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Biofloc formation is affected by the addition of carbon sources and the adequate aeration supply with a proper arrangement of aeration units. Apart from molasses was commonly used as carbon sources, the effect of different nitrogen types was also critically important in the biofloc formation. This study aimed to evaluate the effect of different aeration units and nitrogen types on the biofloc formation using bioflocculant-producing bacteria as inoculum. Experimental set-up was prepared with two types of aeration units (i.e.: air stone and aerotube) and three nitrogen types (i.e.: fish meal, grounded pellet and pellet). Water quality parameters, water physical appearance, biofloc volume and shrimp biomass were observed within 30 days of the study period. There were no significant difference (P ≤ 0.05) between the water quality parameters, however, biofloc volume and shrimp biomass showed a significant difference with the aeration units. Nitrogen types using pellet showed positive results with the formation of biofloc, while there was no formation of biofloc in the other treatments. Consequently, injection of bioflocculant-producing bacteria for the rapid formation of biofloc was recommended with a proper installation of aerotube units and pellet as a nitrogen type. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) occurrence in farmed aquatic organisms has already been the prime priority of researchers due to the food security concerns for human consumption. A number of commercially important aquaculture systems have already been investigated for MPs pollution but the mud crab (Scylla sp.) aquaculture system has not been investigated yet even though it is a highly demanded commercial species globally. This study reported the MPs pollution in the mud crab (Scylla sp.) aquaculture system for the first time. Three different stations of the selected aquafarm were sampled for water and sediment samples and MPs particles in the samples were isolated by the gravimetric analysis (0.9% w/v NaCl solution). MP abundance was visualized under a microscope along with their size, shape, and color. A subset of the isolated MPs was analyzed by scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) for the surface and chemical characterization respectively. The average MPs concentration was 47.5 ± 11.875 particles/g in sediment and 127.92 ± 14.99 particles/100 L in the water sample. Fibrous-shaped (72.17%) and transparent-colored (59.37%) MPs were dominant in all the collected samples. However, smaller MPs (>0.05–0.5 mm) were more common in the water samples (47.69%) and the larger (>1–5 mm) MPs were in the sediment samples (47.83%). SEM analysis found cracks and roughness on the surface of the MPs and nylon, polyethylene, polypropylene, and polystyrene MPs were identified by FTIR analysis. PLI value showed hazard level I in water and level II in sediment. The existence of deleterious MPs particles in the mud crab aquaculture system was well evident. The other commercial mud crab aquafarms must therefore be thoroughly investigated in order to include farmed mud crabs as an environmentally vulnerable food security concern. [Display omitted] • MPs were found in both water and sediment samples of the mud crab culture system. • MPs were more abundant in sediment samples than in water samples. • Fibrous and transparent colored MPs were the most common types of MPs particles. • The types of MPs characterized were nylon, PE, PP, and PS. [ABSTRACT FROM AUTHOR]

The environmental impacts of aquaculture wastewater and biowaste from shellfish processing have become a major challenge to aquaculture expansion and sustainability. There is need to develop measures for the wastewater treatment and proper recycling of the biowaste. In this study, dry legs of giant freshwater prawn (Macrobrachium rosenbergii) were chemically processed into chitin and chitosan for use as coagulant in the coagulation/flocculation of real aquaculture wastewater. Box-Behnken design in response surface methodology (RSM) was used to establish the optimum operating conditions of chitosan dosage, pH, and settling time for removal of turbidity and colour. Statistical models were generated for the independent variables after which the model was validated. Results showed that dry legs of M. rosenbergii are mainly composed of minerals (76.36%) with low level of chitin (9.29%) and chitosan (7.02%). With 80% solubility and 91% degree of deacetylation (DDA), the smooth and none porous chitosan showed great potential of a good coagulant. This study recorded that dosage (5 mg/L), pH (5) and settling time of 11.25 min successfully removed 93.84% turbidity while 99.89% colour removal was achieved at 20 mg/L at 7.5 pH and 30 min settling time. The high level of minerals in the legs was responsible for the low chitin and chitosan yields while high turbidity and colour removals were attributed to the solubility and DDA. [Display omitted] • Impacts of aquaculture wastewater reduced by coagulation/flocculation using chitosan coagulant. • The legs of Macrobrachium rosenbergii are inedible and discarded, thereby creating source of environmental pollution. • The conversion of M. rosenbergii legs into chitosan as bio-coagulant in aquaculture wastewater treatment, thus cleansed solid waste from the processing factories. [ABSTRACT FROM AUTHOR]

