Central Institute of Fisheries Technology

The conventional sun drying of Kappaphycus alvarezii often results in quality deterioration, restricting its food applications beyond carrageenan production. Since seaweed farming is a low-cost livelihood for coastal communities, there is a need for simple and affordable pre-treatments that farmers can easily adopt to preserve and improve product quality. To address this, hot water blanching was investigated as a pre-treatment strategy. Blanching seaweed at 70 °C for 60 s was found as the optimal condition for improving nutritional quality, whereas 60 °C for 30 s was the most effective condition for enhancing antioxidant properties. Blanching (70 °C for 60 s) produced a 3 h reduction in drying time with lesser moisture content, increased fat (1.89%), carbohydrate (46.09%), and crude fiber (6.76%) content without compromising protein levels. Lightness improved by 39.44%, mitigating negative sensory impacts and enhancing suitability for food formulations. Although some mineral leaching occurred, essential minerals such as potassium, magnesium, and manganese remained within the Indian Council of Medical Research recommended daily allowance limits. Sodium decreased to a safer dietary level, while phosphorus, calcium, copper, iron, and zinc levels increased, enriching the overall mineral profile. The blanched seaweed (60 °C for 30 s) showed a 64.22% increase in 2, 2-diphenyl-1-picrylhydrazyl radical scavenging activity, 120.83% in ferric-reducing antioxidant power, and 143.73% in total antioxidant activity. These improvements were linked to greater retention of betulin, a potent antioxidant terpenoid, confirmed through high-resolution liquid chromatography–mass spectrometry. These findings indicate that blanching induces temperature and time-dependent enhancement in the quality of K. alvarezii, supporting its application in functional foods.

A 65-day comparative study was conducted to evaluate the effects of three culture systems Biofloc (T1), Bio phyton (T2), and Aquamimicry (T3) alongside a control (T4) on growth performance, water quality parameters, proximate composition, and microbial dynamics of Catla catla fingerlings (initial weight: 0.69 ± 0.02 g). Millet was used as a carbon source in all treatments, whereas no carbon source was added in the control. Among all treatments, Biofloc technology (T1) exhibited superior performance across most evaluated parameters. Fish reared under T1 showed significantly higher body weight gain (39.49 ± 4.35%), specific growth rate (2.30 ± 0.01), feed efficiency ratio (0.88 ± 0.07), protein efficiency ratio (2.20 ± 0.17), lipid efficiency ratio (14.67 ± 1.18), and survival rate (90.21 ± 1.77), along with a lower feed conversion ratio (1.15 ± 0.09), compared to other treatments. Water quality parameters in T1 remained within optimal ranges throughout the experimental period, reflecting efficient nutrient recycling and enhanced microbial activity. Microbial analysis through total plate count (TPC) revealed significantly higher microbial abundance in both water and fish gut samples under Biofloc (T1), followed by Bio phyton (T2), Aquamimicry (T3), and the control (T4). In water samples, T1 (3.5107CFU/ml) and T2(3.2107 CFU/ml) recorded the highest TPC values, while similar trends were observed in fish gut samples, with T1 exhibiting the maximum microbial load. The elevated microbial populations in biofloc systems likely contributed to improved nutrient assimilation, health status, and growth performance of fish by promoting beneficial heterotrophic microbial communities. the findings demonstrate that millet-based biofloc technology effectively enhances microbial abundance, water quality, and growth performance of C. catla, suggesting its suitability as a sustainable and productive aquaculture strategy.

The increasing frequency of bacterial diseases in aquaculture has necessitated the use of several antibiotics, including enrofloxacin (ENF), a broad-spectrum fluoroquinolone. The pharmacokinetic (PK) and pharmacodynamic (PD) data on ENF under tropical aquaculture conditions remain scarce. This study investigated the PK profile, tissue accumulation, and depletion pattern of total active fluoroquinolone (ENF + CIP) in Nile tilapia Oreochromis niloticus following a single oral dose of 10 mg/kg biomass. The ENF demonstrated rapid absorption, with peak plasma concentration (Cmax) of 1.33 ± 0.21 μg/mL at 0.59 h (Tmax), and extensive tissue distribution, particularly in bile (Cmax: 16.26 ± 0.50 μg/mL) and intestine (Cmax: 7.08 ± 0.28 μg/g). Elimination half-lives (t1/2β) varied among tissues, with prolonged persistence in skin (t1/2β: 693.18 h) and gills (t1/2β: 237.47 h), indicating slow depletion. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ENF indicated its high effectiveness against Aeromonas hydrophila (0.20 μg/mL), while Streptococcus agalactiae exhibited comparatively lower sensitivity (MIC: 1.56 μg/mL; MBC: 6.25 μg/mL). The PK/PD integration revealed that ENF achieved optimal therapeutic levels against A. hydrophila, but suboptimal levels for S. agalactiae under a single-dose regimen. These findings underscore the need for tailored dosing strategies and highlight the importance of pharmacokinetic and microbiological data for responsible antibiotic use in aquaculture.

