Effects Of Microalgae Research Articles

Effect of microalgae and bacteria inoculation on the startup of bioreactors for paper pulp wastewater and biofuel production

The use of microalgae and bacteria as a strategy for the startup of bioreactors for the treatment of industrial wastewater can be a sustainable and economically viable alternative. This technology model provides satisfactory results in the nitrification and denitrification process for nitrogen removal, organic matter removal, biomass growth, sedimentation, and byproducts recovery for added-value product production. The objective of this work was to evaluate the performance of microalgae and bacteria in their symbiotic process when used in the treatment of paper pulp industry wastewater. The experiment, lasting fourteen days, utilized four bioreactors with varying concentrations in mgVSS/L of microalgae to bacteria ratio (R1-100:100, R2-100:300, R3-100:500, R4-300:100) in the startup process. Regarding the sludge volumetric index (SVI), the results show that the R1 and R2 reactors developed SVI30/SVI10 biomass in the range of 85.57 ± 7.33% and 84.72 ± 8.19%, respectively. The lipid content in the biomass of reactors R1, R2, R3 e R4 was 13%, 7%, 19%, and 22%, respectively. This high oil content at the end of the batch, may be related to the nutritional stress that the species underwent during this feeding regime. In terms of chlorophyll, the bioreactor with an initial inoculation of 100:100 showed better symbiotic growth of microalgae and bacteria, allowing exponential growth of microalgae. The total chlorophyll value for this bioreactor was 801.46 ± 196.96 μg/L. Biological removal of nitrogen from wastewater from the paper pulp industry is a challenge due to the characteristics of the effluent, but the four reactors operated in a single batch obtained good nitrogen removal. Ammonia nitrogen removal performances were 91.55 ± 9.99%, 72.13 ± 19.18%, 64.04 ± 21.34%, and 86.15 ± 30.10% in R1, R2, R3, and R4, respectively.

The effects of microalgae use as a biofertilizer on soil and plant before and after its anaerobic (co-)digestion with food waste

The increase in food waste generation has resulted in significant challenges for its sustainable management. Anaerobic digestion coupled with microalgae-based ponds for digestate treatment can be used as a low-cost eco-friendly technology approach. In this case, microalgal biomass harvested from the ponds may be valorized into bioenergy (biogas) and soil conditioner and/or biofertilizers. The aim of the present study was to evaluate the microalgal biomass produced from a food waste digestate treatment ponds as agricultural fertilizer. For this purpose, microalgal biomass was tested before and after anaerobic digestion and co-digestion with food waste, exploring its potential for valorization. The inorganic fertilizer urea and soil with no fertilization were also used as treatments. The experimental design consisted of applying the treatments in pots cultivated with hybrid grass Brachiaria cv. Sabiá and distributed in randomized blocks in a controlled greenhouse. Microalgal biomass was mainly composed by Scenedesmus sp.. The assessed parameters showed comparable results on plant growth (i.e. number of tillers, fresh and dry matter and Chlorophyll content index) for fresh and digested microalgal biomass and inorganic fertilizer. Furthermore, it was observed that fresh microalgae provided the highest Phosphorus content in the leaf (21 %). Additionally, there were increases of 9 % in Nitrogen and 12 % in organic matter in the soil after applying digested microalgae compared to the control group without any fertilization. Finally, experimental data obtained suggests that microalgae-based biofertilizer holds the potential to replace inorganic fertilizer as a nutrient source. Moreover, it contributes to the valorization of by-products from organic waste treatment.