Microalgae are well known as autotrophic microorganisms in aquaculture wastewater treatment, however their role in the aquaculture system is rarely explored. The purpose of this study is to evaluate the influence of adding microalgae, Chlorella sp. UMT LF2, on the functionality for bioremediation and growth performance of Whiteleg shrimp, Litopenaeus vannamei in the nursery phase reared in a control culture system. Secondly, the response surface methodology (RSM) was used to investigate further on the optimal condition for the harvesting process of excess microalgae biomass using bio-flocculant from the filamentous fungus, Aspergillus niger. The experimental set-up with Chlorella sp. additions were compared to the control group without the microalgae addition based on the water quality, microalgae biomass and shrimp growth performance. Water samples were collected and underwent in-situ and ex-situ involving nine physicochemical parameters. The results showed that introducing microalgae with zero water exchange as treatment tanks reduced the NH 3 , NO 2 − and PO 4 3− during the intermediate until the two days before the 30-day culture period's end. Microalgae also enhanced shrimp survival and growth performance significantly 89% as compared to the control, 68%. Furthermore, the culture with the addition of microalgae maintained pH stability and enhanced dissolved oxygen during daytime in the culture water. Therefore, this finding confirmed that Chlorella sp. UMT LF2 addition is promising in improving rearing environment and nursery performance for L. vannamei in culture system. However, further research is required to demonstrate the harvesting by-product from the culture system and the potential applications. [ABSTRACT FROM AUTHOR]

The physical profile and chemical composition of growing media are vital in evaluating fish waste filtration efficiency and plant growth performance in aquaponics. The present study reported and compared the physical and chemical evaluation of the novel fabricated Kaolina, gravel, and commercially used lightweight expanded clay aggregate (LECA) as growing medias in aquaponics. Field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy (FESEM-EDX) was utilized to analyze the growing media's chemical composition and structural characterization. The resultant effect of these growing medias on water quality and the growth performance of Clarias gariepinus and Lactuca sativa were also reported. Kaolina exhibited an excellent physical profile (42.95 ± 1.39%) in water absorption capacity as compared to LECA (35.90 ± 1.28%) and gravel (1.97 ± 0.25%), showing a significant difference at p < 0.05. The addition of 25% w/w Musa paradisiaca peel in the fabrication of Kaolina gives an added value of 88.0% of K and 100% of P elements, which show a significant difference (p < 0.05) compared to LECA. The results obtained reveal a better daily growth rate (DGR) and relative growth rate (RGR) of L. sativa at 0.57 ± 0.02 cm day−1 and 0.21 ± 0.00 g day−1, respectively. Results indicated that the porous structure of growing media could contribute to the high-water retention capability and slow the water desorption process. Hence, it could increase the ability of the growing media to hold nutrients for plant intake, resulting in higher removal percentage of nutrients in aquaponics system. Kaolina gives the highest nutrient removal percentage of TAN (96.86 ± 1.50%), NO 2 − (83.56 ± 1.27%), NO 3 −(77.55 ± 0.48%), and PO 4 3− (79.46 ± 0.42%). The results also shown growing media has considerable impacts on nutrient removal, which contribute to the aquaponic productions. [Display omitted] • Nutrient supplies through Kaolina are more natural and sustainable. • Kaolina eliminate chemical nutrient supply practiced in aquaponics. • Water absorption and retention capacity of Kaolina is more stable. • Kaolina provided essential micronutrients and optimized physical characteristics. • Significant yield of L. sativa and C. gariepinus in Kaolina than LECA and gravel. [ABSTRACT FROM AUTHOR]

Microplastics pollution has become a threat to aquaculture practices, as nearly all farming systems are saturated with microplastics (MPs) particles. Current research on MPs is limited considering their effects on aquatic organisms and human health. However, limited research has been conducted on potential cures and treatments. In today's world, bioremediation of needful parameters in different culture systems is being successfully practiced by introducing floc-forming bacteria. Researchers had found that some bacteria are efficacious in degrading microplastics particles including polyethylene (PE), polystyrene (PS), and polypropylene (PP). In addition, some bacteria that can form floc, are being used in fish and shellfish culture systems to treat toxic pollutants as the heterotrophic bacteria use organic compounds to grow and are effective in degrading microplastics and minimizing toxic nitrogen loads in aquaculture systems. In this review, the ability of biofloc bacteria to degrade microplastics has been summarized by collating the results of previous studies. The concept of this review may represent the efficacy of biofloc technology as an implicit tool in the fish culture system restricting the MPs contamination in water resources to safeguard ecological as well as human health. • Biofloc technology has a potential impact on the MPs pollution reduction. • Specific biofloc producing bacteria are found to be a MPs degrader. • Biofloc producing bacteria can degrade microplastics and convert them to environment-friendly non-toxic compounds. • Microplastics pollution free aquaculture system could be established through the biodegradation of MPs by biofloc bacteria. [ABSTRACT FROM AUTHOR]

