Algae as an alternative source of protein in poultry diets for sustainable production and disease resistance: present status and future considerations

Integrating algae into poultry diets offers a promising avenue for enhancing nutrition, boosting sustainability efforts, and potentially stimulating disease resistance. This comprehensive review delves into the essence, diversity, chemical composition, and nutritional merits of algae, spotlighting their emergence as innovative nutrient sources and health supplements for poultry. The growing interest in algae within poultry nutrition stems from their diverse nutritional profile, boasting a rich array of proteins, lipids, amino acids, vitamins, minerals, and antioxidants, thus positioning them as valuable feed constituents. A key highlight of incorporating both macroalgae and microalgae lies in their elevated protein content, with microalgae varieties like Spirulina and Chlorella exhibiting protein levels of up to 50-70%, outperforming traditional sources like soybean meal. This premium protein source not only furnishes vital amino acids crucial for muscular development and overall health in poultry but also serves as an exceptional reservoir of omega-3 fatty acids, notably eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), presenting multiple health benefits for both poultry and consumers alike. Moreover, algae boast antioxidant properties attributed to bioactive compounds like phycocyanin and astaxanthin, mitigating oxidative stress and boosting the bird's immune response, thereby fostering robust health and disease resilience. Incorporating macroalgae and microalgae into poultry diets yields positive impacts on performance metrics. Research evidence underscores the enhancement of growth rates, feed conversion ratios, carcass quality, and meat attributes in broilers, while in layers, supplementation promotes increased egg production, superior egg quality, and increased concentrations of beneficial nutrients such as omega-3 fatty acids. Furthermore, algae hold promise for mitigating the environmental footprint of poultry production, though significant outcomes from trials remain sporadic, necessitating further research to elucidate optimal dosages and blends for different algae species in poultry diets. Standardizing the composition of algae utilized in research is imperative, paving the way for potential applications in poultry nutrition as growth stimulants and substitutes for antibiotics. Nonetheless, a deeper understanding of dosage, combination, and mechanism of action through rigorous scientific investigation is key to unlocking algae's full potential within poultry nutrition.

Identification of Metabolites with Antibacterial Activities by Analyzing the FTIR Spectra of Microalgae

Biologically active substances from microalgae can exhibit antioxidant, immunostimulating, antibacterial, antiviral, antitumor, antihypertensive, regenerative, and neuroprotective effects. Lipid complexes of microalgae Chlorella vulgaris and Arthrospira platensis exhibit antibacterial activity and inhibit the growth of the Gram-positive strain Bacillus subtilis; the maximum zone of inhibition is 0.7 ± 0.03 cm at all concentrations. The carbohydrate-containing complex of C. vulgaris exhibits antibacterial activity, inhibits the growth of the Gram-positive strain B. subtilis, Bacillus pumilus; the maximum zone of inhibition is 3.5 ± 0.17 cm at all concentrations considered. The carbohydrate complex of A. platensis has antimicrobial activity against the Gram-negative strain of Escherichia coli at all concentrations, and the zone of inhibition is 2.0–3.0 cm. The presence of mythelenic, carbonyl groups, ester bonds between fatty acids and glycerol in lipid molecules, the stretching vibration of the phosphate group PO₂, neutral lipids, glyco- and phospholipids, and unsaturated fatty acids, such as γ-linolenic, was revealed using FTIR spectra. Spectral peaks characteristic of saccharides were found, and there were cellulose and starch absorption bands, pyranose rings, and phenolic compounds. Both algae in this study had phenolic and alcohol components, which had high antibacterial activity. Microalgae can be used as biologically active food additives and/or as an alternative to antibiotic feed in animal husbandry due to their antibacterial properties.

