Presence Of Microalgae Research Articles

Economically viable bioprocess for inclusion of microalga Nannochloropsis gaditana in aquaculture feeds: Evaluation of antioxidant addition in preventing lipid oxidation during storage

The rising prices of fishery derivatives limits their use in aquafeeds. Therefore, other alternatives are used to replace those ingredients. Among them, microalgae are of great interest both as an ingredient and as a potential stabilising agent against lipid oxidation. This study evaluates on the use of Nannochloropsis gaditana to prevent lipid oxidation in a set of 12 aquafeeds over 540 days of storage. Aquafeeds were formulated with/without 15 % N. gaditana combined with two antioxidants −butylhydroxytoluene (25–150 mg·kg-1) or vitamin E (500–3000 mg·kg-1). The effect of i) storage period, ii) presence of microalgae and iii) antioxidant addition on lipid oxidation was assessed. Results showed higher fatty acid degradation in diets lacking microalgae. The microalgae supplemented diets is enough for preserving feeds presenting the highest antioxidant effect at the end, without significant differences with the microalgae-supplemented feeds and those including antioxidants after 540 days of storage.

STUDI KEANEKARAGAMAN MIKROALGA DI SUNGAI MARGASATWA RAGUNAN SEKITAR KANDANG BUAYA

Microalgae are microscopic unicellular organisms that have varying sizes, shapes, and types, have photosynthetic pigments, are photoautotrophic, and are found in aquatic environments. Microalgae have certain limits of tolerance to water chemical physics factors. The presence of microalgae in water can be used as an indicator of the state of the water. This study aims to identify the diversity of microalgae as an indicator of the water quality present in the river around the Ragunan Margasatwa crocodile cage. Sampling was done in the Ragunan Margasatwa Park river near the crocodile cage. Samples of macroalgae are visually identified and include morphology, color, shape, and other characteristics. Based on the observations, it can be concluded that the river ecosystems around the crocodile cages are under low ecosystem pressure. The diversity index generally has a range of values between 1.5 and 4, and lower values reflect increasing ecosystem instability. The lowest microalgae density was found at station 1, which is 120 ind/ml. Individuals with the highest density at station 2, the species Aphanothece sp. with a density value of 293.3 ind/mL.

Exploring the size-dependent dynamics of photosynthetic cells in rainwater: The influence of atmospheric variables and rain characteristics

The presence of microalgae in the atmosphere raises health and environmental concerns. Despite recent scientific advances, our knowledge of the origins and dynamics of photosynthetic cells in relation to atmospheric processes is limited due to a lack of empirical data. To address this gap, we conducted a one-year survey, collecting and analyzing rainwater samples. This study proposes to investigate the temporal dynamics of photosynthetic cells based on their size in combination with a unique dataset of variables of interest: type of rain and its characteristics, local meteorology, concentrations of inorganic chemical species, and long-range air mass transport. The analysis of the biochemical composition of rainwater, along with its correlation with the origin of air masses using ions as tracers, provides evidence of the long-range transport of photosynthetic cells. Additionally, our study reveals distinct removal mechanisms from the atmosphere for photosynthetic cells depending on their size. Our results suggest that convective events with high-intensity rainfall led to the efficient removal of medium-sized photosynthetic cells (4–15 μm) from the atmosphere. However, removal mechanisms for small (<4 μm) and large-sized cells (>15 μm) are not influenced by microphysical rainfall characteristics and seem to be governed by different atmospheric processes: dry deposition is proposed to be a significant mechanism for the removal of large-sized photosynthetic cells, while small-sized cells detected in rain are correlated with the horizontal wind speed and duration of rainfall, particularly during stratiform events. This implies that the removal of photosynthetic cells from the atmosphere is strongly influenced by environmental variables, which are expected to vary in response to global change. Therefore, it is crucial to enhance the monitoring of photosynthetic cells in relation to atmospheric processes and investigate the potential impact of the dissemination of genetic material from distant sources on recipient ecosystems.

