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Biofloc technology improves water quality and promote the growth of beneficial bacteria community in shrimp culture. However, little is known about the bacteria community structure in both water and gut of cultured organisms. To address this, the current study characterised the metagenomes derived from water and shrimp intestine samples of novel Rapid BFTTM with probiotic and clearwater treatments using 16S V4 region and full length 16S sequencing. Bacteria diversity of water and intestine samples of Rapid BFTTM and probiotic treatments were similar. Based on the 16S V4 region, water samples of >20 mm biofloc had the highest abundance of amplicon sequence variant (ASV). However, based on full length 16S, no clear distinction in microbial diversity was observed between water samples and intestine samples. Proteobacteria was the most abundant taxon in all samples based on both 16S V4 and full length 16S sequences. Vibrio was among the highest genus based on 16S V4 region but only full length 16S was able to discern up to species level, with three Vibrios identified--V. harveyi, V. parahaemolyticus and V. vulnificus. Vibrio harveyi being the most abundant species in all treatments. Among water samples, biofloc water samples had the lowest abundance of all three Vibrios, with V. vulnificus was present only in bioflocs of <20 mm. Predicted functional profiles of treatments support the beneficial impacts of probiotic and biofloc inclusion into shrimp culture system. This study highlights the potential displacement of opportunistic pathogens by the usage of biofloc technology (Rapid BFTTM) in shrimp culture. [ABSTRACT FROM AUTHOR]

Chitin is the second most abundant polysaccharide, produced mainly as an industrial waste stream during crustacean processing. Chitin can be derived into chitosan through the deacetylation process. Conversion of shrimp waste into chitosan via the deacetylation process could be considered a practical approach for shell waste remediation. In this study, chitosan's physicochemical characteristics extracted from two types of Pacific white leg shrimp, L. vannamei's shell (i.e., rough and smooth), were compared with commercial chitosan. The yield, moisture, ash, solubility, water and fat binding capacity were measured. The degree of deacetylation (DDA) was calculated using FTIR, and their chemical Structure was confirmed using XRD and SEM-EDS. Both extracted chitosan showed no significant difference in yield, moisture, ash, solubility and water binding capacity but showed a significant difference with commercial chitosan. Moreover, the fat binding capacity of commercial chitosan showed the lowest percentage (408.34 ± 0.83%) as compared to extracted chitosan (smooth shell 549.59 ± 12.48%; rough shell 500.55 ± 12.10%). The DDA indicated that extracted chitosan from the smooth and rough shell was considered good chitosan as compared to commercial chitosan with 84.08 ± 1.27%, 80.78 ± 0.79% and 74.99 ± 1.48%, respectively. Additionally, the presence of hydroxyl and amino groups from FTIR and a good crystallinity index was recorded using XRD of extracted chitosan. Based on observed characteristics, shrimp shell waste from L. vannamei can achieve chitosan standard quality as a biopolymer and highly potential to be applied in various industrial applications. [ABSTRACT FROM AUTHOR]

Biofloc technology is being applied increasingly in shrimp aquaculture. Many countries have adopted this technology to increase shrimp aquaculture production. Owing to its major importance, this study was conducted to identify the bacterial population from biofloc aquaculture shrimp pond water of Singkir Laut, Kedah, Malaysia. Samples of mature biofloc were collected from the biofloc pond water at different shrimp ages (day of culture [DOC]): DOC30, DOC60 and DOC90. Overall, 43 sequences of bacterial species were blasted, which were identified as Exiguobacterium spp., Bacillus spp., Vibrio spp., Acinetobacter junii, Cobetia marina, Rheinheimera aquimaris and Pseudoalteromonas spp. These bacterial species were identified mostly from heterotrophic plate count agar. The bacterial species of Exiguobacterium aestuarii, Exiguobacterium profundum and Exiguobacterium aurantiacum were identified with 16S rRNA gene sequence similarities of 98.45–99.44%. Bacterial species of Bacillus pumilus, Bacillus velezensis, Bacillus cereus, Bacillus safensis and Bacillus subtilis were identified with 16S rRNA gene sequence similarities of 98.81–99.21%. Bacterial species of Vibrio diazotrophicus, Vibrio diabolicus, Vibrio natriegens and Vibrio harveyi were identified with 16S rRNA gene sequence similarities of 98.03–99.19%. Bacteria from Rheinheimera aquimaris were also identified with 16S rRNA gene sequence similarities of 98.69–99.26%; this bacterium is a novel bacterium identified from biofloc samples of the present study and has not been reported from biofloc samples in any previous study. Exiguobacterium spp. from the novel strains of E. aestuarii and E. profundum were identified as dominant, with 23 of 43 samples isolated from a shrimp pond at time points DOC30, DOC60 and DOC90; these bacteria are Gram‐variable rod‐shaped organisms that are capable of producing extracellular enzyme activity to break down chemical structures, thereby helping to remove organic compounds from aquaculture waste. Exiguobacterium spp. are usually identified in tidal flat sediments and on muddy sea coasts. This discovery is consistent with the site of the shrimp pond near to a muddy beach area, which might be the source of seawater leading to the predominance of this type of bacteria in the biofloc samples in the studied pond. [ABSTRACT FROM AUTHOR]