Chemotactic Interactions of Scenedesmus sp. and Azospirillum brasilense Investigated by Microfluidic Methods

The use of algae for industrial, biotechnological, and agricultural purposes is spreading globally. Scenedesmus species can play an essential role in the food industry and agriculture due to their favorable nutrient content and plant-stimulating properties. Previous research and the development of Scenedesmus-based foliar fertilizers raised several questions about the effectiveness of large-scale algal cultivation and the potential effects of algae on associative rhizobacteria. In the microbiological practice applied in agriculture, bacteria from the genus Azospirillum are one of the most studied plant growth-promoting, associative, nitrogen-fixing bacteria. Co-cultivation with Azospirillum species may be a new way of optimizing Scenedesmus culturing, but the functioning of the co-culture system still needs to be fully understood. It is known that Azospirillum brasilense can produce indole-3-acetic acid, which could stimulate algae growth as a plant hormone. However, the effect of microalgae on Azospirillum bacteria is unclear. In this study, we investigated the behavior of Azospirillum brasilense bacteria in the vicinity of Scenedesmus sp. or its supernatant using a microfluidic device consisting of physically separated but chemically coupled microchambers. Following the spatial distribution of bacteria within the device, we detected a positive chemotactic response toward the microalgae culture. To identify the metabolites responsible for this behavior, we tested the chemoeffector potential of citric acid and oxaloacetic acid, which, according to our HPLC analysis, were present in the algae supernatant in 0.074 mg/ml and 0.116 mg/ml concentrations, respectively. We found that oxaloacetic acid acts as a chemoattractant for Azospirillum brasilense.

Effects of microalgae and stocking density on growth and survival rate of giant clam (Tridacna squamosa Lamarck, 1819) larvae

The present study aimed to evaluate the impact of microalgae mixture and stocking density on growth and survival rate of giant clam (Tridacna squamosa) at the veliger stage. In the first experiment, giant clam larvae of the D-stage were reared in the conical fiberglass tanks and fed with combinations of microalgae, including Chaetoceros muelleri and Isochrysis galbana (1:1), and C. muelleri, I. galbana and Nannochloropsis oculata, (1:1:1). One group of giant clam larvae without feeding was used as a control. The experiment was lasted for 7 days, until the Pediveliger stage with six replicate tanks. In the second experiment, the larvae (1 day post hatched, DPH) were reared at densities of 3, 5, 7 and 9 larvae mL-1 (so-called D3, D5, D7 and D9, respectively) for a period of 7 days. Each density was randomly assigned to 6 replicate tanks. The larvae were fed once a day with a mixture of C. muelleri, I. galbana and N. oculata, (5,000 cells/ml each type of algae). At 4DPH, extracted zooxanthelle (Symbiodinium microadriaticum) was seeded into the giant clam larvae at the concentration of 5,000cells/ml once a day.The results showed that larvae fed with C. muelleri, I. galbana and N. oculata (1:1:1) obtained the largest shell length (217.5 ± 3.1 µm), specific growth rate (SGR) 7.18 ± 0.34 (mean±SD) and the survival rate (31.5% ± 1.6%) (P<0,05). In addition, rearing densities significantly affected growth in shell length, SGR and survival rate in giant clam larvae. Of which, the larvae at D3 gained the highest shell length, SGR and survival rate. Meanwhile, the larvae at D9 had the lowest shell length, SGR and survival rate. There was no significant difference in larval survival rate between D3 and D5. Therefore, it is suggested that in the hatchery giant clam larvae reared at 5 larvae mL-1 in order to improve productivity.

Effects of microalgae, with or without xylanase supplementation, on serum immunoglobulins, cecal short-chain fatty acids, microbial diversity, and metabolic pathways of broiler chickens