Recent advances in biological properties of brown algae-derived compounds for nutraceutical applications

The increasing demand for nutraceuticals in the circular economy era has driven the research toward studying bioactive compounds from renewable underexploited resources. In this regard, the exploration of brown algae has shown significant growth and maintains a great promise for the future. One possible explanation could be that brown algae are rich sources of nutritional compounds (polyunsaturated fatty acids, fiber, proteins, minerals, and vitamins) and unique metabolic compounds (phlorotannins, fucoxanthin, fucoidan) with promising biological activities that make them good candidates for nutraceutical applications with increased value-added. In this review, a deep description of bioactive compounds from brown algae is presented. In addition, recent advances in biological activities ascribed to these compounds through in vitro and in vivo assays are pointed out. Delivery strategies to overcome some drawbacks related to the direct application of algae-derived compounds (low solubility, thermal instability, bioavailability, unpleasant organoleptic properties) are also reviewed. Finally, current commercial and legal statuses of ingredients from brown algae are presented, considering future therapeutical and market perspectives as nutraceuticals.

Algal Phlorotannins as Novel Antibacterial Agents with Reference to the Antioxidant Modulation: Current Advances and Future Directions

The increasing drug resistance of infectious microorganisms is considered a primary concern of global health care. The screening and identification of natural compounds with antibacterial properties have gained immense popularity in recent times. It has previously been shown that several bioactive compounds derived from marine algae exhibit antibacterial activity. Similarly, polyphenolic compounds are generally known to possess promising antibacterial capacity, among other capacities. Phlorotannins (PTs), an important group of algae-derived polyphenolic compounds, have been considered potent antibacterial agents both as single drug entities and in combination with commercially available antibacterial drugs. In this context, this article reviews the antibacterial properties of polyphenols in brown algae, with particular reference to PTs. Cell death through various molecular modes of action and the specific inhibition of biofilm formation by PTs were the key discussion of this review. The synergy between drugs was also discussed in light of the potential use of PTs as adjuvants in the pharmacological antibacterial treatment.

A Comprehensive Review on Ulvan Based Hydrogel and Its Biomedical Applications

Ulvan is a natural sulfated polysaccharide obtained from marine green algae composed of 3-sulfated rhamnoglucuronan as the main component. It has a unique chemical structure that rich of L-rhamnosa, D-glucuronic acid, and L-iduronic acid. Ulvan has a similar structure to glycosaminoglycans (GAGs) in mammals including chondroitin sulfate, dermatan sulfate, and heparan sulfate that has broad range applications for many years. Here, we provide an overview of ulvan based hydrogels for biomedical applications. Hydrogels are one of ulvan advances in polymer science for application in drug delivery, tissue engineering, and wound healing. This review presented an overview about functional information of ulvan based hydrogels and the promising potential in biomedicals collected from published papers in Scopus, PubMed, and Google Scholar. Other important aspects concerning properties, hydrogel-forming mechanisms, and ulvan based hydrogel developments were reported as well. As conclusion, ulvan showed interesting properties in forming hydrogels and promising advances in biomedical applications.

Edible Seaweeds and Spirulina Extracts for Food Application: In Vitro and In Situ Evaluation of Antimicrobial Activity towards Foodborne Pathogenic Bacteria

Research is more and more focused on studying and selecting food preservatives of natural origin. In this scenario, algae are an excellent source of bioactive compounds, among which are antimicrobials, whose presence is variable depending on the algal species and environmental conditions. The aim of the present study was to obtain, by a food grade approach, antimicrobial extracts from five species already approved as foods and to test their efficacy in vitro (agar well diffusion assay) and in situ (microbial challenge test) towards foodborne pathogenic bacteria. Moreover, the total phenolic compounds of the extracts were determined in order to evaluate possible correlations with the antimicrobial activity. Strains belonging to Salmonella spp., Listeria monocytogenes, Escherichia coli, Staphylococcus aureus, and Bacillus cereus were considered. Overall, the extracts showed a good antimicrobial activity in vitro towards all the tested microorganisms, especially L. monocytogenes (15 mm of inhibition diameter). The effect of inhibition was monitored during 24, 48 and 120 h showing a good persistence in time. Arthrospira platensis exerted the highest efficacy, further revealed towards L. monocytogenes on salmon tartare as bacteriostatic using 0.45% of the extract and bactericidal using 0.90%. The presence of phenolic compounds could be related to the antimicrobial activity but was not revealed as the main component of this activity. The extract with the highest phenolic content (18.79 ± 1.90 mg GAE/g) was obtained from Himanthalia elongata. The efficacy, confirmed also in a food matrix, might open perspectives for their application as food preservative.

