Identification of Effective Organic Carbon for Biofloc Shrimp Culture System

Effect of Biofloc Technology Enriches the Growth of Litopenaeus vannamei (Boone, 1931)

The use of probiotics in shrimp farms has expanded as an alternative to antibiotics, improving shrimp health, growth, disease control and water quality. However, the efficacy of probiotics in intensive systems using biofloc remains uncertain. This study investigated bioremediation and biocontrol of commercial probiotics using biofloc, analysing water quality and bacterial groups influencing shrimp performance. Thirteen microbial colonies were observed in the biofloc samples, and their evolutionary history was inferred using the neighbour-joining method. Analysis using MEGA6 software revealed 99.6% similarity between colony 1P1 and Virgibacillus sp. and 99.8% similarity between colony 2P2 and Bacillus kochii. The study analysed the biochemical and amino acid content of shrimp cultured using biofloc technology for 85 days. The study found that biofloc-cultured L. Vannamei flesh had higher levels of moisture (31%), ash (15.2%), protein (34%) and lipid (12.6%). No seasonal variations were observed between biofloc samples in winter and summer seasons. Protein levels were found to be appropriate for shrimp growth in both ex situ and in situ biofloc systems. The average growth rate (kg/m2) of biofloc-cultured shrimp was significantly greater than in normal pond shrimp in both samples. The feed conversion ratio in the biofloc tank was lower than in the usual pond-cultured shrimp, possibly due to lower growth rate, lower feeding frequency (2 times per day) and higher density. The growth of L. vannamei shrimp is influenced by stocking density, with higher stocking density affecting the average weight. The study also examined the growth biochemical and amino acid content of shrimp cultured using biofloc technology.

Potential influence of jaggery-based biofloc technology at different C:N ratios on water quality, growth performance, innate immunity, immune-related genes expression profiles, and disease resistance against Aeromonas hydrophila in Nile tilapia (Oreochromis niloticus)

Biofloc technology is increasingly becoming the most promising aquaculture tool especially in places where water is scarce and the land is very expensive. The dynamics of water quality, as well as plankton and microbial abundance, are collectively necessary for successful fish farming. The prospective use of jaggery as a potential carbon source and its influence on water quality, growth performance, innate immunity, serum bactericidal capacity, and disease resistance to Aeromonas hydrophila was investigated in Oreochromis niloticus. A completely randomized design was used in triplicates, where the control group was reared in a water system with no carbon source, while T1, T2, and T3 groups were raised in biofloc systems at C:N ratios of C:N12, C:N15, and C:N20, respectively. Water specimens were collected daily and fortnightly, while blood, serum, and head kidneys were collected at 75 days of experimental period for further analysis. TAN, nitrite, and ammonia values were considerably reduced, while the TSS values elevated significantly in all treated groups compared to the control. Jaggery-based biofloc system (JB-BFT) has a pronounced effect on hematological and growth performance parameters rather than control. Similarly, serum antioxidants, lysozyme, protease, antiprotease and bactericidal capacity were significantly increased (p < 0.05) in the treated groups in a dose-dependent manner. LYZ, TNF-α, and IL-1β genes were upregulated in proportion to C:N ratios with the highest fold in C:N20. Furthermore, fish treated with JB-BFT presented lower cumulative mortalities and better relative levels of production (RLP) after experimental challenge with A. hydrophila compared to control. In conclusion, JB-BFT has a robust influence on Nile tilapia (O. niloticus) innate immunity through favorable innovation of various immune-cells and enzymes as well as upregulating the expression levels of immune-related genes. This study offers jaggery as a new carbon source with unique properties that satisfy all considerations of biofloc technology in an eco-friendly manner.

A promising strategy for nutrient recovery using heterotrophic indigenous microflora from liquid biogas digestate

Nutrient overloading resulting from digestate (effluent of anaerobic digestion process) application has become a major bottleneck for the development of the biogas industry and raised environmental concerns in regions with intensive animal husbandry. Due to this, it is imperative to find low cost and effective alternative to export nutrient from digestate. Among the numerous applications, indigenous microflora has recently been utilized successfully as a biofloc technology in aquatic systems for controlling ammonia and subsequent reduction of feeding cost. Accordingly, performance of the indigenous microflora in undiluted liquid digestate of chicken manure was evaluated in this study to recover nutrients and produce high-value biomass under aerobic heterotrophic mode in batch shaking experiments. The results showed that 68% of phosphate was recovered and 97% of total nitrogen was removed from the liquid digestate. Additionally, >6 g L^-1 of dry biomass was simultaneously produced and featured with up to 65% crude protein without pathogens, 10.9% lipids, 10.7% ash and 19.6 MJ kg^-1 gross energy. Therefore, the produced biomass could be used either as an alternative sustainable source for animal or fish feeding or as a substrate for energy applications.