Search Results (7)

This study investigates the synergistic effects of integrating ozone nanobubbles (generated via a pure oxygen-fed reactor with nanobubble-diffusing air stones) and biofloc technology (BFT) on water quality optimization, pathogenic load reduction, and growth performance enhancement in Pacific white shrimp (Penaeus vannamei) prenursery aquaculture systems. Four treatments were tested: a clear water control (CW), ozonated clear water (CW + O), biofloc (FLOC), and biofloc with ozone (FLOC + O). The FLOC + O group significantly improved water quality, reducing total ammonia nitrogen (TAN) by 61%, nitrite nitrogen (NO₂⁻-N) by 78% compared to CW, and total suspended solids (TSS) by 21% compared to FLOC (p = 0.0015). Ozone application (maintained above 0.3 mg/L, 15 min/day) demonstrated robust pathogen suppression, achieving a sharp reduction in Muscle Necrosis Virus (MNV), a 99.5% inhibition of Vibrio spp. (from 228,885 to 107 CFU/mL), and the clearance of Epistylis spp., as determined via optical microscope. These enhancements directly translated to superior biological outcomes, with the FLOC + O group exhibiting an 82% survival rate (vs. 40% in CW) and 13% higher final body weight (11.65 mg vs. 10.32 mg in CW). The integration of ozone and BFT also accelerated larval development and improved the Zoea II to Mysis I metamorphosis success rate. By maintaining stable microbial communities and reducing organic waste, the combined system lowered the water exchange frequency by 40% and eliminated the need for prophylactic antibiotics. These results demonstrate that ozone–BFT integration effectively addresses key challenges in shrimp prenursery—enhancing disease resistance, optimizing water conditions, and improving growth efficiency. The technology offers a sustainable strategy for the intensive prenursery of Pacific white shrimp, balancing ecological resilience with production scalability. Full article

Farming Chinese perch in aquaculture systems with artificial diets is a new method and developing trend. This method of raising Chinese perch has led to outbreaks of new diseases. In 2022, a disease outbreak occurred among farmed Chinese perch fed an artificial diet in Jiangxi Province, China, during which 50% of the fish died. The clinical signs exhibited by the diseased Chinese perch included decreased physical vitality, anorexia, emaciation, and dorsal fin ulceration with white cysts and flocs. Coinfection with ciliate parasites and an oomycete was found. No pathogenic bacteria were isolated from the microbial test, and the viral detection results were negative. After morphological and 18S or 28S rDNA sequence clustering analysis, the parasites were identified as Epistylis wuhanensis and Zoothamnium sp., while the oomycete was identified as Achlya klebsiana. This article discusses the interaction between parasitic and oomycete coinfections in Chinese perch from the perspective of the characteristics of Chinese perch raised with an artificial diet. The relationships between parasites, oomycete, and fish were also briefly discussed. This is the first report of the coinfection of Chinese perch with Epistylis wuhanensis, Zoothamnium sp. and Achlya klebsiana. Full article

Bioinvasions constitute both a direct and an indirect threat to ecosystems. Direct threats include pressures on local trophic chains, while indirect threats might take the form of an invasion of a microorganism alongside its host. The marine dinoflagellate Hematodinium perezi, parasitizing blue crabs (Callinectes sapidus), has a worldwide distribution alongside its host. In Greece, fluctuations in the blue crab population are attributed to overexploitation and the effects of climate change. The hypothesis of the present study was that blue crab population reductions cannot only be due to these factors, and that particular pathogens may also be responsible for the fluctuations. To investigate this hypothesis, both lethargic and healthy blue crab specimens were collected from three different fishing sites in order to assess the health status of this important species. Together with the lethargic responses, the hemolymph of the infested crabs presented a milky hue, indicating the first signs of parasitic infestation with H. perezi. The histopathological results and molecular identification demonstrated the effect of the presence of H. perezi in the internal organs and their important role in the mortality of blue crabs. Specifically, H. perezi, in three different tissues examined (heart, gills, hepatopancreas), affected the hemocytes of the species, resulting in alterations in tissue structure. Apart from this dinoflagellate parasite, the epibiotic peritrich ciliate Epistylis sp. was also identified, infecting the gills. This study represents the first detection of H. perezi in the eastern Mediterranean, demonstrating that this is the main causative agent of blue crab mortality on Greek coastlines. Full article