A Review of the Varied Uses of Macroalgae as Dietary Supplements in Selected Poultry with Special Reference to Laying Hen and Broiler Chickens

Seaweeds comprise ca. 12,000 species. Global annual harvest is ca. 30.13 million metric tonnes, (valued ca. $11.7 billion USD in 2016) for various commercial applications. The growing scope of seaweed-based applications in food, agricultural fertilizers, animal feed additives, pharmaceuticals, cosmetics and personal care is expected to boost market demand. Agriculture and animal feed applications held the second largest seaweed market share in 2017, and the combined market is anticipated to reach much higher values by 2024 due to the impacts of current research and development targeting enhanced animal health and productivity. In general, seaweeds have been utilized in animal feed as a rich source of carbohydrates, protein, minerals, vitamins and dietary fibers with relatively well-balanced amino acid profiles and a unique blend of bioactive compounds. Worldwide, the animal nutrition market is largely driven by rising demand for poultry feeds, which represents ca. 47% of the total consumption for all animal nutrition. This review provides an overview of the utilization of specific seaweeds as sustainable feed sources for poultry production, including a detailed survey of seaweed-supplemented diets on growth, performance, gastrointestinal flora, disease, immunity and overall health of laying/broiler hens. Anti-microbial effects of seaweeds are also discussed.

Seaweeds as a Functional Ingredient for a Healthy Diet

Seaweeds have been used since ancient times as food, mainly by Asian countries, while in Western countries, their main application has been as gelling agents and colloids for the food, pharmaceuticals, and the cosmetic industry. Seaweeds are a good source of nutrients such as proteins, vitamins, minerals, and dietary fiber. Polyphenols, polysaccharides, and sterols, as well as other bioactive molecules, are mainly responsible for the healthy properties associated with seaweed. Antioxidant, anti-inflammatory, anti-cancer, and anti-diabetic properties are attributed to these compounds. If seaweeds are compared to terrestrial plants, they have a higher proportion of essential fatty acids as eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids. In addition, there are several secondary metabolites that are synthesized by algae such as terpenoids, oxylipins, phlorotannins, volatile hydrocarbons, and products of mixed biogenetic origin. Therefore, algae can be considered as a natural source of great interest, since they contain compounds with numerous biological activities and can be used as a functional ingredient in many technological applications to obtain functional foods.

Biological Activity of Hydrophilic Extract of Chlorella vulgaris Grown on Post-Fermentation Leachate from a Biogas Plant Supplied with Stillage and Maize Silage

Algae are employed commonly in cosmetics, food and pharmaceuticals, as well as in feed production and biorefinery processes. In this study, post-fermentation leachate from a biogas plant which exploits stillage and maize silage was utilized as a culture medium for Chlorella vulgaris. The content of polyphenols in hydrophilic extracts of the Chlorella vulgaris biomass was determined, and the extracts were evaluated for their antioxidant activity (DPPH assay), antibacterial activity (against Escherichia coli, Lactobacillusplantarum, Staphylococcus aureus, Staphylococcus epidermidis) and antifungal activity (against Aspergillus niger, Candida albicans, Saccharomyces cerevisiae). The use of the post-fermentation leachate was not found to affect the biological activity of the microalgae. The aqueous extract of Chlorella vulgaris biomass was also observed to exhibit activity against nematodes. The results of this study suggest that Chlorella vulgaris biomass cultured on post-fermentation leachate from a biogas plant can be successfully employed as a source of natural antioxidants, food supplements, feed, natural antibacterial and antifungal compounds, as well as in natural methods of plant protection.