Modern broilers are highly susceptible to environmental and pathogenic threats, leading to gut disorders and poor nutrient utilization if not managed properly. Nutritional programming using several feedstuffs and coproducts to manage gut health has been studied. This study used microalgae as a functional compound and xylanase enzyme in broilers' diets as a strategy to manage gut health. A total of 162 one-day-old unsexed Cobb 500 broiler chicks were randomly assigned to 1 of the 3 dietary treatments: a) corn-soybean meal-based control diet (CON), b) 3% microalgae (MAG), and c) MAG with xylanase enzyme (MAG+XYN). The chicks were reared for 35 days (d) on a floor pen system maintaining standard environment conditions to evaluate the effects of microalgae, with or without xylanase supplementation, on serum immunoglobulins, cecal short-chain fatty acids (SCFA) production, cecal microbial diversity, and metabolic pathways. No significant differences were found for serum immunoglobulin and cecal SCFA among the treatment groups (P > 0.05). Relative microbial abundance at the genus level showed that MAG and MAG+XYN groups had a diverse microbial community on d 3 and d 35. However, no bacterial genus had a significant difference (P > 0.05) in their relative abundance on d 3, but 16 genera showed significant differences (P < 0.05) in their relative abundance among the dietary treatments on d 35. Most of these bacteria were SCFA-producing bacteria. Moreover, MAG and MAG+XYN-fed broilers had better responses than CON groups for metabolic pathways (D-mannose degradation, pectin degradation I and II, β-1-4-mannan degradation, tetrahydrofolate biosynthesis, glutathione biosynthesis, glutathione-peroxide redox reactions, lactate fermentation to propionate, acetate, and hydrogen, etc.) both on d 3 and d 35. The results suggest that using microalgae, with or without xylanase, had no statistical impact on serum immunoglobulins and cecal SCFA production in broilers. However, an improvement in the cecal microbial diversity and metabolic pathways, which are essential indicators of gut health and nutrient utilization, was observed. Most of the improved metabolic pathways were related to fiber utilization and oxidative stress reduction.

Utilization of microalgae [Chlorella vulgaris Beyerinck (Beijerinck)] on plant growth and nutrient uptake of garden cress (Lepidium sativum L.) grown in different fertilizer applications

This study was employed as a pot experiment in the controlled greenhouse conditions in order to investigate the effect of microalgae [Chlorella vulgaris Beyerinck (Beijerinck)] application on plant growth and nutrient uptake of garden cress (Lepidium sativum L.) grown in different doses of mineral fertilizer applications. Sieved soil in 3-liter pots was used as the growing medium. Equal amount of irrigation was applied to all pots during the period from seed sowing to the end of the experiment. Microalgae application was applied twice (100 ml and 150 ml per pot) to the seedling-growing medium. As chemical fertilizer, 0%, 50% and 100% of NPK (160 mg N kg-1, 80 mg P2O5 kg-1, and 100 mg K2O kg-1) were applied. As the parameters in garden cress, shoot height, shoot fresh weight, total soluble content (TSS), chlorophyll amount (SPAD value) and some nutrients element (K, Ca, Fe, Zn, Cu and Mn) contents were examined. At the end of the study, microalgae applications were found to have a promising effect on plant growth and some nutrient uptake. It was observed that the values of the studied traits generally increased in the microalgae application compared to the control group.

Enhancement effects of microalgae against heavy metals-induced toxicity in Oreochromis niloticus fish with emphasis on hematological, immunological and histological aspects

Enhancement effects of microalgae against heavy metals-induced toxicity in Oreochromis niloticus fish with emphasis on hematological, immunological and histological aspects

Biofertilizing Effects of Anabaena cylindrica Biomass on the Growth and Nitrogen Uptake of Wheat

ABSTRACT There are a substantial number of studies on the biofertilization effects of cyanobacteria in rice paddy fields, mainly attributed to biological fixation of N2, but not much attention has been given to their fertilizing capacity in aerobic soils. Few studies have used solid media (i.e. a soil) when testing the plant-growth-promoting effects of microalgae on plants, and particularly on wheat. The purpose of this study was to test the biofertilizing effect of a filamentous cyanobacterium, previously isolated from an agricultural soil, in order to evaluate the potential substitution of chemical fertilizers and to test its phyto-stimulating capacity. Seedlings of Triticum aestivum were grown in pots with a peat-vermiculite mixture (1:1 weight basis) in an experiment designed as a complete randomized block, consisting of four treatments and with four replicates each: a pure culture of Anabaena cylindrica concentrated by centrifugation to 2 g dry matter L−1 (treatment B); spent cyanobacteria growth medium filtered at 0.22 µm (treatment F); harvested cyanobacterial mat re-suspended in distilled water (treatment WB); and distilled water as a control (treatment W). Aboveground wheat plant mass was improved by 40% in both treatments with cyanobacterial biomass (B and WB), as compared to the control (W) and filtrate (F), demonstrating that the co-cultivation with living cyanobacterial biomass was key to plant improvement. Chlorophyll contents were also increased by nearly 50% and nitrogen by over 10% in the treatment WB, clearly indicating that nutrients in the filtrate were irrelevant to the beneficial effects on plant growth.

