World-wide antimicrobial resistant is biggest threat in global health. It requires the urgent need of multisectoral action for the scientific community to achieve the sustainable development Goals. Due to their antimicrobial properties, silver nanoparticles are potential activates to pathogens, which explains their potential for multiple applications in various fields. In the present studies, we evaluate the antimicrobial properties of a Sargassum polycystum algal extract, an unrivaled green synthetic method for producing -defined shaped seaweed silver nanoparticles. To confirm their structure and size, some characterization techniques are used, such as Absorption spectrophotometer (UV–VIS), Fourier transforms infrared spectroscopy (FTIR), Scanning electron Microscope (SEM), Transmission electron microscopy (TEM) and X-Ray diffraction (XRD). Evaluate the antibacterial and anti-mycobacterial activity using silver nanoparticles. The toxicity study of this silver nanoparticle has been done with the help of zebrafish larva. The biological nanoparticle having good antimicrobial activity against Staphylococcus aureus, Micrococcus luteus, Pseudomonas fluorescens and Candida albicans and also it shows potent activity against MTB H37Rv, SHRE sensitive MTB Rifampicin resistant MTB around 98%. Seaweed nanoparticles had lower toxicity for the survival of the fish larvae. In comparison, other dosages will arrest the cell cycle and leads to death. The present finding revealed that these seaweeds nanoparticles have potential anti-mycobacterial activity against pathogens at low concentrations. This makes them a potent source of antibacterial and anti-TB agents

Objective: Phytochemical is naturally present in the seaweeds which biologically play a significant role. The intention of this study was designed to screen the phytochemical constituents and antimicrobial potential of selected seaweed collected from Rameshwaram and Tuticorin Southern coast of India.Methods: The present study investigated the presence of phytochemical constituents and also total phenol, total carbohydrate and total protein quantity of the brown seaweed. Dictyopteris delicatula, Padina gymnospora, Acanthophora spicifera, Portieria hornemannii and Ulva faciata were extracted with solvents having different polarities like methanol, ethanol, chloroform and water and screened for the phytochemical constituents, total phenol, total carbohydrate, total protein and DPPH with standard procedure. The antibacterial activities of the seaweeds were examined by agar well diffusion method.Results: Among the five seaweeds, U. faciata showed the maximum number of active constituents in the methanol extract likewise P. gymnospora was found to have a number of diligent compounds in ethanol extract. A. spicifera showed minimum compounds in ethanol as well as chloroform extract. Moreover A. spicifera, P. hornemannii have shown the superior quantity of protein and carbohydrate when compared to other species. The scavenging activity of methanol extracts at 5 mg/ml concentration P. hornemannii shows 18.2% and A. spicifera possess 17.1%. In the antibacterial activity, methanol extracts of all the seaweed showed a potential inhibitory activity against B. cereus and P. aeruginosa compared to other pathogens.Conclusion: The crude extract of seaweed manifest preferable antimicrobial and antioxidant activities, hence in the future, it would be good if it is further taken for treatment of human diseases or as new antimicrobial agents to replace synthetic antimicrobial agents.

Carbon dioxide sequestration by microalgae is receiving increased attention in alternative impact of increasing CO₂ in the atmosphere. For this study, we have chosen three different microalgae such as Chlorococcum humicola, Chlorella vulgaris and Scenedesmus quadricauda were treated with 3 W/m² UV-B radiation in different time durations (10, 15, 30, 45 and 60 min) and supplemented with bold basal medium. Parameters such as Total Chlorophyll, protein, Carbohydrate, and CO₂ fixation rate were determined. Based on the parameters Scenedesmus quadricauda is used for carbon sequestration study. Different concentrations of sodium bicarbonate (0.2%–1%) were supplemented to bold basal medium for carbon utilization it can act as an alternative source of atmospheric CO₂. In this maximum amount of chlorophyll content were observed in 0.6% of Sodium bicarbonate. The uttermost amount of CO₂ fixation rate and lipid content was recorded at 0.4% sodium bicarbonate concentration. Finally, the result indicated that Scenedesmus quadricauda could be used for CO₂ mitigation and having a rich source of polyunsaturated fatty acid. Further urea and glucose in the media positively influence growth and CO₂ fixation rate of micro algae. These carbon and PUFA rich microalgae can be used as dietary feed fish usually obtain necessary nutrients via bioaccumulation through the food chain. Thus, this study proves to be an encouraging source of discovery of alternating the dietary source for fish and also helping in carbon utilization process in a natural way.

Biowaste originating from aquaculture sector represents a potential feedstock to produce value-added substances and materials like chitin and chitosan. They are the long chain polymers of N-acetylglucosamine polymers with huge industrial and biomedical significance. Chitin has long been recognized as a useful biomaterial for drug delivery and neurological therapy. Similarly, chitosan oligosaccharide, a short chain polymer derived from chitin/chitosan, has been identified for its potential biomedical applications, including antibacterial, anti-inflammatory, and anti-Alzheimer action. Chitosan nanoparticles are also used extensively in biomedical applications. Here we have critically summarized various methods for the extraction of chitin, chitosan, and chitooligossacharides and chitosan nanoparticle preparation and their diverse biomedical applications.