Chitin, chitosan and chitooligosaccharides as potential growth promoters and immunostimulants in aquaculture: A comprehensive review.

There is a stable growth in aquaculture production to avoid seafood scarcity. The usage of eco-friendly feed additives is not only associated with aquatic animal health but also reduces the risk of deleterious effects to the environment and consumers. Aquaculture researchers are seeking dietary solutions to improve the growth performance and yield of target organisms. A wide range of naturally derived compounds such as probiotics, prebiotics, synbiotics, complex carbohydrates, nutritional factors, herbs, hormones, vitamins, and cytokines was utilized as immunostimulants in aquaculture. The use of polysaccharides derived from natural resources, such as alginate, agar, laminarin, carrageenan, fucoidan, chitin, and chitosan, as supplementary feed in aquaculture species has been reported. Polysaccharides are prebiotic substances which are enhancing the immunity, disease resistance and growth of aquatic animals. Further, chitin (CT), chitosan (CTS) and chitooligosaccharides (COS) were recognized for their biodegradable properties and unique biological functions. The dietary effects of CT, CTS and COS at different inclusion levels on growth performance, immune response and gut microbiota in aquaculture species has been reviewed. The safety regulations, challenges and future outlooks of CT, CTS and COS in aquatic animals have been discussed in this review.

Black soldier fly (Hermetia illucens) larvae as potential feedstock for the biodiesel production: Recent advances and challenges.

Black soldier fly larvae (BSFL) Hermetia illucens is fastest growing and most promising insect species especially recommended to bring high-fat content as 5th generation bioenergy. The fat content can be fully optimized during the life-cycle of the BSFL through various organic dietary supplements and environmental conditions. Enriched fat can be obtained during the larval stages of the BSF. The presence of high saturated and unsaturated fatty acids in their body helps to produce 70 % of extractable oil which can be converted into biodiesel through transesterification. The first-generation biodiesel process mainly depends on catalytic transesterification, however, BSFL had 94 % of biodiesel production through non-catalytic transesterification. This increases the sustainability of producing biodiesel with less energy input in the process line. Other carbon emitting factors involved in the rearing of BSFL are less than the other biodiesel feedstocks including microalgae, cooking oil, and non-edible oil. Therefore, this review is focused on evaluating the optimum dietary source to produce fatty acid rich larvae and larval growth to accumulate C16-18 fatty acids in larger amounts from agro food waste. The process of optimization and biorefining of lipids using novel techniques have been discussed herein. The sustainability impact was evaluated from the cultivation to biodiesel conversion with greenhouse gas emissions scores in the entire life-cycle of process flow. The state-of-the-art in connecting circular bioeconomy loop in the search for bioenergy was meticulously covered.

Green and eco-friendly approaches for the extraction of chitin and chitosan: A review.

Chitin is one of the most diverse and naturally occurring biopolymers, and it is mainly present in crustaceans, insects, and fungi. Chitosan is derived from chitin by deacetylation process. It is important to note that the conventional chemical method of extracting chitin includes disadvantages and it poses various environmental issues. Recently, the green extraction techniques have perceived substantial development in the field of polymer chemistry. A variety of methods have been successfully developed using green extraction techniques for extracting chitin and chitosan from various resources. It includes the use of ionic liquids (ILs), deep eutectic solvents (DES), microbial fermentation, enzyme-assisted extraction (EAE), microwave-assisted extraction (MAE), ultrasonic-assisted extraction (UAE), subcritical water extraction (SWE), and electrochemical extraction (ECE). In this review, the extraction of chitin and chitosan using greener approaches were summarized. In addition, challenges, opportunities and future perspectives of green extraction methods have also been narrated.

Dieckol: a brown algal phlorotannin with biological potential.

Dieckol [C36H22O18], is a naturally occurring phlorotannin found in some brown algal species. Dieckol is gaining more attention in the scientific community for its potential biological activities. It has been exhibited a broad spectrum of therapeutic functions including anti-bacterial, anti-cancer, anti-oxidant, anti-aging, anti-diabetic, neuroprotective, and other medicinal applications. Distinct emphasis has been given to extraction, purification, and biomedical applications of dieckol. This critical review comprises of in vitro, in vivo, and in silico biological properties of dieckol. An attempt has been made to evaluate the effectiveness, therapeutical application, and mechanism of dieckol against various diseases. The pharmacological significance, current status and the dosage of multifunctional dieckol and its mechanisms have been discussed in this review. Dieckol plays an important role in apoptosis induction via inhibiting the PI3K, AKT, mTOR and FAK signaling molecules. Dieckol remarkably inhibited the lipid accumulation in high fat diet induced animal models. Dieckol, a multifaceted compound will be beneficial in attenuating the action of various diseases and it could be a potential pharmaceutical and nutraceutical compound. Therefore, the combined effects of dieckol with existing drugs and natural compounds will be studied in future to optimize its benefits. Besides limited information on the toxicological action and dosage administration of dieckol on the human was reported to date. Overall, dieckol is a prospective health-promoting compound for the development of a novel drug against numerous diseases.

Application of marine-derived polysaccharides as immunostimulants in aquaculture: A review of current knowledge and further perspectives.

The use of antibiotics in the feeds of cultivable aquatic animals has been generally practised to reduce infectious diseases as well as to improve the survival and growth. In recent years, many countries ban to aquatic animals due to the use of large amount of antibiotics and chemotherapies, thus alternative novel strategies are need to promote the growth of aquatic animals and control the pathogens. Dietary supplementation of marine-derived polysaccharides (MDPs) is one of the potential substitutes for antibiotics in aquatic animal feeds. Recently, the use of dietary MDPs in the aquaculture animals has been focused with much interest. In aquaculture, MDPs are used as prebiotic substance which is mostly accepted as a nutritional component for improving the growth performance and health conditions. Hence, present review is a comprehensive and an updated collection of available research reports on different MDPs (alginate, fucoidan, carrageenan, laminarin, ulvan, galactan, agar, chitin and chitosan), route of administration, dosage and applications for improving aqua feeds with emphasis on its effects on growth, biochemical indices, immune response, gut microbiota and disease resistance of aquaculture animals. This review describes the sustainability of global aquaculture production by providing a best alternative to harmful antibiotics, thereby meeting the emerging consumer demand for antibiotic-free aquatic food products.