Biodegradability and eco-friendliness are the most importance topic to consider in the development of new products. Commercial hydrogels for agriculture applications are made from fully synthetic polymers, which is non-biodegradable and harmful to environment. The utilization of polysaccharide in hydrogels production has sparked the rise of biodegradable hydrogels (BHs). However, using it alone results in poor mechanical properties and very fast degradation. Therefore, combining it with other materials as a composite is necessary. This article reviewed the development of BHs in the last 5 years. Classifications, materials resources, preparation methods, biodegradability of BHs, seeds germination and plant growth performance are critically investigated. Fundamental concepts such as definitions and application methods of BHs are described. Finally, important conclusions and outlook have been mentioned at the end of this article.

Land degradation can cause food insecurities and can damage ecosystems. This study highlights the potential of cyanobacteria (Anabaena variabilis, Spirulina platensis, Scytonema javanicum, and Nostoc commune), along with bacteria (Bacillus sp. SSAU-2), and their consortia to form biological soil crust, restoring soil properties and promoting plant growth. The efficiency of soil improvement was characterized by physiochemical parameters such as phosphate solubilization, %TOC, pH, and salinity. Scanning electron microscopy and a pot experiment were utilized to observe the morphological and soil improvement studies. Bacterial inoculation resulted in significant improvements in soil fertility, such as exopolysaccharide, organic carbon, organic matter, phosphorus content, and total soil porosity. Cyanobacteria consortia were more effective than monocultures at improving soil fertility and promoting barley plant development. The potential value of selected cyanobacteria and bacterial consortia as a useful tool for the restoration of degraded land is demonstrated experimentally by this study.

Selenium fertilizers (Se-fertilizers) were applied to promote the growth of plant and improve the Se content in crops. However, traditional Se-fertilizers have low utilization efficiency of Se due to adsorption or leaching. Herein, Alg-g-Polyacrylamide/Se orange peel polysaccharide (AP/SeOPP) hydrogel was prepared and characterized by FT-IR, SEM, XRD and XPS. The swelling behaviors of AP8/SeOPP3 in different saline solution were investigated. Meanwhile, the rheological properties of AP8/SeOPP3 were studied. The water-retention ratio of AP8/SeOPP3 at -0.08 MPa were 84.9 %. The water-holding capacities of soil with AP8/SeOPP3 (1 wt%) was 33.8 % at 20th day. The pot experiments showed that the Se content of Chinese cabbage treated by AP8/SeOPP3 of 2 wt% was 2.67 mg/kg. Compared with control treatment, the average stem height and fresh weight of Chinese cabbage fertilizered by AP8/SeOPP3 were higher than that treated by AP8 hydrogel. The release mechanism indicated that there was the ion exchange between Cl-, PO43- , SO42- in sandy soil and SeO32- in AP8/ SeOPP3 hydrogel. This work provides a feasible strategy for promoting vegetable growth and achieving Seenrichment of crops in arid and semi-arid region.

Suitable planting systems are critical for the physicochemical and bioactivities of strawberry (Fragaria x ananassa Duch.) polysaccharides (SPs). In this study, SPs were prepared through hot water extraction, and the differences in physicochemical characteristics and bioactivities between SPs derived from elevated matrix soilless planting strawberries (EP-SP) and those from and conventional soil planting strawberries (GP-SP) were investigated. A higher extraction yield was observed for EP-SP (5.88%) than for GP-SP (4.67%), and slightly higher values were measured for the average molecular weight (632.10 kDa vs. 611.88 kDa) and total sugar content (39.38% vs. 34.92%) in EP-SP. In contrast, a higher protein content (2.12% vs. 1.65%) and a more ordered molecular arrangement were exhibited by GP-SP. Monosaccharide composition analysis revealed that EP-SP contained higher levels of rhamnose (12.33%) and glucose (49.29%), whereas GP-SP was richer in galactose (11.06%) and galacturonic acid (19.12%). Thermal analysis indicated only minor differences in decomposition temperatures (approximately 225-226 degrees C) and thermal stability between the samples. However, GP-SP showed a higher enthalpy change (Delta Hg = 18.74 J/g) compared to EP-SP (13.93 J/g). Biological activity assays revealed that GP-SP generally exerted stronger non-enzymatic glycation inhibition at both early and final stages (IC50: 7.47 mg/mL vs. 7.82 mg/mL and 11.18 mg/mL vs. 11.87 mg/mL, respectively), whereas EP-SP was more effective against intermediate alpha-dicarbonyl compounds (maximum inhibition of 75.32%). Additionally, GP-SP exerted superior alpha-glucosidase inhibition (IC50 = 2.4583 mg/mL), in line with kinetic and fluorescence quenching analyses showing a higher enzyme-substrate complex binding affinity (Kis = 1.6682 mg/mL; Ka = 5.1352 x 105 M-1). Rheological measurements demonstrated that EP-SP solutions exhibited a pronounced increase in apparent viscosity at higher concentrations (reaching 3477.30 mPas at 0.1 s-1 and 70 mg/mL) and a stronger shear-thinning behavior, while GP-SP showed a comparatively lower viscosity and lower network order. These findings suggest that different planting systems significantly affect both the molecular structures and functionalities of SPs, with GP-SP demonstrating enhanced hypoglycemic and anti-glycation properties. It is therefore recommended that suitable planting systems be selected to optimize the functionality of plant-derived polysaccharides for potential applications in the food and pharmaceutical industries.

