Presence Of Microalgae Research Articles

Metabolomics reveals that tris(1,3-dichloro-2-propyl)phosphate (TDCPP) causes disruption of membrane lipids in microalga Scenedesmus obliquus

Tris(1,3-dichloro-2-propyl)phosphate (TDCPP) is one of the most widely used organophosphate ester flame retardants. The presence of TDCPP in surface waters and aquatic organisms have been reported worldwide, yet the ecological risk of TDCPP on microalgae is rarely studied. We investigated the biotransformation of TDCPP and its toxicity on the microalga Scenedesmus obliquus using an untargeted metabolomics approach. Exposure to TDCPP resulted in a dose-response decrease of micoalgal biomass. In the presence of microalgae, TDCPP concentration in the media decreased by 25.3–40.6% after 5 days. TDCPP metabolites were identified in the media including hydrolysis and hydroxyl-substituted dechlorination products. A dose-response separation of metabolic profiles of microalgae was observed, with effect seen at the lowest concentration of 10 µg/L tested, which is slightly higher than environmentally relevant concentrations. Differentiated metabolites identified include 52 lipids and 6 polar metabolites. Analysis of altered lipid pathways suggests that microalgal cells reinforce thylakoid membranes (function to protect photosynthesis) by compromising the integrity of plasma membrane (function to protect cellular substances) and extraplastidial cellular membranes. Changes in the polar metabolites might indicate osmotic stress and improved NO signaling after TDCPP exposure. Consistent with perturbation of membrane lipids, further experiment confirmed that exposure to 10 mg/L TDCPP resulted in significant (p < 0.01) plasma membrane damage. This study indicates biotransformation and the membrane damage toxicity mechanism of TDCPP on S. obliquus, demonstrating the usefulness of metabolomics for the toxicity mechanism elucidation of emerging pollutants.

New cultivation methodology for production of “Salinispora tropica” – bacteria with great potential

Antarctic snow microbial communities are complex biomes formed by different groups of microorganisms that include algae, bacteria, fungi, and archaea. During spring-summer season, abundant microalgae generate red, orange, pink, green and even yellow patches of snow. The presence of microalgae in snow ecosystems is pivotal for carbon fixation and has the potential to decrease snow albedo. Up to now, the relationship between microorganism diversity and functionality in these ecosystems in Maritime Antarctica is not well understood. In the present study, the microbial composition of different types of colored snow was determined by metabarcoding at Fildes Peninsula, King George Island (Maritime Antarctica). Additionally, light use characteristics were assessed to gain insights into the photosynthetic functionality of different algal groups causing snow blooms. Results from this study indicated that green algae of the Trebouxiophyceae and Chlorophyceae classes dominated the eukaryotes. A high abundance of Stramenopiles was also detected. Besides these findings, Principal Component Analysis was employed, revealing taxonomic distance among sampling sites. Bacteroidetes and Proteobacteria were found to be the most abundant groups in the bacterial communities with an absence of taxonomic distance among sampling sites. However, the presence of Flavobacteria and γ-Proteobacteria varied among samples. Photosynthetic parameters determined for dominating algae within the blooms were dependent on the sites and snow colors. All in all, these results show that snow algae blooms at Fildes Peninsula represent a mixture of algal species with different light requirements.

The influence of microalgae on vegetable production and nutrient removal in greenhouse hydroponics

Abstract: The effect of microalgae on plant growth and nutrient removal was assessed for three vegetables (arugula, purple kohlrabi and lettuce) grown entirely using nitrate-rich synthetic wastewater in greenhouse hydroponics. Results showed that the response of the vegetables to microalgae varied. Microalgae had a negative effect on arugula growth, but in the purple kohlrabi and lettuce groups, there were no negative effects or even an increase in vegetable production. The dissolved oxygen (DO) and microalgae biomass concentrations in the group with microalgae added were relatively higher. pH increased because of microalgae photosynthesis and decreased due to NH3–N removal processes. The presence of microalgae, especially Chlorella vulgaris addition, can significantly improve the removal rate of total dissolved solids, total nitrogen (TN), and total phosphorus (TP), but not COD. The contribution of each vegetable and microalgal consortia on the N or P removal in greenhouse hydroponics was different. The P removal efficiency were satisfactory in all groups, especially in the natural microalgae treatment where P removal rate reached more than 98%. In some cases, vegetable hydroponics could be upgraded with microalgae co-cultivation which could be an ecofriendly and economically sustainable production system.