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Biofloc technology was known to improve the shrimp growth performance and water quality in several ways. The application of bacterial booster was proven to accelerate the development of biofloc in the culture treatments as well as help improve the water quality, shrimp growth performance and yield production. Due to its importance, a study was conducted to identify the effect of biofloc application using Rapid BFT™ microbial booster formulation versus clear water system to improve shrimp growth performance and water quality condition. Study was conducted for 80 days with every 7 days of interval of data collection. Overall, biofloc treatments were identified successfully in improving the shrimp growth performance and also effectively reduced the nutrient concentrations of total ammonia nitrogen (TAN) from the biofloc culture treatments until the end of culture periods. Nitrate (NO3-) from biofloc treatments was also identified in lower concentration as compared to control of clear water system. The average daily growth (ADG) was at 0.12g much better from biofloc treatments as compared to control with ADG 0.08g of clear water system. The specific growth rate (SGR) was 5.47%/day in biofloc and 2.82%/day in control treatments which identified higher and much better from biofloc about 2.65%/day differences between biofloc and clear water. Meanwhile, the final body weight achieved was much higher from biofloc about 9.55 grams compared with control about 7.06 grams from the same day of culture, DOC80 which recorded at the end of cultured period. The first sampling was started at DOC7 where the average initial weight of shrimp in biofloc treatment was 0.117 grams and 0.077 grams identified in control. The highest biomass achieved from biofloc treatments also much better around 11.0 kg compared with control that produced 7.1 kg as the higher biomass produced. There was only yellow and green colony of Vibrio identified from the TCBS culture and no occurrence of luminescent colony from harmful Vibrio harveyi detected. Therefore, it can be concluded that biofloc technology of Rapid BFT™ help improves the water quality of ammonia nitrogen level in water columns and inhibits pathogenic Vibrio to the culture species as well as help improving the shrimp growth performances in more effective way. [ABSTRACT FROM AUTHOR]

Study on the microscopic composition of biofloc in closed hatchery culture system was carried out to determine the interaction between the aggregation flocs in the bioremediation process for the decomposition and degradation of organic matter loaded in the shrimp culture tanks. The study was done for 105 days of culture period in zero water exchange. All of the organic loaded in the culture tanks identified comes from the shrimp feces, uneaten fed, and the decomposed macro- and microorganisms died in the culture tanks. All of the microscopic organisms in the biofloc were identified using Advance microscopes Nikon 80i. From the present study, there were abundances and high varieties of phytoplankton, zooplankton, protozoa, nematodes and algae species identified as aggregates together in the flocs accumulation. All of these microscopic organisms identified implemented the symbiotic process together for food supply, become the algae grazer, act as natural water stabilizer in regulating the nutrients in culture tank and serve as decomposer for dead organic matter in the water environment. Heterotrophic bacteria identified from Pseudomonas and Aeromonas family consumed the organic matter loaded at the bottom of culture tank and converted items through chemical process as useful protein food to be consumed back by the shrimp. Overall it can be concluded that the biofloc organisms identified really contributed as natural bioremediation agents in zero water exchange culture system to ensure the water quality in the optimal condition until the end of culture period. [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]