Microalgal diversity assessment of Laguna Lake (Philippines) tributaries using Next-Generation Sequencing for water quality

Abstract. Santos JA, Mejia JA, Galarion MAJ, Vital P. 2023. Microalgal diversity assessment of Laguna Lake (Philippines) tributaries using Next-Generation Sequencing for water quality. Biodiversitas 24: 4636-4644. The species composition and density of microalgae have been successfully used as bioindicators of water quality as they respond quickly to any change in the water chemistry brought about by pollution. Laguna Lake in the Philippines, one of the country's most important hotspots for aquaculture, continues to be threatened by eutrophication, yet its microalgal profile has been understudied. The presence of microalgae, especially those identified to become causative agents of harmful algal blooms in lakes, can cause corresponding health effects in humans and the environment. This study determined microalgal diversity in samples from tributaries of Laguna Lake, Philippines, through 18S rRNA metagenomic sequencing or Next-Generation Sequencing (NGS). Out of the five sampling sites, only two sites passed the NGS quality control pipeline. Chlorella M.Beijerinck, dominated the eukaryotic microbial population in the Alabang-Cupang River sample, which is 95% of the total population. While in the Biñan River sample, relevant species found were Cyclotella scaldensis Muylaert &amp; Sabbe, Teleaulax acuta (Butcher) Hill, Cryptomonas curvata Ehrenb., and Peridiniopsis penardii (Lemmerm.) Bourr. This is the first study to use NGS to detect microalgae in Laguna Lake and warrants further elucidation of the microalgal population through increased sampling efforts in other recreational and livelihood hotspots. Furthermore, the study results open the importance of implementing new schemes for water quality assessments focused on molecular-based approaches.

Microalgae-based constructed wetland system enhances nitrogen removal and reduce carbon emissions: Performance and mechanisms

Combination of constructed wetlands (CWs) and microalgae-based technologies has been proved as effective wastewater treatment option; however, little attention was paid to investigate the optimal combination ways. This study showed that the integrated system (IS) connecting microalgal pond with CWs exhibited improved pollutant-removal efficiencies and preferred carbon reduction effects compared to other alternatives such as coupled system or independent CWs. Microbial analysis demonstrated that core microorganisms (e.g., Acinetobacter and Thermomonas) of the IS were mostly associated with carbon, nitrogen, and energy metabolism. Based on co-occurrence networks, microbial quantity with denitrification function in the IS accounted for 71.01 % of the microorganism related to nitrogen metabolism, which was higher than that of 48.84 % in the independent CWs, indicating that the presence of microalgae in IS played important role in promoting biological denitrification. These findings provide insights into the microbial mechanism and highlights the complementary effects between microalgae and CWs.

Water quality improvement using novel attached growth systems

ABSTRACT Excessive growth of microalgae results in the eutrophication and degradation of water quality in lakes and ponds. Microalgae have proved to be very beneficial for sustainable development. Its applications, starting from growth to death, make them a valuable resource for food and energy production. However, presence of microalgae in surface water sources affects water quality and its beneficial uses. The excess nutrient-rich agriculture runoff also adds problems to the downstream systems. Nutrient removal and microalgae harvesting are considered the most problematic task for improving water quality of surface waters. The main objective of the present study was to improve the water quality of nutrient rich waters using attached growth systems. The use of batch and continuous flow baffled attached growth systems has successfully improved the water quality and produced algal biomass that can be utilized or transformed into other valuable products. The performance of continuous flow baffled attached growth system was better and it improved the quality of oligotrophic, mesotrophic, eutrophic and hypereutrophic waters by removing>95% of TN and TP in 35, 63, 63 and 4 days, with biomass productivity of 2.69 ± 0.21, 3.17 ± 0.06, 3.61 ± 0.16 and 4.64 ± 0.3 gDWm−2 day−1, respectively.

Preparation of Synbiotic Yogurt Sauce Containing Spirulina platensis Microalgae Extract and Its Effect on the Viability of Lactobacillus acidophilus.