Aspects of the feeding biology of the copepodPseudodiaptomus hessei(Copepoda: Calanoida) under culture conditions

This study aimed to investigate the feeding behaviour (particularly gut fullness and evacuation, preying on rotifers and feeding preference in the water column) of the calanoid copepod, Pseudodiaptomus hessei, as a potential live feed species for aquaculture. Fed and starved, male and female P. hessei were fed rotifers (Brachionus plicatilis) in the presence and absence of microalgae for 24 hr. Starved copepods consumed more rotifers (11.31 ± 1.01, individual rotifers) than fed (8.06 ± 1.01, individual rotifers) while the number of rotifers consumed in the presence of microalgae was similar when fed or starved. Gut fullness and evacuation was determined by feeding copepods two different cell size microalgae species (Tetraselmis suecica and Isochrysis galbana). Gut fullness and evacuation percentage were observed under the dissecting microscope (as 0, 25, 50, 75 and 100%). Copepods fed on T. suecica (large cell) filled their guts more rapidly, while those fed on I. galbana (small cell) evacuated their guts faster. Feeding preference was determined using a multifactorial experiment where copepods were fed two microalgae species, T. suecica and I. galbana, each presented as benthic and planktonic food sources. P. hessei preferred to feed on planktonic microalgae first regardless of microalgae choice species for ±80 min, before shifting to benthic food source. This information can be used as baseline information for aquaculturists to rear the species as live feed for marine fish larvae.

INFLUENCE OF CULTIVATION OF CHLORELLA VULGARIS ON MICROORGANISMS IN SEAFOOD WASTEWATER

Microalgae cultivation in wastewater for many purposes has been investigated recently decade ago. In this study, Chlorella vulgaris was chosen to culture for examination of its influences on microorganisms of seafood wastewater in particular aerobic bacteria, Coliform and E. coli. The microalgae cultivation was realized in Erlenmeyer flasks containing seafood wastewater medium. Another was also grown in original medium called Sueoka medium for control. All experiments were set up until almost all Chlorella vulgaris decanted or flocculated in the bottom of flasks. The changes of bacteria counts including aerobic bacteria, Coliform and E. coli were measured to evaluate the impact of cultivation of Chlorella vulgaris on them in this sewage. Otherwise, the growth of microalgae has been also recorded for evaluating the effect of a new medium on metabolism of Chlorella vulgaris. The results showed that the bacteria counts were significantly reduced after day 3 of microalgae culture. These results have been calculated the efficiency of aerobic bacteria, Coliform and E. coli elimination out of wastewater medium represented approximately 70%, 81% and 90% respectively. These eliminations provided evidences of difficult metabolism of bacteria under the presence of microalgae as like as Chlorella vulgaris. In other words, the symbiosis of microalgae and bacteria in sewage could prevent the raising of bacteria counts.

Effects of Stigeoclonium nanum , a freshwater periphytic microalga on water quality in a small-scale recirculating aquaculture system

Recirculating aquaculture systems (RAS) are becoming important for aquaculture due to land and water supply limitations and due to their low environmental impact. Bacteria are important in RAS as their role in nutrient recycling has been the main mechanism for waste removal in these systems. Besides bacteria, the presence of microalgae can benefit the water quality through the absorption of inorganic nitrogen (ammonium and nitrate) and phosphorus from the water. However, reports on the inclusion of microalgae in RAS are very scarce. The objective of this study was to determine the effect of microalgae on water quality (total ammonia nitrogen, nitrite, nitrate and phosphate) and bacterial composition in a freshwater small-scale RAS. A periphytic microalga, Stigeoclonium nanum, was used in this study. A rapid fingerprint analysis, denaturing gradient gel electrophoresis (DGGE), was used to determine the bacterial community composition in the water. The results showed that ammonia concentrations were not significantly different (p > 0.05) between RAS with microalgae (RAS+A) and RAS without microalgae (RAS-A). However, nitrite, nitrate and phosphate were significantly lower in the RAS+A than the RAS-A (p 0.05); however, the bacterial composition between the treatments was significantly different (p < 0.05).