Effects of microalgae -ethanol-methanol-diesel blends on the spray characteristics and emissions of a diesel engine

Effects of microalgae -ethanol-methanol-diesel blends on the spray characteristics and emissions of a diesel engine

Research Progress on The Effects of Salt Stress on Photosynthesis and Lipids of Microalgae

High salinity, temperature, light intensity, and cold environment are generally sensitive to higher plants. These pressures are a challenging environmental stress for plant growth and distribution. High salinity is an environmental stress for organisms to overcome. Due to their attractive properties, microalgae are important freshwater algae, widely used for human and animal, food source and industrial applications. This review summaries the progress&nbsp;on the effects of microalgae&rsquo;s photosynthesis and lipid content by&nbsp;salinity. At the same time, the application value of microalgae is briefly summarized.

Effect of the Lipid Fraction of Microalgae on Biochemical Parameters in Female C57BL/6 Mice

We studied the effect of microalgae of various systematic groups added to the ration on the biochemical parameters of blood serum and liver and kidney tissue in rats. It was found that microalgae had different effects on the levels of proteins, lipids, and sex hormones, activity of aminotransaminases, and filtration capacity of the kidneys. Microalgae also affected the biochemical parameters of the liver and kidney tissues.

Using Microalgae as a Sustainable Feed Resource to Enhance Quality and Nutritional Value of Pork and Poultry Meat.

Cereal grains and soybean meal are the main feedstuffs used in swine and poultry feeding, two of the most consumed meats and of key relevance to food security worldwide. Such crops are grown mostly in North and South America and transported over large distances creating sustainability concerns and, furthermore, are in direct competition with human nutrition. Alternatives to these ingredients are, thus, a pressing need to ensure the sustainability of swine and poultry production. Microalgae seem to be a viable alternative due to their interesting nutritional composition. The use of different microalgae in monogastric feeding has been addressed by different researchers over the last decade, particularly their use as a supplement, whilst their use as a feed ingredient has been comparatively less studied. In addition, the high production costs of microalgae are a barrier and prevent higher dietary inclusion. Studies on the effect of microalgae on meat quality refer mostly to fatty acid composition, using these either as a functional ingredient or as a feedstuff. Within such a context and in line with such a rationale, in this review we address the current research on the topic of the use of microalgae in poultry and swine nutrition, particularly aspects concerning pork and poultry meat quality and nutritional traits.

Potential to resist biological contamination in marine microalgae culture: Effect of extracellular substances of Nannochloropsis oceanica on population growth of Euplotes vannus and other protozoa

The commercially important marine microalgae Nannochloropsis oceanica is easily ingested by protozoan predators during large-scale cultivation. However, investigations into the effect of microalgae on the growth of protozoa are scant. A feeding experiment was conducted with Euplotes vannus grazing on different concentrations of N. oceanica. The ciliate population was significantly lower in the high concentration of algae than that in the low or medium algal concentration treatments. The density of ciliates cultured in algae filtrate media was significantly lower than that in lysate media and the blank control. Furthermore, the algal cell filtrate was added to three other protozoan populations, and they all gradually lost their ability to move and their body shape changed. This study investigated the interactions between N. oceanica and protozoan predators and provides insight on using microalgal extracellular substances to control biological contamination in the future.