The agricultural industry prioritizes minimizing crop yield losses caused by pests, making it essential to develop effective, safe and sustainable pesticide formulations. Hydrogels are promising carriers for pesticide delivery, due to their high surface area, large pore volume, and pore size. In this study, we synthesized Cassia fistula (CA-g-AA) and its derivative carboxymethylated Cassia fistula-grafted polysodium acrylate hydrogel (CMCA-g-AA) using free radical polymerization, with N, N'-methylene bisacrylamide (MBA) as a crosslinker, for the ex-situ encapsulation of dinotefuran. Characterization was performed using FTIR, 13C CPMAS-NMR, SEM, TGA, rheology, and XRD. The maximum swelling capacity of hydrogels was investigated in distilled water. CA-g-AA and CMCA-g-AA hydrogels exhibited a dinotefuran loading percentage of 37 and 39% and released dinotefuran for 26 and 29 h, respectively. The dinotefuran release kinetics was analyzed by using the Korsmeyer-Peppas and Higuchi models. Under drought like conditions, CMCA-g-AA-treated soil sustained plant growth for 7 days, compared to CA-g-AA (5 days) and untreated soil (3 days). The novel hydrogel CMCA-g-AA enhanced soil water absorption and retention along with highlighting its potential for extended pesticide release. Thus, the developed CMCA-g-AA hydrogel is an efficient strategy for sustainable agriculture.

Stenotrophomonas rhizophila JC1 and its extracellular polysaccharides (EPS) have been shown to effectively adsorb heavy metals in previous studies. The fermentation conditions of EPS by S. rhizophila JC1 were optimized using the Box-Behnken design (BBD). The composition, structural characteristics, and heavy metal adsorption capacity of EPS were systematically evaluated. The alleviation mechanism of Pb2+ stress on alfalfa was investigated through EPS inoculation. The maximum EPS yield reached 0.313 %. EPS consisted of glucose, glucosamine, galactose, and mannose in a molar ratio of 12.20:1:22.29:1.68. EPS also contained four distinct polymers with molecular weights of 623,683.71 Da, 144,072.27 Da, 105,892.21 Da, and 51,094.79 Da. The adsorption processes conformed to the pseudo-second-order model and Langmuir isotherm model. High Pb2+ concentrations significantly reduced germination percentage, germinative force, root length, fresh weight, and soluble protein, inhibited photosynthesis, exacerbated oxidative stress, and caused damage to the antioxidant system, thereby inhibiting seedling growth. EPS at low concentrations can promote alfalfa seed germination and mitigate Pb2+ stress by reducing the aforementioned damage. This study highlights the potential of EPS in soil remediation and enhancing plant resistance to heavy metal stress.

The accumulation of heavy metals in the soil not only causes serious damage to the soil ecosystem, but also threatens human health through the food chain. Exopolysaccharides have the functions of adsorbing and chelating heavy metals and reducing their bioavailability in the soil. In our study, exopolysaccharide-producing bacteria with a high efficiency in adsorbing cadmium (Cd) and lead (Pb) were screened from heavy metal-contaminated farmland. Through pot experiments, the influence of functional strains on the size distribution, heavy metal content, and bacterial community structure of soil aggregates in lettuce was studied using high-throughput sequencing technology. The results show that 11 strains secreting exopolysaccharides were initially screened from heavy metal-contaminated soil. Among them, strain Z23 had a removal rate of 88.6% for Cd and 93.2% for Pb. The rate at which Cd was removed by strain Z39 was 92.3%, and the rate at which Pb was removed was 94.4%. Both strains belong to Bacillus sp. Strains Z23 and Z39 induced the formation of Fe2Pb(PO4)(2), Cd-2(PO4)(2), and Pb2O3 in the solution. The pot experiments showed that strains Z23 and Z39 increased (19.1 similar to 23.9%) the dry weight and antioxidant enzyme activity of lettuce roots and leaves, while reducing (40.1 similar to 61.7%) the content of Cd and Pb. Strains Z23 and Z39 increased the proportion of microaggregates (<0.25 mm) and the content of exopolysaccharides in rhizosphere soil and reduced (38.4-59.7%) the contents of available Cd and Pb in microaggregates, thus inhibiting the absorption of heavy metals by lettuce. In addition, the exopolysaccharide content and the bacterial community associated with heavy metal resistance and nitrogen (N) cycling (Patescibacteria, Saccharimonadales, Microvirga, and Pseudomonas) in microaggregates were key factors affecting the available heavy metal content in soil. These results show that the exopolysaccharide-producing bacteria Z23 and Z39 reduced the absorption of Cd and Pb by lettuce tissues, thus providing strain resources for the safe utilization of soils that exceed heavy metal standards for farmland and for reducing the heavy metal content in vegetables.