Structural effects of microalgae additives on the starch gelatinisation process

This work presents a detailed structural characterisation of the starch gelatinisation process and the effect of the addition of three microalgae species, Nannochloropsis gaditana sp., Scenedesmus almeriensis and Spirulina, by means of an advanced approach consisting of temperature-resolved simultaneous SAXS/WAXS experiments, combined with DSC. Furthermore, regular and high amylose corn starch were utilised to evaluate the impact of the amylose content.The presence of microalgae has been seen to limit water accessibility towards the interior of starch granules, reducing granule swelling and, thus, hindering the arrangement of amylopectin helices into highly ordered crystalline structures. As a result, more heterogeneous lamellar structures, with reduced apparent crystallinity, are attained. Despite the existence of lipidic compounds in the three microalgae species, the tough cell walls in Nannochloropsis and Scenedesmus impede their release towards the aqueous medium. In contrast, the weak cell walls in Spirulina are disrupted by stirring, allowing cell components to be released. The diffused lipids form helical inclusion complexes with the amylose chains and promote the crystallisation of V-type structures. The presence of amylose-lipid complexes counteracts the limited water swelling effect and results in the formation of more crystalline and homogeneous lamellar structures. This result is relevant for the food industry due to the potential of Spirulina to affect the processability and nutritional characteristics of starch-based products.

Influence of pathogenic bacterial activity on growth of Scenedesmus sp. and removal of nutrients from public market wastewater.

The present study aims to investigate the influence of Staphylococcus aureus, Escherichia coli and Enterococcus faecalis in public market wastewater on the removal of nutrients in terms of ammonium (NH4-) and orthophosphate (PO43) using Scenedesmus sp. The removal rates of NH4- and orthophosphate PO43- and batch kinetic coefficient of Scenedesmus sp. were investigated. The phycoremediation process was carried out at ambient temperature for 6 days. The results revealed that the pathogenic bacteria exhibited survival potential in the presence of microalgae but they were reduced by 3-4 log at the end of the treatment process. The specific removal rates of NH4- and PO43- have a strong relationship with initial concentration in the public market wastewater (R2 = 0.86 and 0.80, respectively). The kinetic coefficient of NH4- removal by Scenedesmus sp. was determined as k = 4.28 mg NH4- 1 log10 cell mL-1 d-1 and km = 52.01 mg L-1 (R2 = 0.94) while the coefficient of PO43- removal was noted as k = 1.09 mg NH4- 1 log10 cell mL-1 d-1 and km = 85.56 mg L-1 (R2 = 0.92). It can be concluded that Scenedesmus sp. has high competition from indigenous bacteria in the public market wastewater to remove nutrients, with a higher coefficient of removal of NH4- than PO43.

Upgrading of Al-Rustamiyah Sewage Treatment Plant Through Experimental and Theoretical Analysis of Membrane Fouling

Al-Rustamiyah plant is the oldest and biggest sewage treatment plant in Iraq; it locates in the south of Baghdad city. The plant suffers from serious problems associated with overflow and low capacity. The present work aims to upgrade the heart of biological treatment process through suggesting the use of membrane bioreactor; (MBR). In this work, fouling of membrane during sewage treatment has been analyzed experimentally and theoretically by fouling mechanisms. Aeration has been applied in order to control fouling through producing effective diameters of air bubbles close to the membrane walls. Effect of air flow rate on flux decline was investigated. Hermia's models were used to investigate the fouling mechanisms. The results showed that cake formation is the best fitted model (R2≥0.98) followed by intermediate blocking occurred with 9 L/min aeration rate. Cake layer formation is the best fit mechanism in all aeration rates (1-9 L/min) in presence of microalgae. SEM images of the membrane surface before and after filtration showed high density pores membrane surface proved a cake fouling occurring. It was found that aeration represents the most effective technique for fouling domination in addition to its important economic aspects for algae growth and propagation. An enhancement of 70.8% in flux at 9 L/min air flow has been revealed. MBR proved to be more efficient and more convenient than activated sludge since it eliminates the needing of sedimentation tanks and upgrading Al-Rustamiyah plant that has low available space for expansion.

Elimination of Antibiotic Multi-Resistant Salmonella Typhimurium from Swine Wastewater by Microalgae-Induced Antibacterial Mechanisms

The effect of microalgae-based swine waste water treatment on the removal of antibiotic multi-resistant Salmonella enterica serovar typhimurium was investigated. Photobioreactors (PBRs) containing diluted swine digestate with and without microalgae Scenedesmus spp. were inoculated with S. typhimurium (108 Colony Forming Units per milliliters - CFU mL-1). Viable cells of S. typhimurium were quantified over time by plate counts and qPCR amplification of the Salmonella invasion gene activator, hilA. In the absence of microalgae, S. typhimurium concentrations increased 1.5 log cells mL-1 in 96 h. In the presence of microalgae, S. typhimurium was completely eradicated within 48 h. In the PBRs with controlled pH (6.8 ± 0.8), concentration of S. typhimurium remained constant (2.8 ± 0.2 log CFU mL-1) throughout 96 h. Thus, natural increase in pH>10 due to photosynthesis was detrimental to the antibiotic multiresistant bacteria survival. Phycoremediation holds promises as an alternative for waste water treatment process for the elimination of the serious public health threatening antibiotic multi-resistant bacteria, thus effectively avoiding Salmonellosis outbreaks arising from animal farming activities.