Klebsiella quasipneumoniae is a recently described species that can be differentiated from Klebsiella pneumoniae. However, in clinical settings, they are frequently misidentified as K. pneumoniae. In this study, our objective was to conduct genomic characterization and bioinformatics analysis of K. quasipneumoniae subsp. quasipneumoniae (KpII-A) isolated from a sample obtained from a retail fish market in Assam, India. Notably, this particular isolate was identified as K. pneumoniae when identified using BD Pheonix™ M50 (BD Difco, USA). This represents a serious pitfall of conventional microbiological methods for distinguishing between K. pneumoniae and K. quasipneumoniae. In this connection, identifying differences in nuclear gene content is key to avoid misidentification. The isolate was confirmed to be KpII-A using species identification by Mash Screen and whole-genome sequencing by the Illumina platform. We report the draft genome sequence of this strain, comprising of 53 contigs with an average GC content of 58.11%. The annotation revealed 5,095 protein coding sequences, 69 tRNA genes, and 4 rRNA genes. The isolated strain acknowledges the presence of oqxA, oqxB, fosA, and blaOKP-A-3 antimicrobial resistance genes (ARGs). Additionally two phage genomes were detected in contigs 3 and 19 of the bacterial genome. Based on the multilocus sequence typing and genome sequencing, the isolate was identified as a novel sequence type, ST5655, within the species K. quasipneumoniae under the phylogroup KpII-A. The presence of antimicrobial resistance genes in KpII-A, isolated from retail fish samples, raises concerns regarding transmission across barriers in ecological niches and possible transmission to consumers. Given that fish may serve as a potential vehicle for ARG transmission, our findings are highly relevant and paramount to human health. Moreover, our study supports the robustness of the sequence-based microbial identification.

CDOM, an important ocean colour product, accounts for 90% of non-water UV absorption in the upper ocean. CDOM absorption triggers photochemical reactions resulting in the release of greenhouse gases and alters microbial bioavailability of organic matter. The three different approaches for retrieving adg(λ) from satellite data were validated using aCDOM(λ) generated from OC-CCI-derived remote sensing reflectance (Rrs) and in situ measured aCDOM(λ). The multiple linear regression (MLR) model performed better than the two exponential decay models in quantifying CDOM in the UV region. The better performance of Rrs-based algorithms indicated that absorption-based algorithms need considerable improvement when compared to algorithms based on the combined absorption by detrital matter and CDOM (adg(λ)). As a result, the absorption-based algorithm was modified as the ASCDOM algorithm, which demonstrated improved retrieval at 275, 355, 38 and 412nm for aCDOM(λ). The ASCDOM algorithm's strong statistical performance highlights its accuracy in retrieving satellite products for water quality evaluations and ocean colour monitoring.

Eutrophication refers to a process in which aquatic ecosystems, including lakes, estuaries, or slow-moving streams, become inundated with surplus nutrients that promote rampant plant growth, such as algae, periphyton, and invasive aquatic weeds. The rise in plant growth, commonly referred to as an Algal Bloom, leads to a decline in dissolved oxygen levels, diminished light penetration, and the death of benthic phytoplankton in the aquatic environment. The breakdown of deceased plant material can then lead to the death of additional organisms. The term “bloom” refers to the swift proliferation and build-up of microalgal or cyanobacterial species, which can be recognized by the alteration in the colour of water surfaces. This discoloration can manifest in various hues, including the commonly recognized red (often called red tide), as well as different shades of brown, green, yellow, blue, or purple. Harmful Algal Blooms (HABs) generate toxins that pose threat to humans, animals, and aquatic ecosystems, although some blooms are benign. These events predominantly occur in the summer months within both marine and freshwater settings, resulting from a variety of factors that encourage algal proliferation, including increased water temperatures, greater sunlight exposure, and nutrient availability, which present dangers to humans, wildlife, and aquatic ecosystems. Consequently, it is crucial to conduct prompt in situ evaluations of algal blooms and their toxins, without the need for intricate sample preparation, to gauge the potential threats and facilitate timely interventions. Raman Spectroscopy, along with its advanced variants including surface-enhanced Raman Spectroscopy, tip-enhanced Raman Spectroscopy, coherent anti-Stokes Raman Spectroscopy, and stimulated Raman Scattering Microscopy, provides a rapid, sensitive, and non-invasive tool for the identification of algal bloom species and their toxins, thereby offering a more adaptable solution for environmental monitoring. This review highlights the progress made in analytical techniques and explores the dual characteristics of algal blooms, which serve as both ecological phenomena and contributors to the transport and prevalence of microplastics pollution. A comprehensive investigation is crucial to evaluate the adverse effects of microplastics on microalgal diversity and aquatic ecosystems, employing sophisticated methodologies in conjunction with Raman spectroscopy. • Algal blooms induce hypoxic zones that perturbs aquatic ecosystems. • Excess phosphorus and nitrogen runoff drives harmful algal bloom growth. • Raman spectroscopy facilitates the swift monitoring of detrimental algal blooms. • Cutting-edge Raman methods evaluate algal toxins with reduced sample preparation.