Role of dietary Schizochytrium sp. in improving disease resistance of zebrafish through metabolic and microbial analysis

Schizochytrium sp. added to the diet is beneficial to improve growth and fatty acid profile of fish, but there is a lack of comprehensive understanding of the mechanism by which Schizochytrium sp. supplementation produces pathogen resistance. In the present study, the effects of dietary Schizochytrium sp. on the metabolic and intestinal microbial responses, and the intestinal histological structure were investigated in zebrafish. Three experimental diets containing different concentrations of Schizochytrium sp. (0, 60, and 120 g/kg, respectively) were formulated to feed zebrafish for 56 days. The challenge trial with the fish pathogen (Edwardsiella piscicida) showed that a diet with 120 g/kg Schizochytrium sp. significantly increased the survival rate of zebrafish. Additionally, the highest goblet cell density in the intestinal wall was observed in zebrafish fed with 120 g/kg Schizochytrium sp. Metabolomic analysis of humoral fluids indicated that the diet supplemented with Schizochytrium sp. boosted the TCA cycle, energy supply, taurine metabolism, and L-serine metabolism, whereas cholesterol metabolism decreased in zebrafish. The microbiome analysis revealed that a 120 g/kg Schizochytrium sp. supplemented diet could remarkably increase the abundance of beneficial bacteria (i.e., Lactobacillus, Dorea, Butyricicoccus, and Pseudoxanthomonas), and reduce several potential pathogens (i.e., Flavobacterium, Pseudomonas, Citrobacter, and Mycoplasmas). Combined omics analysis indicated that Dorea and Butyricicoccus species were related to the disease resistance in fish. The results of dual-omics analysis also revealed that Schizochytrium sp. had the potential to improve some metabolism related to immune function and intestinal health, thus enhancing the disease resistance of zebrafish. Our research provides a novel insight into the effect of microalgae on disease resistance in aquatic animals. Moreover, this investigation sheds substantial light on immune system processes in zebrafish and identifies candidate probiotic bacteria with immunomodulatory properties.

Mikroalglerin Antiviral Etkileri

Biyologlar tarafından fitoplankton adı da verilen mikroalgler köksüz, sapsız ve yapraksız 1-50 mikrometre çapında çok küçük bitki benzeri organizmalardır. Tatlı sularda ve denizlerde yüzbinlerce türü bulunan mikroalgler sucul ekosistemlerde besin zincirinin en alt halkasını oluştururlar. Klorofil içeren çoğu türler, enerji kaynağı olarak güneş ışığını kullanarak karbondioksidi biyomasa (biyokütle) dönüştürürler. Fotosentez prosesindeki rollerinden dolayı, atmosferdeki oksijenin büyük bir kısmını mikroalgler üretirler. Çok geniş bir biyoçeşitliliğe sahip olup, 200 binden fazla tür içerdikleri bildirilmektedir. Genetik analizler sonucu mikroalg türlerinde devamlı bir artış gözlenmektedir. Son yıllarda alglerden 15 binden fazla yeni kimyasal bileşik keşfedilmiştir. Mikroalglerden elde edilen biyobileşiklerin birçoğunun antiviral etkiye sahip olduğu gözlenmiştir. Bununla beraber bu biyoaktif bileşiklerin antibakteriyal, antioksidan ve antifungal etkileri üzerinde çok kapsamlı araştırmalar yapılmış olmasına rağmen antiviral etkileri üzerindeki araştırmalar sınırlı sayıdadır. Mikroaglerin antiviral etkileri üzerinde sınırlı sayıdaki bu araştırmalarda alglerden izole edilen bazı biyobileşiklerin “HIV, SARS ve AIDS” gibi hastalıkların etmeni olan virüslere etkili olabileceği bildirilmiştir. Ancak, mikroaglerden izole edilen farklı biyobileşiklerin koronavirüs gibi günümüzün en büyük pandemisine yol açan virüslerle ilgili araştırma sayısı yok denecek kadar azdır. Bugüne kadar KOVID-19 virüsüne karşı etkili olabilecek bir aşı veya virüsün üremesini inhibe edebilecek bir ilaç bulunamamıştır. Bu küresel sağlık sorununun çözümünde mikro veya makroalglerin ümit verici önemli doğal kaynaklardan biri olabileceği düşünülmektedir. Bu derlemede özellikle mikroalglerin antiviral etkileri özetlenmeye çalışılmış ve ülkemiz bilim insanlarının yeni antiviral ilaçların geliştirilmesinde alglerin ümit verici doğal kaynaklar olabileceği vurgulanmaya çalışılmıştır.