Antibacterial and Antiviral Activities of Local Thai Green Macroalgae Crude Extracts in Pacific white Shrimp (Litopenaeus vannamei)

Macroalgae are potentially excellent sources of bioactive secondary metabolites useful for the development of new functional ingredients. This study was conducted to determine the antimicrobial efficacy of the hot water crude extracts (HWCEs) of three species of local Thai green macroalgae Ulva intestinalis (Ui), U. rigida (Ur), and Caulopa lentillifera (Cl) and a commercial ulvan from U. armoricana (Ua). Chemical analysis indicated that the HWCE of Ur showed the highest sulfate content (13.9% ± 0.4%), while that of Ua contained the highest uronic acid and carbohydrate contents (41.47% ± 4.98% and 64.03% ± 2.75%, respectively), which were higher than those of Ur (32.75% ± 1.53% and 51.02% ± 3.72%). Structural analysis of these extracts by Fourier-transform infrared (FTIR) spectroscopy revealed that these HWCEs are complex with a signal at 1250 cm-1 corresponding to S=O stretching vibrations, while the signals at 850 cm-1 were attributed to the C-O-S bending vibration of the sulfate ester in the axial position. These HWCEs showed the growth suppression against some pathogenic Vibrio spp. Interestingly, the HWCEs from Ui at concentrations of 5 and 10 mg/mL completely inhibited white spot syndrome virus (WSSV) in shrimp injected with HWCE-WSSV preincubated solutions. This inhibitory effect was further confirmed by the reduction in viral loads and histopathology of surviving and moribund shrimp.

Antimicrobial and Fermentation Potential of Himanthalia elongata in Food Applications

Himanthalia elongata is a brown oceanic seaweed rich in bioactive compounds. It could play an important role in food production because of its antimicrobial and antioxidant properties. Three strains belonging to the Lactobacillus casei group (Lactobacillus casei, Lactobacillus paracasei, and Lactobacillus rhamnosus) and a Bacillus subtilis strain were used for the solid-state fermentation of commercial seaweeds, and bacterial growth was monitored using the plate count method. High-pressure processing (HPP) was also employed (6000 bar, 5 min, 5 °C) before extraction. The antimicrobial activity of the extracts was tested in terms of the main food pathogenic bacteria (Salmonella spp., Listeria monocytogenes, Escherichia coli, Staphylococcus aureus, and Bacillus cereus), and the phenolic content was estimated using the Folin-Ciocalteau method. In addition, targeted UHPLC-MS² methods were used to unravel the profile of phlorotannins. H. elongata allowed the growth of the L. casei group strains and B. subtilis, showing the fermentability of this substrate. Significant antimicrobial activity toward L. monocytogenes was observed in the extracts obtained from unfermented samples, but neither fermentation nor HPP enhanced the natural antimicrobial activity of this seaweed species. The content in the phenolic compounds decreased because of the fermentation process, and the amount of phenolics in both the unfermented and fermented H. elongata extracts was very low. Despite phlorotannins being related to the natural antimicrobial activity of this brown seaweed, these results did not support this association. Even if fermentation and HPP were not proven to be effective tools for enhancing the useful compounds of H. elongata, the seaweed was shown to be a suitable substrate for L. casei group strains as well as for B. subtilis growth, and its extracts exhibited antimicrobial activity toward foodborne pathogens.

Potential Use of Seaweed Bioactive Compounds in Skincare-A Review

Modern lifestyles have developed new attention on appearance and personal care which attract a huge number of consumers towards cosmetic products. The demand for a skincare product with natural ingredients is rapidly increasing. Seaweeds are major resources for in-demand active compounds with a wide variety of applications. The use of seaweed-derived ingredients in cosmetic products has increased in recent years as many scientific studies have proved the potential skincare properties of seaweed bioactive compounds. This review emphasizes possible skincare properties of seaweed bioactive compounds. The review outlines the mechanism involved in skin problems including hyperpigmentation, premature skin aging, and acne in the first part while the second part focuses on the promising application of seaweeds in skin protection by highlighting the bioactive compound responsible for their bioactivity.

