This study aims to evaluate a Pacific white shrimp and Nile tilapia integrated system using biofloc technology with or without the addition of the microalgae Scenedesmus obliquus and with or without fish feed supplementation in a two-factor 62-day experiment. The shrimp (2.16 ± 0.01 g) were reared under a density of 400 shrimp m⁻³ and the fish (1.53 ± 0.12 g) were reared under a density of 522 fish m⁻³. The microalgae was added to the culture water two times a week. Growth performance, sludge production, and water microbiology were evaluated. Fish feed and the microalgae addition improved fish final biomass in 58% and 14%, respectively (p < 0.05). Fish survival was significantly higher when microalgae was added (93.9 ± 1.8%) compared with the treatments without microalgae addition (86.2 ± 7.6%) (p < 0.05). The yield of the overall system was higher in the treatments with fish feed supplementation (4.2 ± 0.2 kg m⁻³) compared with no addition (3.9 ± 0.2 kg m⁻³) (p < 0.05). These results suggest that fish feed supplementation at the rate of 1% of the biomass and microalgae inoculation can improve fish growth performance and system yield, without affecting sludge production and water microbiology. This work is an expansion of a conference paper with the same title.

The aquaculture industry faces many challenges regarding the intensification of shrimp rearing systems. One of these challenges is the release of excessive amounts of nitrogen and phosphorus into coastal areas, causing disruption in nutrient cycling and microbial equilibrium, which are important for coastal productivity. Biosecurity within the shrimp rearing systems can also be compromised by disruption to the nutrient fluxes, and as consequence the microbiome of the system. In certain conditions, these changes could lead to the blooming of potentially pathogenic bacteria. These changes in the external microbiome of the system and the constant fluctuations of nutrients can affect the intestinal microbiome of shrimp, which is involved in the growth and development of the host, affecting nutrient absorption, regulating metabolic processes, synthesising vitamins, modulating the immune response and preventing growth of pathogenic bacteria. It has been suggested that specific changes in the intestinal microbiome of Litopenaeus vannamei may be an avenue through which to overcome some of the problems that this industry faces, in terms of health, growth and waste. Recent research, however, has focussed mainly on changes in the intestinal microbiome. Researchers have overlooked the relevance of other aspects of the system, such as the microbiome from the benthic biofilms; zooplankton, plankton and bacterioplankton; and other sources of microorganisms that can directly affect the microbial status of the intestinal and epiphytic communities, especially in rearing systems that are based on intensification and microbial maturation processes, such as a biofloc system. It is therefore necessary to place holobiome studies into context, including the ‘holobiome of the aquaculture system’ (microbiomes that make up the culture system and their interactions) and not only the intestinal microbiome. Thus, we describe factors that affect the shrimp microbiome, the methodology of study, from sampling to bioinformatic workflows, and introduce the concept of the ‘holobiome of the aquaculture system’ and how this enables us to promote the intensification, biosafety and eco-efficiency of shrimp farming. The holobiome perspective implies a greater investment of resources and time for research, but it will accelerate the development of technology that will benefit the development and sustainability of the aquaculture industry.

Microalgae offer distinct advantages as a nutritional source for aquaculture and as a means of wastewater bioremediation. Studying the phycosphere bacteria and understanding their complex interactions is essential to optimizing high-quality biomass growth. This study aimed to isolate, characterize, and identify bacteria from the phycosphere of marine microalgae and to determine their potential to enhance growth, metabolism, and bioremediation capabilities of Chaetoceros calcitrans in stress nutrient-poor media simulating aquaculture wastewater enriched with nitrate, nitrite, or phosphorus. Bacterial characterization included tests for auxin and siderophore production, biofilm formation, amylase activity, phosphate solubilization, mobility, and antagonism evaluation. When Alteromonas macleodii, Bacillus cereus, and Marinobacter sp. were selected and then enriched (10⁷ CFU/mL) in co-culture with C. calcitrans, growth levels significantly increased in four of six Synthetic Aquaculture Wastewater (SAW) media. Pigment levels were higher in five of six SAW media, and lipid levels were higher in SAW rich in nitrite (SAWni50) and phosphorus (SAWpho50). In addition, C. calcitrans with or without the bacterial consortium demonstrated excellent phosphorus bioremediation, achieving 67.6% average removal in SAWpho50. Nitrate and nitrite assimilation rates were approximately 10% in SAWna and SAWni50. This study marks the inaugural identification of these bacteria as microalga growth-promoting bacteria (MGPB) for enhancing growth and lipid and pigment production in C. calcitrans, and it also documents a maximum of 69.13% phosphorus removal.

The pursuit of sustainable alternatives has spurred interest in plant-derived bioherbicides with multi-target actions to combat resistance. This study explored the herbicidal potential of Agave lechuguilla extract (AGE) against the widely problematic weed Chenopodium album L. (lambsquarters). Various methods, including germination assays, biochemical profiling, measurements of antioxidant enzyme activity, isothermal microcalorimetry, and both macroscopic and microscopic morphological analyses, were employed to evaluate the effects of AGE relative to glyphosate (1.5%). The results indicated that AGE inhibited seed germination in a concentration-dependent manner, with the 30 g/L dose exhibiting the most significant effect. Treatment with 30 g/L of AGE led to a notable decrease in total carbohydrate content and catalase activity, an increase in total lipids, and an enhancement of glutathione reductase activity. Additionally, it suppressed metabolic heat output and severely disrupted root and cellular architecture, resulting in a reduction of cell area by 51.1%. In contrast, glyphosate primarily increased lipid content and induced near-complete metabolic suppression while causing distinct morphological and enzymatic alterations. The findings demonstrate that AGE functions as a multi-target pre-emergence bioherbicide, disrupting processes related to germination, metabolism, oxidative balance, and morphology through mechanisms that differ from the single-target action of glyphosate. This underscores its potential for sustainable weed management.