The effects of microalgae (Spirulina platensis and Chlorella vulgaris) extracts on the quality of vacuum packaged sardine during chilled storage

The influence of water extracts of Spirulina platensis and Chlorella vulgaris (1%) on sensory, chemical and microbiological changes was investigated in vacuum packaged sardine fillets at 4 ± 1 °C for 15 days. Mineral content and bioactive chemical components of microalgae samples were also detected by ICP-MS and GC–MS, respectively. The results showed that S. platensis and C. vulgaris were rich in mineral. Main components in the extracts of C. vulgaris and S. platensis were 3,5-dichloro-6- nitrocholestane (31.74%) and dioctylamine (67.64%), respectively. The extracts prolonged sensorial shelf life of sardine for 3 days although S. platensis group was more preffered than C. vulgaris. These microalgae extracts delayed lipid oxidation and inhibited bacterial growth apart from Gram-positive lactic acid bacteria in sardine meat. The study result revelaed that both extracts can be used as antioxidant and antimicrobial additives to maintain sensory characteristic of sardine fish.

Microalgal–Bacterial Synergistic Interactions and Their Potential Influence in Wastewater Treatment: a Review

Microalgae, as the most promising raw material for biodiesel, can absorb and transform N, P, and organic matter in wastewater into cell components such as oil, carbohydrate, and protein. The cultivation of microalgae in wastewater provides the possibility to realize harmless treatment and resource utilization of wastewater and reduce the cost of microalgal culture. Whether in a single microalgal culture process or wastewater system, there always be a large number of bacteria interacting with microalgae, forming a complex microecological system. Although microalgal–bacterial coculture system is feasible features for the higher biomass production and better nutrient adaptability from wastewater, the precise understanding of interaction and coexistence in water bodies is still unclear. Some major challenges are to develop sustainability in the microalgal–bacterial coculture system due to the incomplete knowledge about the mechanism of communication, algal growth promotion, and effect of microalgae on the indigenous bacteria in wastewater. In the present review, nutritional interaction and signal transduction, two main interaction models of algae and bacteria, and the effect of synergism of these two models on microalgal system are summarized. Moreover, the impact of algal–bacterial coculture on algal growth and removal of pollutants in wastewater treatment process was expounded systematically to develop highly efficient consortium systems by covering the sustainability limitations. This work would provide guidance for the establishment of efficient algal–bacterial symbiosis system in the wastewater with complex microecology and nutrient environment to improve the accumulation of microalgal biomass and reduce the cost of microalgal culture.

Effect of microalgae, tyre pyrolysis oil and Jatropha biodiesel enriched with diesel fuel on performance and emission characteristics of CI engine

The objective of present paper, the exhaust emission parameters blend of Jatropha, tyre pyrolysis oil and spirulina microalgae biodiesel diesel engine with a rated power of 3.5 kW at 1500 rpm. The engine was operated at constant compression ratio of 17.5 with different engine loads were applied. Comparative parameters measures of brake thermal efficiency (BTE), fuel consumption, exhaust temperature, sauter mean diameter, smoke emission, particulate matter (PM), oxides of nitrogen (NOX) and carbon dioxide (CO2) have been presented. The secondary blends (JMETPO20, SP20) meaningfully reduction in smoke, PM and NOX emissions from the diesel engine, while the improved CO2 emissions. The result shows reduction in smoke, PM and NOX emission was observed with 20% blends. Reduction in smoke emission by 11.58%, 18.33%, PM emission by 5.3%, 33.1% and NOX emission by 10.2%, 10.66% but CO2 emission slightly higher for JMETPO20 (80% JME + 20% TPO) and SP20 (80% diesel + 20% spirulina) respectively at full load condition. Numerical and experimental results are valid for diesel engines of conventional diesel fuel, using 220 bar fuel injection pressure. Validation work is performed through the proposed numerical solver using experimental results.

