Sustainable Abstraction of Bio-Polymer from Seafood Trash used for Soil Drenching and Analyzed for the Plant Growth Enhancer

Chitosan is a biopolymer formed from chitin, which is present in crustacean exoskeletons such as crabs and shrimp. Chitosan is a natural and linear polysaccharide derived from chitin by a chemical process that includes deproteinization, demineralization, and decolorization, and it is made by deacetylating chitin, which involves removing the acetyl groups from the polymer chain. (Figure 1). Chitosan has become beneficial and highly appreciated as a natural biodegradable high molecular polymer chemical that is a non-toxic and bioactive agent due to its fungicidal activities and elicitation of defensive systems in plant tissue. Chitin and chitosan are both polysaccharides that are chemically identical to cellulose, with the only difference being the presence or absence of nitrogen, which is absent in cellulose (Bautista-Baños et al., 2006). Chitin, a linear polysaccharide comprised of (1-4)-linked 2-acetamido-2-deoxy-b-D-glucopyranose units (Hu et al., 2007) (Dutta et al., 2002), is nature'ssecond most common type of polymerized carbon. Even though it is not present in organisms that produce cellulose, it is classified as a cellulose derivative. It has a similar structure to cellulose, but it has an acetamide group (-NHCOCH ) at the 3 C position. Molluscs, crustaceans, insects, fungi, algae, and other creatures make around 10 billion tons of chitin each year. 2 FIGURE 1: Structure of Chitosan after deacetylation from Chitin The blue crab (Callinectes sapidus) (Figure 2) has a natural range that extends from Nova Scotia to northern Argentina, including Bermuda and the Antilles. The life cycle of blue crabs is similar to that of other estuarine-dependent species in the Gulf of Mexico. The blue crab sustains one of the Gulf of Mexico'smost important commercial and leisure fisheries. Blue crabs were traditionally exploited by locals for immediate consumption; nevertheless, the first commercial mud crabs eventually reached local markets and formed a major component of the local crab fishery (Ikhwanuddin et al., 2011). Crab flesh is used in a variety of ways in the food business, including as an ingredient in culinary items. However, the crab shell is also beneficial in terms of cancer prevention and as a natural weight loss supplement. Chitosan, a polysaccharide, is also found in crab shells.

FIGURE 2: Blue crab (Callinectes sapidus)

Chitosan is the resultant material, and it has several unique features that make it valuable in a range of applications. When chitosan comes into contact with water, it forms a gel-like material, which is one of its most remarkable features. Because of its features, it is beneficial in a variety of sectors, including food packaging and wastewater treatment. Chitosan also possesses antibacterial characteristics, which make it valuable in medicinal applications such as wound healing and drug delivery. Furthermore, chitosan has been demonstrated to have potential use in agriculture, where it may be utilized as a natural pesticide or fertilizer. Because of its biodegradability, cationic nature, film-forming capacity, antibacterial characteristics, chelating capabilities, water-holding capacity, pH sensitivity, biocompatibility, and adhesion qualities, chitosan is a flexible and important agent in agriculture. It may be used to enhance soil, control disease, regulate nutrients, and promote sustainable agricultural methods. Its features are pH-adjustable, making it appropriate for organic and sustainable activities. Researchers are always looking for new methods to exploit its benefits for better agricultural yield and environmental sustainability. The degree of N-acetylation (DA) of chitosan determines its characterization, which affects not only its physicochemical properties but also its immunological activities (Mahlous et al., 2007). The functional qualities of chitin and chitosan are influenced by physicochemical parameters, which vary depending on the crustacean species and method of manufacture. The physicochemical characteristics of various preparations will differ, particularly the degree of deacetylation, solubility, viscosity, and molecular weight. To efficiently use chitinous products for specific applications, the functional characteristics of chitin and chitosan products should be carefully evaluated (Cho et al., 1998). The presence of free amine groups throughout the chitosan chain affects its solubility, allowing it to dissolve in diluted aqueous acidic solutions. Chitosan derived from crab shells has been shown to have several agricultural advantages. One significant advantage is its ability to improve soil structure by boosting porosity and water-holding capacity. This promotes root growth and nutrient absorption in plants. Chitosan has been found to improve plant development by promoting seed germination and boosting plant biomass, in addition to improving soil structure. It can also assist in minimizing the demand for artificial fertilizers by increasing the availability of nutrients in the soil.

Chitosan stimulates several defensive mechanisms to increase plant tolerance to a wide range of biotic and abiotic stresses, including drought, cold, salt, and water-related difficulties.(Ali et al., 2021) It has been proven that chitosan treatment increased chlorophyll content, hence increasing tomato growth under salt-induced stress conditions. (Wang et al., 2021) Under salt stress, maize height, and main root length were dramatically reduced, whereas shoot and root dry weights were both reduced, and sodium absorption increased. Salt stress dramatically reduced maize seedling photosynthesis, including photosynthetic rate, stomatal conductance, intercellular CO concentration, and transpiration rate. (Jiao et al., 2024) 2 The use of chemical fertilizers to improve soil nutrition has increased agricultural production in recent decades (Mącik et al., 2020). However, there are numerous known disadvantages to continuously applying chemical fertilizers to the soil, such as increasing irrigation requirements, suppressing phyto-beneficial microbes in the soil, and negatively impacting soil ecology, despite some additional benefits, such as ease of handling and predictable results (Bisht and Chauhan, 2020). Simultaneously, the physical, chemical, and biological health of arable land has deteriorated due to excessive chemical use and changes to traditional agricultural methods(Chaudhary et al., 2020). As a result, with dwindling land resources and soil biological potential, the health of diverse agricultural production systems, as well as total biological resources, require proper attention. Under these circumstances, there is a compelling case for using microorganisms in integrated plant management systems to improve plant performance (Saberi-Riseh and Moradi-Pour, 2021). Chitosan, being a polysaccharide, works as a bioremediation molecule, stimulating the activity of beneficial soil microbes such as Bacillus spp., fluorescent Pseudomonas spp., Actinomycetes, Mycorrhiza, and Rhizobacteria. This affects the rhizosphere'smicrobial balance, favoring beneficial bacteria. Bioremediation of soil disturbed with a variety of heavy metals was helped by chitosan treatment in conjunction with mycorrhizal inoculation (Angelim et al., 2013). It encapsulates a consortium of various PGPR within chitosan aided in delivery while also stimulating the development and activity of the bacteria for bioaugmentation and biostimulation of hydrocarbon-polluted soils. Bacillus subtilis is a fungal pathogen and one of the most extensively used biopesticides in agriculture. B. subtilis produces chitinases in its growth media (Chen et al., 2010). The addition of chitosan to the carrier material increased B. subtilis multiplication and fungicidal effect, as well as the control of Fusarium wilt in pigeon pea and crown rot in peanut induced by Aspergillus niger. The addition of chitosan increased B. subtilis effectiveness against powdery mildew in strawberries (Lowe et al., 2012). It also improves soil water retention behavior by indirectly conditioning the soil (Pandey and De, 2017). The microorganisms included in biofertilizers maintain the earth'snatural nutrition cycle while increasing soil organic matter. Using biofertilizers leads to cultivating healthy plants while also enhancing soil health and sustainability. Chitosan-encapsulated microbial biofertilizer benefits tomato crops by improving nutrient absorption, disease resistance, and root growth. (Isabel et al., 2024). Overall, the usage of chitosan in agriculture has the potential to raise crop yields while also improving soil health over time. The current study aimed to develop value-added products from blue crab waste in the extraction and processing of chitosan, as well as their influence on soil drenching with plant growth enhancement.