ANAEROBIC CO-CULTIVATION OF MULTI-ALGAL SPECIES WITH OIL PALM EMPTY FRUIT BUNCHES FOR MILL EFFLUENT TREATMENT AND BIOMETHANE PRODUCTION

This study investigated the optimization of anaerobic co-cultivation of multi-algal species with Oil Palm Empty Fruit Bunches (OPEFB) for Palm Oil Mill Effluent (POME) treatment and biomethane production. The highest removal of COD (95-98%), BOD (90-98%), TOC (81-86%) and TN (78-80%) were achieved after 7 days anaerobic treatment with the presence of microalgae. The highest biomethane (4,651.9 mL CH4/L POME/day) and the specific biogas production rate (0.124 m3/kg COD/day) with CO2 (2,265.9mL CO2/L POME/day) were achieved by co-cultivating N. oculata and Chlorella sp. (each at 1 mL/mL POME) with OPEFB (0.12 g/mL POME). The combination of N. oculata (2 mL/mL POME) with T. suecica or Chlorella sp. (each at 1 mL/mL POME), and OPEFB (0.12 g/mL POME) obtained high biomethane (4,018.9 mL CH4/L POME /day) but lower biogas (0.097 m3/kg COD/day) and CO2 (2,079.5mL CO2/L POME/day). Generally, low OPEFB and having all the three strains or increasing the level of any (2 mL/mL POME) especially T. suecica, could lower biomethane (870-953 mL CH4/L POME/day) and CO2 (803-854mL CO2/L POME/day), with the biogas around 0.08-0.09 m3/kg COD/day. The optimum conditions were predicted by Response Surface Methodology and the multiple coefficients of determination, r2, of 86% suggests good agreement between experimental and predicted values.

Direct Effects of Microalgae and Protists on Herring (Clupea harengus) Yolk Sac Larvae.

This study investigated effects of microalgae (Rhodomonas baltica) and heterotrophic protists (Oxyrrhis marina) on the daily growth, activity, condition and feeding success of Atlantic herring (Clupea harengus) larvae from hatch, through the end of the endogenous (yolk sac) period. Yolk sac larvae were reared in the presence and absence of microplankton and, each day, groups of larvae were provided access to copepods. Larvae reared with microalgae and protists exhibited precocious (2 days earlier) and ≥ 60% increased feeding incidence on copepods compared to larvae reared in only seawater (SW). In the absence and presence of microalgae and protists, life span and growth trajectories of yolk sac larvae were similar and digestive enzyme activity (trypsin) and nutritional condition (RNA-DNA ratio) markedly declined in all larvae directly after yolk sac depletion. Thus, microplankton promoted early feeding but was not sufficient to alter life span and growth during the yolk sac phase. Given the importance of early feeding, field programs should place greater emphasis on the protozooplankton-ichthyoplankton link to better understand match-mismatch dynamics and bottom-up drivers of year class success in marine fish.

Co-pyrolysis of microalgae and waste rubber tire in supercritical ethanol

Co-pyrolysis of microalgae and waste rubber tire (WRT) in supercritical ethanol was examined to investigate the effects of reaction temperature (290–370°C), time (10–120min), WRT/microalgae mass ratio (R/M, 5/0–0:5), and ethanol/feedstock ratio (EtOH/(R+M), 5:5–30:5). Temperature and mass ratio are two factors that significantly affect the yield and quality of bio-oil. Under optimal reaction conditions, the highest bio-oil yield achieved was 65.4wt%. The presence of microalgae allows the conversion of WRT to occur under milder conditions than WRT alone. The temperature needed for adequate conversion of WRT and microalgae in supercritical ethanol (330°C) is much lower than the co-pyrolysis temperature without a solvent. ZnO and carbon black in the WRT played catalytic roles in the conversion of the WRT and microalgae as well as the in situ denitrogenation and deoxygenation of the bio-oil. A positive synergistic effect between the WRT and the microalgae was observed. The highest value for the synergistic effect (37.8%) was observed at an R/M mass ratio of 1:1. The interaction of microalgae and WRT during co-pyrolysis also favored denitrogenation and deoxygenation, thus improving the quality of the bio-oil. The heating values of the bio-oils produced from the co-pyrolysis of WRT and microalgae were found to be in the range of 35.80–42.03MJ/kg. The main components in the gas phase are typically CO2, H2, and CH4. However, methods for improving the quality of bio-oil via co-pyrolysis will require further study.