Preparing a healthy and practical substitute for mayonnaise and reducing the complications caused by its consumption are two of the concerns of the producers of this product. Therefore, this study was conducted with the aim of evaluating the possibility of producing synbiotic yogurt sauce prepared with Spirulina platensis microalgae extract (SPAE) as a valuable and alternative product for mayonnaise. After preparing yogurt from fresh cow's milk, synbiotic yogurt sauce was prepared according to the formulation, and the effect of SPAE at the rate of 0.5, 1, and 2% on the viability of the probiotic bacteria Lactobacillus acidophilus was evaluated, and chemical, rheological, and sensory tests were carried out in the storage period (35 days). The highest viability rate of L. acidophilus was related to the treatment containing 2% of SPAE with 1.31 log CFU/g reduction (from 9.02 log CFU/g on the first day to 7.71 log CFU/g on the final day) and 1% of SPAE with 2.98 log CFU/g reduction, respectively, which were significantly more effective than other treatments (P < 0.05), and it was found that the viability rate increases with the increase in the percentage of the prebiotic composition. There was also a significant difference between the treatments in the simulating conditions of the digestive system, and the viability of L. acidophilus in the treatment containing the prebiotic composition increased (P < 0.05). According to the results, during storage, in the presence of microalgae, acidity increased, and pH, viscosity, and sensory properties decreased compared to the control group. Upon analyzing the results, it was found that the addition of the prebiotic composition of SPAE, which is known as a functional product, led to a partial improvement in its properties. Therefore, the use of this alga, while benefiting from its medicinal and therapeutic properties, increases the viability rate of probiotic.

Tubular photo-MFC reactors as wastewater polishing treatment step with simultaneous electricity production

Wastewater treatment processes energy and emissions issues led researchers to investigate more sustainable alternative technologies, aimed at achieving effective contaminants removal with simultaneous resources recovery (i.e., energy). The combination of microbial fuel cell (MFC) technology with microalgal-based processes in a photo-MFC (PhMFC) could potentially reduce GHGs impact of wastewater treatment, capturing anodically produced CO2 and photosynthetically convert it into oxygen, with a bioelectrochemical, cathodic polishing step. Two tubular PhMFCs were operated with synthetic wastewater under different conditions. Organic matter and nutrients removals and electricity production were monitored under each tested condition. Energy losses and design issues were also analyzed. The two PhMFCs globally proved to be effective in COD (up to 94%), total nitrogen (55%) and total phosphorus (60%) removal, with simultaneous bioelectricity production (up to 5.5 ‧ 10−4 kWh m−3). The presence of microalgae also opens the possibility of recovery opportunities connected to the post-processing of the cathodic effluent.

Strategy for the formation of microalgae-bacteria aggregates in high-rate algal ponds

ABSTRACT This work studied the formation of aggregates used for wastewater treatment in high-rate algal ponds (HRAP). For this, the establishment of microalgae-bacteria aggregates in these systems was evaluated, considering strategies for the inoculation and start-up. Two HRAP were operated in parallel, at first in batch mode and then in continuous flow. The wastewater treatment was efficient, with removal rates around 80% for COD and N-ammoniacal. Volatile suspended solids and chlorophyll for the culture grew continuously reached a concentration of 548 ± 11 mg L−1 and 7.8 mg L−1, respectively. Larger photogranules were observed when the system was placed in a continuous regime. The protein fraction of extracellular polymeric substances was identified as a determinant in photogranules formation. During the continuous regime, more than 50% of the biomass was higher than 0.2 mm, flocculation efficiency of 78 ± 6%, and the volumetric sludge index of 32 ± 5 mL g−1. The genetic sequencing showed the growth of cyanobacteria in the aggregate and the presence of microalgae from the chlorophytes and diatoms groups in the final biomass.