Chitosan (CTS), a natural biopolymer derived from chitin, has garnered significant attention owing to its potential chemical, biological, and physical properties, such as biocompatibility, bioactivity, and biosafety. This comprehensive review traces the historical development of CTS-based materials and delves into their specific applications across various fields. The study highlights the evolution of CTS from its initial discovery to its current state, emphasizing key milestones and technological advancements that have expanded its utility. Despite the extensive research, the synthesis and functionalization of CTS to achieve desired properties for targeted applications remain a challenge. This review addresses current problems such as the scalability of production, consistency in quality, and the environmental impact of extraction and modification processes. Additionally, it explores the novel applications of CTS-based materials in biomedicine, agriculture, environmental protection, and food industry, showcasing innovative solutions and future potentials. By providing a detailed analysis of the current state of CTS research and identifying gaps in knowledge, this review offers a valuable resource for researchers and industry professionals. The novelty of this work lies in its holistic approach, combining historical context with a forward-looking perspective on emerging trends and potential breakthroughs in the field of CTS-based functional materials. Therefore, this review will be helpful for readers by summarizing recent advances and discussing prospects in CTS-based functional materials.

The exopolysaccharide (EPS) produced by Pantoea alhagi NX-11, referred to as alhagan, enhances plant stress resistance, improves soil properties, and exhibits notable rheological properties. Despite these benefits, the exact bio-synthetic process of alhagan by P. alhagi NX-11 remains unclear. This study focused on sequencing the complete genome of P. alhagi NX-11 and identifying an alhagan synthesis gene cluster (LQ939_RS12550 to LQ939_RS12700). Gene annotation revealed that alhagan biosynthesis in P. alhagi NX-11 follows the Wzx/Wzy-dependent pathway. Furthermore, transcriptome analysis of P. alhagi NX-11 highlighted significant upregulation of four glycosyltransferase genes (alhH, wcaJ, alhK, and alhM) within the alhagan synthesis gene cluster. These glycosyltransferases are crucial for alhagan synthesis. To delve deeper into this process, two upregulated and uncharacterized glycosyltransferase genes, alhH and alhK, were knocked out. The resulting mutants, Delta alhH and Delta alhK, showed a notable decrease in EPS yield, reduced molecular weight, and altered monosaccharide compositions. These findings contribute to a better understanding of the alhagan biosynthesis mechanism in P. alhagi NX-11.

Bacteria can synthesize a broad spectrum of multifunctional polysaccharides including extracellular polysaccharides (EPS). Bacterial EPS can be utilized in the food, pharmaceutical, and biomedical areas owing to their physical and rheological properties in addition to generally presenting low toxicity. From an ecological viewpoint, EPS are biodegradable and environment compatible, offering several advantages over synthetic compounds. This study investigated the EPS produced by Klebsiella oxytoca (KO-EPS) by chemically characterizing and evaluating its properties. The monosaccharide components of the KO-EPS were determined by HPLC coupled with a refractive index detector and GC-MS. The KO-EPS was then analyzed by methylation analysis, FT-IR and NMR spectroscopy to give a potential primary structure. KO-EPS demonstrated the ability to stabilize hydrophilic emulsions with various hydrophobic compounds, including hydrocarbons and vegetable and mineral oils. In terms of iron chelation capacity, the KO-EPS could sequester 41.9 % and 34.1 % of the most common iron states, Fe2+ and Fe3+, respectively. Moreover, KO-EPS exhibited an improvement in the viscosity of aqueous dispersion, being proportional to the increase in its concentration and presenting a non-Newtonian pseudoplastic flow behavior. KO-EPS also did not present a cytotoxic effect indicating that the KO-EPS could have potential applications as a natural thickener, bioemulsifier, and bioremediation agent.