Dietary effect of fish oil and soybean lecithin on growth and survival of juvenileLitopenaeus vannameiin the presence or absence of phytoplankton in an indoor system

This study was conducted to evaluate whether phospholipids have the potential to reduce the level of dietary fish oil inclusion in shrimp feeds in the presence and absence of phytoplankton. To do so, weight gain of juvenile Litopenaeus vannamei stocked at 80 shrimp m−2 fed different dietary levels of fish oil and soybean lecithin was determined. Six experimental 35% protein diets were formulated to contain 1%, 2% or 3% fish oil combined with either 1% or 4% soybean lecithin. Dietary effects were evaluated using a ‘clear-water culture system’ without the presence of microalgae in 40-L aquaria and a ‘green-water culture system’ in 1.9-MT tanks. After an 8-week feeding period, shrimp cultured in both systems and fed diets containing 4% soybean lecithin had greater weight gain than those fed 1%. Thus, diets supplemented with phospholipids improved the efficiency of lipid utilization for growth: diets containing 1% fish oil in combination with 4% soybean lecithin can be used as a cost-effective combination for commercial shrimp culture feeds. Weight gain in the green-water system was 1.5–1.7 times greater than that for shrimp reared under clear-water conditions, suggesting that phytoplankton contributes to shrimp growth through the continuous provision of nutrients.

Dynamic approaches of mixed species biofilm formation using modern technologies

Bacteria and diatoms exist in sessile communities and develop as biofilm on all surfaces in aqueous environments. The interaction between these microorganisms in biofilm was investigated with a bacterial genus Pseudoalteromonas sp. (strain 3J6) and two benthic diatoms Amphora coffeaeformis and Cylindrotheca closterium. Each biofilm was grown for 22 days. Images from the confocal microscopy show a difference of adhesion between Pseudoalteromonas 3J6 and diatoms. Indeed, a stronger adhesion is found with C. closterium suggesting cohabitation between Pseudoalteromonas 3J6 and C. closterium compared at an adaptation for bacteria and A. coffeaeformis. The cellular attachment and the growth evolution in biofilm formation depend on each species of diatoms in the biofilm. Behaviour of microalgae in presence of bacteria demonstrates the complexity of the marine biofilm.

Effects of Endosulfan (Thiodan 35 EC®) on Meiofauna Community Through a Microcosm Approach

A microcosm experiment with natural community of meiofauna was performed to test the effects of the organochlorine pesticide Thiodan 35 EC (35% endosulfan) at concentrations more likely to reach the estuaries by the sugar cane crops runoff. A methodological proposal for microcosms was tested for tropical estuaries. The nominal concentrations (0.001, 0.005, 0.01, 0.05, 0.10, 0.20, 0.35 and 0.55 μg.g-1 + control) and experimental times (0, 1, 4, 8 and 16 days) were adopted. Nominal and measured endosulfan concentrations in Thiodan showed highly significant correlation with losses below 60%. Significant differences were detected for meiofauna structure between experimental days and concentrations tested. The organochlorine Thiodan measured as endosulfan concentrations had affected the Kinorhyncha group on Day 8 and the Simple Linear Regression explained part of densities variation. There were no significant concentration effects on microphytobenthos and its concentration was not related to groups’ feeding. Despite the moderate to high volatilization rate of the endosufan observed in the end of the experiment, it is suggested the absence of mortality patterns due to pesticide bioavailability related to both sedimentary factors and the presence of microalgae. Possible replacement of sensitive by tolerant species or predominance of resistant species in each meiofauna group throughout the experiment is another hypothesis to be discussed.