Cell growth and removal capacity of ibuprofen and diclofenac by Parachlorella kessleri at bench scale

AbstractBACKGROUNDThe presence of pharmaceutical compounds has been studied in several countries in Latin America, and many xenobiotic compounds have been identified in wastewater, surface water and even drinking water, including ibuprofen and diclofenac. Microalgal‐based systems have been identified as a good alternative for removing these micropollutants, particularly under tropical conditions, and they are associated with low operational cost and high removal efficiency. Although studies for removing pharmaceutical compounds with Parachlorella kessleri are scarce, this microalga has demonstrated good performance in the treatment of wastewater.RESULTSUsing doses of ibuprofen of 1000 and 16 000 μg L−1 and of diclofenac of 100 and 500 μg L−1, the removal efficiency of P. kessleri was evaluated under controlled conditions for periods of 12, 48 and 96 h during cell growth. A hormesis process was identified after an alarm phase at the first 12 h and a recovery at 48 h for ibuprofen, because the diclofenac curve achieved an early death phase, which was associated with oxidative damage. Total removal of up to 51.3% and 55.7% was obtained for ibuprofen and diclofenac, respectively. These removal efficiencies were mostly influenced by microalgae by the process of bioaccumulation/adsorption (23.3% for ibuprofen and 37.1% for diclofenac) and by other mechanisms (40.6% for ibuprofen and 44% for diclofenac).CONCLUSIONRemoval efficiencies were mainly associated with the presence of microalgae and removal mechanisms such as bioaccumulation and biodegradation for diclofenac, and biodegradation for ibuprofen. © 2021 Society of Chemical Industry (SCI).

Estuarine benthic nitrate reduction rates: Potential role of microalgae?

The ecological functioning of the Seine estuary is strongly affected by the input of nitrogen, especially in the form of nitrate, which contributes to the eutrophication of the Seine Bight (France). Elimination of nitrate by benthic denitrification in riparian zones or adjacent wetlands could significantly improve the water quality of the Seine estuary. The goal of this study was to investigate the potential for denitrification and the factors affecting these rates. To this end, we measured nitrate reduction and ammonium production rates using flow-through reactors in contrasted sediments collected along the Seine Estuary. Sediment and organic carbon characteristics (organic C, Corg:N ratio, bioavailable carbon, extracellular polymeric substances (EPS), chlorophyll a and phaeopigments and abundance of nitrogen transforming microorganisms were determined and related to the potential nitrate reduction rates. Nitrate reduction rates showed a large spatial and seasonal variation and showed a significant correlation with sediment phaeopigments, whereas overall microbial activity (ammonium production rates) were highly correlated to chlorophyll a and EPS fractions. Surprisingly, bacterial abundance was not correlated to nitrate reduction nor to ammonium production rates. The presence of microalgae appears to be an important driver for nitrate reduction rates in these riparian sediments and seems to have fueled the benthic nitrate reducing activity.

Design, Commissioning, and Performance Assessment of a Lab-Scale Bubble Column Reactor for Photosynthetic Biogas Upgrading with Spirulina platensis.

The two-step bubble column-photobioreactor photosynthetic biogas upgrading system can enable simultaneous production of biomethane and value-added products from microalgae. However, due to the influence of a large number of variables, including downstream processes and the presence of microalgae, no unanimity has been reached regarding the performance of bubble column reactors in photosynthetic biogas upgrading. To investigate this further, the present work documents in detail, the design and commissioning of a lab-scale bubble column reactor capable of treating up to 16.3 L/h of biogas while being scalable. The performance of the bubble column was assessed at a pH of 9.35 with different algal densities of Spirulina platensis at 20 °C in the presence of light (3–5 klux or 40.5–67.5 μmol m–2 s–1). A liquid/gas flow (L/G) ratio of 0.5 allowed consistent CO2 removal of over 98% irrespective of the algal density or its photosynthetic activity. For lower concentrations of algae, the volumetric O2 concentration in the upgraded biomethane varied between 0.05 and 0.52%, thus providing grid quality biomethane. However, for higher algal concentrations, increased oxygen content in the upgraded biomethane due to both enhanced O2 stripping and the photosynthetic activity of the microalgae as well as clogging and foaming posed severe operational challenges.