Antimicrobial and antiparasitic activities of three algae from the northwest coast of Algeria

The objective of this study was to investigate the biological activities of Algerian algae, Sargassum vulgare, Cladostephus hirsutus and Rissoella verruculosa. Antimicrobial activity of the crude extracts and their fractions was assessed using the disc diffusion assay, the minimum inhibitory concentration and the minimum bactericidal concentration. Antiparasitic activity was studied in vitro against the blood stream forms of Trypanosoma brucei brucei and the intraerythrocytic stages of Plasmodium falciparum. Ethyl acetate (EA) fractions of the three tested algae showed more potent antimicrobial activity against S. aureus (7-14.5 mm) and B. cereus (7-10.75 mm), MIC values ranged from 0.9375 to 7.5 mg mL-1 and MBC values > 15 mg mL-1. Concerning the antiparasitic activity, EA factions of S. vulgare (IC50 = 9.3 μg mL-1) and R. verruculosa (IC50 = 11.0 μg mL-1) were found to be more effective against T. brucei brucei, whereas the three EA fractions were little active against P. falciparum.

Phytochemical study of the headspace volatile organic compounds of fresh algae and seagrass from the Adriatic Sea (single point collection)

Performed phytochemical study contributes to the knowledge of volatile organic compounds (VOCs) of Halopteris filicina (Grateloup) Kützing, Dictyota dichotoma (Hudson) J. V. Lamouroux, Posidonia oceanica (L.) Delile and Flabellia petiolata (Turra) Nizamuddin from the Adriatic Sea (single point collection). VOCs were investigated by headspace solid-phase microextraction (HS-SPME) and analysed by gas chromatography and mass spectrometry (GC-MS/FID). H. filicina headspace contained dimethyl sulfide (DMS; 12.8%), C8-compounds (e.g. fucoserratene (I; 9.5%)), benzaldehyde (II; 8.7%), alkane C17, dictyopterene D and C (III, IV), tribromomethane (V), 1-iodopentane, others. F. petiolata headspace was characterized by DMS (22.2%), 6-methylhept-5-en-2-one (9.5%), C17 (9.1%), II (6.5%), compounds I-V. DMS (59.3%), C15 (14.5%), C17 (7.2%) and C19 (6.3%) dominated in P. oceanica headspace. Sesquiterpenes were found in D. dichotoma, predominantly germacrene D (28.3%) followed by other cadinenyl (abundant), muurolenyl and amorphenyl structures. Determined VOCs may be significant for chemosystematics and chemical communications in marine ecosystem.

Investigation of the antibiofilm capacity of peptide-modified stainless steel

Biofilm formation on surfaces is an important research topic in ship tribology and medical implants. In this study, dopamine and two types of synthetic peptides were designed and attached to 304 stainless steel surfaces, aiming to inhibit the formation of biofilms. A combinatory surface modification procedure was applied in which dopamine was used as a coupling agent, allowing a strong binding ability with the two peptides. X-ray photoelectron spectroscopy (XPS), elemental analysis, contact angle measurement and surface roughness test were used to evaluate the efficiency of the peptide modification. An antibiofilm assay against Staphylococcus aureus was conducted to validate the antibiofilm capacity of the peptide-modified stainless steel samples. XPS analysis confirmed that the optimal dopamine concentration was 40 µg ml^-1 in the coupling reaction. Element analysis showed that dopamine and the peptides had bound to the steel surfaces. The robustness assay of the modified surface demonstrated that most peptide molecules had bound on the surface of the stainless steel firmly. The contact angle of the modified surfaces was significantly changed. Modified steel samples exhibited improved antibiofilm properties in comparison to untreated and dopamine-only counterpart, with the peptide 1 modification displaying the best antibiofilm effect. The modified surfaces showed antibacterial capacity. The antibiofilm capacity of the modified surfaces was also surface topography sensitive. The steel sample surfaces polished with 600# sandpaper exhibited stronger antibiofilm capacity than those polished with other types of sandpapers after peptide modification. These findings present valuable information for future antifouling material research.