Airlift column photobioreactors for Porphyridium sp. culturing: Part I. effects of hydrodynamics and reactor geometry

Photosynthetic microorganisms have been attracting world attention for their great potential as renewable energy sources in recent years. Cost effective production in large scale, however, remains a major challenge to overcome. It is known to the field that turbulence could help improving the performance of photobioreactors due to the so-called flashing light effects. Better understanding of the multiphase fluid dynamics and the irradiance distribution inside the reactor that cause the flashing light effects, as well as quantifying their impacts on the reactor performance, thus, are crucial for successful design and scale-up of photobioreactors. In this study, a species of red marine microalgae, Porphyridium sp., was grown in three airlift column photobioreactors (i.e., draft tube column, bubble column, and split column). The physical properties of the culture medium, the local fluid dynamics and the photobioreactor performances were investigated and are reported in this part of the manuscript. Results indicate that the presence of microalgae considerably affected the local multiphase flow dynamics in the studied draft tube column. Results also show that the split column reactor works slightly better than the draft tube and the bubble columns due to the spiral flow pattern inside the reactor.

Dietary effect of squid and fish meals on growth and survival of Pacific white shrimpLitopenaeus vannameiin the presence or absence of phytoplankton in an indoor tank system

This study was conducted in 36 indoor 40-L fibreglass aquaria to determine the weight gain and survival of Litopenaeus vannamei fed different dietary levels of fish (FM) and squid meal (SM) and to evaluate the potential of phytoplankton to reduce FM and SM levels in shrimp feeds. Six experimental isonitrogenous (35% protein) and isocaloric (17.5 kJ g−1) diets were formulated to contain either 5%, 10% or 20% SM combined with either 6.5% or 12% FM. Dietary effects on growth and survival were compared in two systems: a ‘CLEAR water system’ (CWS) without the presence of microalgae and a ‘GREEN water system’ (GWS) with microalgae in the culture water. Shrimp cultured in the GWS had 28–57% greater weight gain than those cultured in the CWS, regardless of dietary treatment. However, survival was not different. Shrimp cultured in the CWS or the GWS, and fed diets containing combinations of FM and SM did not show differences in weight gain and feed conversion ratio. These results suggest that under the conditions existing during this research, 6.5% FM and 5% SM can be used as a cost-effective combination in commercial feeds for shrimp production and that growth can be enhanced in the presence of primary productivity.

Uptake of Cd(II) and Pb(II) by microalgae in presence of colloidal organic matter from wastewater treatment plant effluents

The present study addresses the key issue of linking the chemical speciation to the uptake of priority pollutants Cd(II) and Pb(II) in the wastewater treatment plant effluents, with emphasis on the role of the colloidal organic matter (EfOM). Binding of Cd(II) and Pb(II) by EfOM was examined by an ion exchange technique and flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry in parallel to bioassays with green microalga Chlorella kesslerii in ultrafiltrate (<1 kDa) and colloidal isolates (1 kDa to 0.45 μm). The uptake of Cd by C. kesslerii was consistent with the speciation analysis and measured free metal ion concentrations, while Pb uptake was much greater than that expected from the speciation measurement. Better understanding of the differences in the effects of the EfOM on Cd(II) and Pb(II) uptake required to take into account the size dependence of metal binding by EfOM.

Real-time PCR detection and quantification of fish probioticPhaeobacterstrain 27-4 and fish pathogenicVibrioin microalgae, rotifer,Artemiaand first feeding turbot (Psetta maxima) larvae

To develop a SYBR Green quantitative real-time PCR protocol enabling detection and quantification of a fish probiotic and two turbot pathogenic Vibrio spp. in microcosms. Phaeobacter 27-4, Vibrio anguillarum 90-11-287 and Vibrio splendidus DMC-1 were quantified as pure and mixed cultures and in presence of microalgae (Isochrysis galbana), rotifers (Brachionus plicatilis), Artemia nauplii or turbot (Psetta maxima) larvae by real-time PCR based on primers directed at genetic loci coding for antagonistic and virulence-related functions respectively. The optimized protocol was used to study bioencapsulation and maintenance of the probiont and pathogens in rotifers and for the detection and quantification of Phaeobacter and V. anguillarum in turbot larvae fed rotifers loaded with the different bacteria in a challenge trial. Our real-time PCR protocol is reproducible and specific. The method requires separate standard curve for each host organism and can be used to detect and quantify probiotic Phaeobacter and pathogenic Vibrio bioencapsulated in rotifers and in turbot larvae. Our method allows monitoring and quantification of a turbot larvae probiotic bacteria and turbot pathogenic vibrios in in vivo trials and will be useful tools for detecting the bacteria in industrial rearing units.