Organic Substances Reduction in Palm Oil Mill Effluent (POME) After Cultivation with Locally Isolated Microalgae

This work aims to study the ability of locally isolated microalgae to reduce organic substances in Palm Oil Mill Effluent (POME) which was carried out on a laboratory scale. Inoculum with a concentration of 20% was cultivated into POME media with various concentration of LP100 (without dilution), LP75 (25% dilution), and LP50 (50% dilution) using aeration and continuous lighting for 15 days in vessels with a lighting intensity of 1300 lux. Biomass of microalgae were observed daily and analyzed in dry weight by means of spectrophotometry using 624 nm wavelength to get their growth by determining the content of algae biomass. The reduction of organic substances in POME was observed by measuring the COD, BOD phosphate, ammonium, nitrate, and fatty oil parameters every 3 hours with the standard method. Results show that the growth of microalgae occurred well in POME media at LP75 and LP50 concentrations with inoculum concentration of 20% under 1300 lux lighting intensity conditions with a continuous 24-hour lighting and aeration cycle that obtained biomass content of 0.92 and 1.08 g-DW/L, respectively. The presence of microalgae in POME at concentration of LP75 for 12 days reduced organic substances and nutrients reaching 80.74% - 99.70%. Some parameters that were reduced include BOD (99.35%), COD (89.57%), TSS (89.68%), Phosphate (97.70%), Ammonium (95.08%), Fatty Oil (99.70%), and Nitrates (80.74%). This study concludes that locally isolated microalgae have ability to treat POME safely for environment and as a growing medium for microalgae followed by a decrease in organic substances.

Capture of conspecific planktonic larvae by the suspension-feeding gastropodCrepipatella peruviana: association between adult and larval size

ABSTRACTFree-living, planktonic larvae can be vulnerable to capture and ingestion by adult suspension-feeders. This is particularly the case for larvae that settle gregariously in benthic environments where suspension-feeders occur at high densities. Larvae of gregarious suspension-feeding species are at particularly high risk, as adults of their own species often serve as cues for metamorphosis. We conducted laboratory experiments to assess the extent to which adults of the suspension-feeding caenogastropod Crepipatella peruviana would capture and ingest their own larvae. Experiments were conducted with adults of different sizes, with larvae of different ages and sizes, and in the presence or absence of phytoplankton. Adults captured larvae in all experiments. The presence of microalgae in the water did not influence the extent of larval capture. On average, 39% of larvae were captured during the 3-h feeding periods, regardless of adult size. However, up to 34% of the larvae that were captured on the gill were later discarded as pseudofaeces; the other 64% were ingested. The extent of capture by adults was not related to adult size, or to larval size and, thus, to larval age. Our results suggest that the filtration of congeneric larvae by adult C. peruviana is a result of accidental capture rather than a deliberate feeding preference. Such ingestion could, however, still be an important source of larval mortality, especially when the advanced larvae of this species are searching for a suitable substrate for metamorphosis.

Dynamics and productivity of microalgae in presence of predators

Abstract This paper is concerned with the dynamics and the productivity of biomass in a continuous microalgae culture contaminated by predators. We propose a general model describing a cultivation system where photolimited microalgae are grazed by zooplankton. We state necessary and sufficient conditions for the existence of a coexistence equilibrium. If this equilibrium exists, then microalgae and predators converge either to it or to a globally asymptotically stable periodic solution. In absence of the coexistence equilibrium, any solution approaches either an equilibrium characterized by the presence of algae and the absence of predators, or the washout equilibrium. This description of the dynamics allows to define the microalgae productivity in the long-term (i.e. when an attracting set is reached). With the help of numerical simulations, we show that operating the system at optimal (constant) dilution rate triggers the extinction of predators.