• B.enclensis was identified as bioflocculant-producing bacteria based on morphological and flocculating activity. • Bioflocculant-producing bacteria, B. enclensis yielded 93% of flocculation efficiency. • Microplastics was incubated with B. enclensis , changes in physical and chemical properties were observed by SEM and FTIR. • The microplastics served as the sole source of carbon for the bacterial culture that was grown in Mineral Salt Medium. • Inoculation of B. enclensis with microplastics provide eco-friendly treatment for microplastic pollution in aquaculture. [ABSTRACT FROM AUTHOR]

Chitosan is a biopolymer compound which is made up of β-1,4 glycosidic bonds. Due to its peculiar nature, chitosan has found applications in science and engineering, food processing, medicine, agriculture and wastewater treatment. Isolation of chitin and chitosan from dry powder shell of Penaeus monodon was achieved through chemical treatment with acid and alkali. The conventional sequence of chemical isolation of chitosan follows the order of demineralization (DM), deproteinization (DP), decoloration (DC) and deacetylation (DA). This was altered into four different sequential protocols: SQ1(sequence 1), SQ2 (sequence 2), SQ3 (sequence 3) and SQ4 (sequence 4) to study its effect on the physicochemical properties of chitosan. 1 M HCl and 2 M NaOH was applied at 1:15 m/v ratio for 3 h to achieve demineralization and deproteinization, respectively. Furthermore, for all sequences, deacetylation of chitin to produce chitosan was achieved by application of 50% NaOH at 100 °C for 3 h. In the present study, the chemical structures of chitosan were confirmed through FTIR, XRD and SEM. The highest chitin (20.17 ± 1.58 g) and chitosan (14.81 ± 2.05 g) yields were obtained from SQ4 (DC-DP-DM-DA). In addition, results of other important characteristics of chitosan such as solubility and degree of deacetylation (DDA); reported as 68.34 ± 2.64% and 82.30 ± 3.01% respectively were also highest in SQ4. The smooth and non-porous P. monodon chitosan with high solubility and DDA (especially SQ4) is most suitable in wastewater treatment, however not fit in medicine as filler due to its poor flowability. [Display omitted] • Chitosan is a biopolymer processed industrially by chemical process. • The traditional method of chemical isolation: demineralization, deproteinization, decoloration and deacetylation can be re-ordered for better yield and characteristics. • A change in the sequential arrangement of the conventional steps affects yield and quality of chitosan. [ABSTRACT FROM AUTHOR]

The Rapid Alert System for Food and Feeds (RASFF) is a monitoring and notification tool and food safety-related database developed by the European Commission. This study evaluated the microbiological safety of foods originating from the Asia-Pacific region in the past two decades (2000–2020) by analysing incidences and trends of notifications and alerts on the RASFF database. The highest number of notifications were for foods imported from India and Thailand as foods imported from these two countries constituted more than half (54%) of the notifications recorded on the RASFF database for the entire Asia-Pacific region from 2000 to 2020, compared to ANZ (Australia and New Zealand), which had very low notifications (1.2% = 23/1873). Among the 2121 notifications of pathogenic microorganisms, consisting of 14 genera, Salmonella was the most predominant as approximately 7 out of every 10 pathogens isolated from foods imported from the Asia-Pacific Region in the past two decades (74%, 1560/2121) were Salmonella species. More than 95% of pathogen species notifications for fruits and vegetables imported from India and Bangladesh were associated with betel leaves. Among the nuts, nut products and seeds, sesame seeds were the main food item contaminated by Salmonella , and these accounted for 87% of total Salmonella notifications. Across the food categories, there was a statistically significant reduction in the number of notifications associated with seafoods over the years (r = −0.73, p = 0.0001). Although a statistically significant increase in notifications for fruits and vegetables (r = 0.66, p = 0.008) was recorded between 2000 and 2014, more recent years (2015–2020) have been associated with reducing trends in the number of notifications associated with this food type (r = −0.85, p = 0.03). Results indicate that imported foods may be potential vehicles for the transmission of clinically relevant microorganisms. Studies of this nature can potentially encourage countries to implement policies that improve export quality. • RASFF pathogen notifications analysed for Asia Pacific food imports (2000–2020). • 1873 notifications reported over 2 decades across 29 notifying countries. • Imported foods can potentially transmit clinically relevant microorganisms. • Salmonella was the predominant pathogen (7 out of every 10 pathogens). • Inconsistent actions in responses to notifications by different EU member states. [ABSTRACT FROM AUTHOR]