Currently composites play an important role in all aspects of engineering and technology, with constantly growing applications. Recently, more attention was focused on natural fillers due to their suitability as reinforcement materials in thermo-plastic matrices which improve the mechanical properties of these polymers. Biofillers are used due to their low cost, high strength rigidity, non-toxicity, biodegradability, and availability. Currently, spent coffee grounds (SCG) are attracting more attention as a natural filler since high amounts of SCG are generated every day (food waste of coffee processing). This study allowed us to determine the long-term effect of activated sludge microorganisms with known technical and technological parameters on the mechanical properties of composites with spent coffee grounds filler. The fittings consisted of high-density poly-ethylene (PE-HD), which was used as the matrix, and a filler based on spent coffee grounds (SCG), which was used as a modifier. It was established that the composition of the composite and its residence time in the bioreactor directly influenced the contact angle value. The shift of the contact angle value is associated with the formation of the biofilm on the tested materials. An increase in the contact angle was observed in the case of all samples tested in the bioreactor, with the lowest values equal to approx. 76.4° for sample A (PE-HD) and higher values of approx. 90° for the remaining composite samples with a coffee grounds filler. The research confirmed that the increased ratio of coffee grounds in the composite results in the increased diversity and abundance of microorganisms. The highest number and the greatest diversity of microorganisms were observed in the case of the composite with 40% coffee grounds after more than a year of exposure in the bioreactor, while the composite with 30% SCG was second. Ciliates (Ciliata), especially the sessile forms belonging to the Epistylis genus, were the most common and the most numerous group of microorganisms in the activated sludge and in the biofilm observed on the samples after immersion in the bioreactor. The conducted research confirms that the use of polymer composite mouldings with a filler in the form of spent coffee grounds as a carrier allows the efficient increase in the population of microorganisms in the bioreactor. Full article

Aerobic granular sludge (AGS) is a promising technology for wastewater treatment. AGS formation belongs to microbial self-aggregation. Investigation of the formation and stability of AGS is widely paid attention to, in particular the structure stability of large size granules. Two types of AGS were developed in two sequencing batch reactors fed by two different wastewaters, respectively. Through confocal laser scanning microscope (CLSM) and scanning electron microscopy (SEM), the structure and composition of granules were analyzed. Filamentous bacteria were observed in granules from synthetic wastewater reactor, while filamentous bacteria and stalked ciliates (Epistylis sp.) were simultaneously found in granules from domestic wastewater reactor. The analytic results show that filamentous bacteria and stalked ciliates acting as skeletons play important roles in the formation and stability of granules. With the bonding of extracellular polymeric substances (EPS), the filamentous bacteria and stalked ciliates could build bridges and frames to promote the aggregation of bacteria; these microorganisms could create a space grid structure around the surface layer of granules to enhance the strength of granules, and the remnants of the stalks could serve as supports to fix the steadiness of granules. Full article

The COVID-19 pandemic and the related measures brought a change in daily life that affected the characteristics of the municipal wastewater and further, of the biological activated sludge. The activated sludge process is the most widely used biological wastewater treatment process in developed areas. In this paper, we aim to show the situation of specific investigations concerning the variation of the physicochemical parameters and biological composition of the activated sludge from one conventional wastewater treatment plant from a metropolitan area. The investigations were carried out for three years: 2019, 2020 and 2021. The results showed the most representative taxa of microorganisms: Microtrix, Aspidisca cicada, Vorticella convallaria, Ciliata free of the unknown and Epistylis and Rotifers. Even if other microorganisms were found in the sludge flocs, their small presence did not influence in any way the quality of the activated sludge and of the wastewater treatment process. That is why we conclude that protozoa (especially Flagellates and Ciliates) and rotifers were the most important. Together with the values and variation of the physicochemical parameters, they indicated a good, healthy, and stable activated sludge, along with an efficient purifying treatment process, no matter the loading conditions. Full article

Peritrichs usually settle on the external surface and gills of crustaceans. However, their physiological effect on the host has not been studied. Respiratory rate is a susceptible index for some factors that affect an organism. To test if ciliates attached to the crustacean gills have a physiological effect, we measured crustacean oxygen consumption in a closed system. Crayfish Cambarellus (Cambarellus) montezumae were collected in Lago Xochimilco in Mexico City and were isolated in chambers. Two peritrich species, Cothurnia variabilis (32.5%) and Epistylis gammari (67.5%), were observed on the gills. The metabolic rate was evaluated by oxygen consumption with a polarimetric oximeter. Statistical analyses demonstrated that a density of ciliates attached to the gills of the crayfish above ~50 individuals increased oxygen consumption with a positive correlation to epibiont density. We conclude that C. variabilis and E. gammari ciliate epibionts attached to the gill of the crayfish Cambarellus (Cambarellus) montezumae cause an increase in metabolic rate. Full article