Mixed culture microalgae removal for water quality improvement using chitosan

The presence of microalgae affects water quality and beneficial uses of surface freshwaters. Chitosan with proven potential for harvesting specific microalgae species from their culture medium to produce biofuels and bioproducts also appears promising for efficient removal of mixed microalgae species from surface freshwaters. The main focus of the present study was on removal of mixed microalgae species using chitosan as a coagulant to help improve water quality. Important operational parameters were optimized for economical microalgae removal. The microalgae cells, chlorophyll-a, total nitrogen, and total phosphorous removal efficiency were 82.06%, 89.90%, 69.32%, and 44.01%, respectively, at an optimum chitosan dose of 10 mg/L, pH 8, slow mixing time 7 min, slow mixing rate 30 rpm, and settling time of 15 min. The results show that chitosan coagulation efficiently removed mixed microalgae species from surface freshwater with significant improvement in water quality and recovery of algal biomass for other beneficial applications.

Treatment of fizzy drink factory wastewaters by microalgae and evaluation of algae oil for biofuel production

As a result of city, industrial and agricultural activities, a large amount of wastewater is generated every year. The wastewater generated must be treated. When the nitrogen concentration in wastewater reaches more than 1.9 mg / L, favorable environmental conditions are provided for the microalgae to multiply. In the presence of microalgae in wastewater treatment technologies, treatment has gained importance in recent years and has become a more environmentally-friendly alternative in treatment. Research on the availability of biomass as a source of raw materials in the production of alternative energy sources is increasingly important. In this paper, Chlorella variabilis microalgae growth, lipid productivity and nutrient removal in wastewater media were investigated. Before inoculation of microalgae, wastewater was centrifuged at 4000 rpm to remove the solid particles and was diluted with tap water in different ratios (0-40%). Wastewaters were inoculated with Chlorella variabilis in 250 mL open flasks in a 200 rpm shaking incubator for a month at 27 °C. After incubation maximum cell concentration (Xmax=1.03 gdw/L), growth rate (µmax=4.0 x10-3), doubling time (173 h) of the microalgae were reached in 40% diluted medium. Fat content (21%) and lipid productivity (6x10-3 g/L.d) were determined concurrently for 20% diluted media. It was determined that microalgae lipids were rich in oleic (C18:1 38%) and linolenic acid (C18:3 35%). The efficiency of COD (Chemical oxygen demand) and total phosphor removal in the presence of microalgae had been almost 60% and 77% respectively. According to the experimental results, the treatment of wastewater in the presence of microalgae is promising for future applications.

Dynamics of the periodically forced light-limited Droop model

The periodically forced light-limited Droop model represents microalgae growth under co-limitation by light and a single substrate, accounting for periodic fluctuations of factors such as light and temperature. In this paper, we describe the global dynamics of this model, considering general monotone growth and uptake rate functions. Our main result gives necessary and sufficient conditions for the existence of a positive periodic solution (i.e. a periodic solution characterized by the presence of microalgae) which is globally attractive. In our approach, we reduce the model to a cooperative planar periodic system. Using results on periodic Kolmogorov equations and on monotone sub-homogeneous dynamical systems, we describe the global dynamics of the reduced system. Then, using the theory of asymptotically periodic semiflows, we extend the results on the reduced system to the original model. To illustrate the applicability of the main result, we include an example considering a standard microalgae population model.

Modeling and Analysis of an Absorption Column Connected to a Microalgae Culture

We build and analyze a mathematical model of a system for biogas upgrading: an absorption column connected to a microalgae culture. The construction of the model is based on a chemical engineering approach and classical models of microalgae cultures. In our analysis, we prove the existence and uniqueness of solutions of a boundary value problem describing the absorption column. Some properties of this solution are also proved. Then, we use these results to study the long-term behavior of the mathematical model describing the coupled system. We state sufficient conditions for the existence of a globally attracting steady state characterized by the presence of microalgae. Finally, we find numerically the steady states of the system to test the efficiency of the system for purifying biogas.

Microbial composition and photosynthesis in Antarctic snow algae communities: Integrating metabarcoding and pulse amplitude modulation fluorometry

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.