgal biomass for the bioeconomy, challenges associated with wastewater cultivation, and prospects are discussed. This review aims to provide useful information that will aid in the development of commercially viable technological interventions for microalgae-based bioremediation processes in sustainable environments.

This study addresses the multifaceted challenges stemming from the excessive application of manure or digestate, with the aim of mitigating problems of storage, emissions, contamination and transportation. It presents a unique-protocol for efficiently recovering nutrients in the form of struvite, a pure, easy-to-use magnesium ammonium phosphate compound. The objective is to explore struvite production via mono-digestion of poultry manure and co-digestion of various organic wastes, including poultry, dairy, pig manures, and wasted corn silage. Crystals are synthesized under optimized conditions: magnesium/phosphorus ratio of 1.5, pH 9, and mixing at 240 rpm. The process achieves ≥95 % TAN-recovery in moisture-free form for various digestates, with a significant 61.5 % reduction in volatile-fatty-acids. Approximately 0.33–1 g struvite is produced per 10 mL digestate. The study suggests using disodium or monopotassium phosphate for practical implementation, demonstrating the versatility of digestates. Integrating this method into anaerobic digestion promotes the circular-economy and sustainable management of waste nutrients.

The concern to identify a more benign alternative for whitening agents is gaining significant attention in recent investigations. Therefore, this study aimed to investigate the ability of laccase isolated from Trametes polyzona to degrade melanin and explore potential natural phenolic mediators enhancing degradation process. Among phenolic mediators tested, gallic acid showed the most potential for melanin degradation due to 3-fold enhancement, with the highest rate of 77.8 % during a 24-h reaction. The addition of sodium azide inhibited melanin degradation to approximately 56 %, showing the significant role of laccase. The results of Scanning Electron Microscope analysis after treatment showed that the morphology of melanin was significantly altered, with rough and porous surface, as well as small uniform size. However, the untreated melanin had a smooth surface, a round shape, and a larger size. In vitro and molecular docking analyses mutually supported the occurrence of the laccase mediator system in melanin degradation.

Vibriosis, caused by Vibrio harveyi and Vibrio parahaemolyticus, poses a significant threat to aquaculture, resulting in substantial economic losses. Oligosaccharides are known for their ability to improve gut health and prevent vibriosis in aquaculture species. This study explored the fermentative utilization of galacto-oligosaccharides (GOS), manno-oligosaccharides (MOS), and inulin by Lactiplantibacillus plantarum BIOTECH 1074. GOS and glucose were the preferred substrates for L. plantarum growth, producing high levels of lactic acid, propanoic acid, and acetic acid. These compounds showed substantial anti-Vibrio activities, having inhibitory concentration values of 0.252 ± 0.005 and 0.656 ± 0.015 mg total organic acid/mL against V. harveyi, V. cholerae, and V. parahaemolyticus from GOS fermented supernatant. The fermentative capabilities of L. plantarum BIOTECH 1074, in utilizing specific oligosaccharide substrates to produce organic acids with anti-Vibrio potential, offers a promising strategy for enhancing disease management and overall efficiency in aquaculture systems.

Pistachio hull contains water-soluble polysaccharides with prebiotic potential. In polysaccharide extraction, ethanol is commonly used to remove impurities and precipitate polysaccharides. This study compared the efficiency and safety of different washing and precipitating materials to identify a cost-effective method to produce polysaccharides. The extracted polysaccharides were ethanol washed and ethanol precipitated (EWEP), methanol washed and methanol precipitated (MWMP), chemical washed and ethanol precipitated (CWEP), and chemical washed and methanol precipitated (CWMP). Bases on our results, using chemical compounds in washing stage led to a 50% decrease in the amount of extracted polysaccharide. The FT-IR analysis results, probiotic stimulation growth, and cytotoxicity assay showed no difference between the MWMP and EWEP polysaccharides (p > 0.05). The residual methanol, microstructure morphology, monosaccharide composition and antimicrobial activity of MWMP polysaccharide were also measured. We indicated that methanol is a safe, efficient and cost-effective agent for removing impurities and precipitating water-soluble polysaccharides. Further studies are required to explore the physical, chemical and functional characteristics of MWMP polysaccharide.