Seaweed Bioactive Compounds against Pathogens and Microalgae: Potential Uses on Pharmacology and Harmful Algae Bloom Control

Cyanobacteria are found globally due to their adaptation to various environments. The occurrence of cyanobacterial blooms is not a new phenomenon. The bloom-forming and toxin-producing species have been a persistent nuisance all over the world over the last decades. Evidence suggests that this trend might be attributed to a complex interplay of direct and indirect anthropogenic influences. To control cyanobacterial blooms, various strategies, including physical, chemical, and biological methods have been proposed. Nevertheless, the use of those strategies is usually not effective. The isolation of natural compounds from many aquatic and terrestrial plants and seaweeds has become an alternative approach for controlling harmful algae in aquatic systems. Seaweeds have received attention from scientists because of their bioactive compounds with antibacterial, antifungal, anti-microalgae, and antioxidant properties. The undesirable effects of cyanobacteria proliferations and potential control methods are here reviewed, focusing on the use of potent bioactive compounds, isolated from seaweeds, against microalgae and cyanobacteria growth.

Plant Growth Biostimulants Based on Different Methods of Seaweed Extraction with Water

We explored two methods for obtaining aqueous extracts: boiling and soaking of Baltic seaweeds (EB and ES, resp.). Algal extracts were characterized in terms of polyphenols, micro- and macroelements, lipids content, and antibacterial properties. The utilitarian properties were examined in the germination tests on Lepidium sativum for three extract dilutions (0.5, 2.5, and 10%). It was found that the extracts were similar in micro- and macroelement concentrations. Water was proved to be a good solvent to extract phenolic compounds. The algal extract produced by soaking biomass did not show inhibitory effect on Escherichia coli and Staphylococcus aureus. Only the boiled extract had an inhibitory activity against E. coli. Germination tests revealed a positive influence of the bioproducts on the cultivated plants. In the group treated with 10% EB, plants were 13% longer than in the control group; the content of elements B, Mo, Zn, and Na in the group treated with 10% ES was higher by 76%, 48%, 31%, and 59% than in the control group, respectively; the content of chlorophyll was 2.5 times higher in 0.5% ES than in the control group. Extracts showed the slight impact on the morphology of plants.

Chemical composition of red, brown and green macroalgae from Buarcos bay in Central West Coast of Portugal

Six representative edible seaweeds from the Central West Portuguese Coast, including the less studied Osmundea pinnatifida, were harvested from Buarcos bay, Portugal and their chemical characterization determined. Protein content, total sugar and fat contents ranged between 14.4% and 23.8%, 32.4% and 49.3% and 0.6-3.6%. Highest total phenolic content was observed in Codium tomentosum followed by Sargassum muticum and O. pinnatifida. Fatty acid (FA) composition covered the branched chain C13ai to C22:5 n3 with variable content in n6 and n3 FA; low n6:n3 ratios were observed in O. pinnatifida, Grateloupia turuturu and C. tomentosum. Some seaweed species may be seen as good sources of Ca, K, Mg and Fe, corroborating their good nutritional value. According to FTIR-ATR spectra, G. turuturu was associated with carrageenan seaweed producers whereas Gracilaria gracilis and O. pinnatifida were mostly agar producers. In the brown algae, S. muticum and Saccorhiza polyschides, alginates and fucoidans were the main polysaccharides found.

Seaweed extract by microwave assisted extraction as plant growth biostimulant

Microwave Assisted Extraction (MAE) was used to obtain aqueous extracts of Baltic seaweeds. Three different temperatures: 25, 40, 60°C were examined. Algal extracts were characterized in terms of polyphenols, micro- and macroelements, lipids content and antibacterial properties. This is the first study that examines the effect of algal extract obtained by MAE in plant cultivation. The utilitarian properties were checked in the germination tests on Lepidium sativum for three dilutions of extract (0.5, 2.5 and 10%). Results showed that the content of polyphenols in extracts decreased with temperature, whereas the content of micro- and macroalements increased with temperature. The aqueous extracts did not contain fatty acids and did not show inhibitory effect on Escherichia coli and Staphylococcus aureus. Germination tests showed that plants in the experimental groups with an optimal concentration of extract had a higher height, weight, chlorophyll and micro- and macroelement content than plants in the control group. The algal extracts did not significantly influence the morphology of plants as shown in SEM pictures. Results show that algal extracts obtained by MAE have the highest potential applied in agriculture as biostimulants.