Insights into identifying the effect of harmful algae on ecological quality status using periphytic ciliates in marine ecosystems

Abstract Our study focused on ciliates grazing potential against harmful algal blooms, because ciliates are considered as voracious feeders of toxic phytoplankton and major herbivores in marine food webs. Ciliates are major contributors to control the flux of harmful algal blooms by lessen the magnitude of their biomass from top to bottom by high consumption on these blooms. Keeping an eye on harmful algal blooms as common pollutant of marine ecosystem the community-based method was used to test the potential effects of two harmful algal species Alexandrium tamarense and Gymnodinum catenatum on the community patterns of the ciliates. For this purpose, the 14-day (mature) samples of ciliate communities were collected using glass slides as an artificial substratum at a depth of 1 m in coastal waters of the Yellow Sea, northern China. A series of algal cell concentrations of both species was prepared as 100 (control), following 102, 103, 104 and 105 cell ml−1, respectively. The study results indicated that both algal species showed strong effects on the community patterns of the ciliates at high concentration. Species abundance, relative species number and taxonomic distinctness indices of ciliate communities generally increased by increasing the concentration whereas, sharply decreased at the concentration level of (105 cells ml−1) for both algal species. Canonical analysis of principal coordinates demonstrated the variations in community structures of the ciliates driven by the concentrations of both algal species. Ellipse test showed an increased pattern in species departure from an expected breadth of species contour with increasing the algal cell concentrations. Based on our findings, it is suggested that extended studies on community-based bioassay is a valuable tool to strengthen the information about the effects of microalgae on the ciliate community structures.

Supplementation with Chlorella vulgaris, Chlorella protothecoides, and Schizochytrium sp. increases propionate-producing bacteria in in vitro human gut fermentation.

Gut microbiota are major contributors to host metabolism and are considered as potential targets of novel therapeutics. Microalgae have a strong potential for use as prebiotics because they are a rich source of proteins, fatty acids, fiber, and minerals for nutritional supplementation in humans. Nevertheless, there has been insufficient research into the effect of microalgae on gut microbiota. To investigate the effects of three edible microalgae (Chlorella vulgaris, Chlorella protothecoides, and Schizochytrium sp.) on gut microbiota, simulated digestion and colonic fermentation were examined. Following in vitro digestion, the microalgae displayed different levels of bioaccessibility and the nutrient analysis revealed that unabsorbed nutrients during the digestion process could be used for colonic fermentation. Following colonic fermentation, the control, inulin, and microalgae groups displayed different metabolite tendencies when investigated with nuclear magnetic resonance (NMR) spectroscopic analysis. In particular, microalgae supplementation increased the proportion of propionate in the colonic culture (control: 19.14%, Inulin: 18.38%, C. vulgaris: 25.80%, C. protothecoides: 25.46%, and Schizochytrium sp.: 25.56%). Microbial profiling analysis using 16S rRNA gene sequencing also disclosed that the relative abundance of Bacteroides (control: 1.91%, inulin: 2.61%, C. vulgaris: 14.77%, C. protothecoides: 11.17%, and Schizochytrium sp.: 5.51%) and Dialister (control: 0.08%, inulin: 2.06%, C. vulgaris: 6.79%, C. protothecoides: 4.45%, and Schizochytrium sp.: 4.48%), involved in propionate metabolism increased more than in the inulin group. Our findings suggest the potential use of microalgae as a functional food to increase propionate generation because propionate has been reported to be effective in weight loss and the inhibition of pathogen infection. © 2020 Society of Chemical Industry.