Sustainable alternatives to fish meal are increasingly required to minimize the environmental impact of aquaculture feeds. This study focuses on incorporation of microalgae Spirulina platensis and Chlorella vulgaris in rainbow trout’s (Oncorhynchus mykiss) feed replacing 25 and 50

BACKGROUND:Chlorella vulgaris is rich in protein, beneficial fatty acids and antioxidants, making it a promising natural feed additive. OBJECTIVES:This study evaluates the effects of dietary supplementation with the microalgae C. vulgaris on the productivity and egg quality of laying hens. METHODS:In a randomized design, 84 Lohmann Brown hens (47 weeks old) were divided into four groups: a control and three groups receiving 0.1%, 0.3%, or 0.5% C. vulgaris biomass in their feed over 8 weeks. Egg production, laying intensity, egg weight and composition were monitored. RESULTS:The 0.5% supplementation significantly increased egg production and laying intensity, without affecting egg weight. Eggs from microalgae-supplemented hens showed largely stable protein, fat and energy content, while dose-dependent trends were observed for cholesterol (increasing up to 275 mg/100 g in the highest dose) and the omega-6/omega-3 ratio (rising from 7.75:1 in CON to 16:1 in CV5). CONCLUSIONS:These results indicate that C. vulgaris supplementation can improve egg yield and potentially enhance nutritional value, though care is needed regarding lipid profile changes. The study supports the use of microalgae as a sustainable feed additive in poultry diets, promoting productivity and contributing to environmentally friendly egg production.

The dairy industry generates large volumes of whey, a nutrient rich by-product that is a threat to the environment because of a high lactose concentration. In this research, a potential of four microalgae strains – Tetradesmus obliquus MSCL 1710, Graesiella emersonii MSCL 1711, Chlorella vulgaris CCAP 211/111 and Scenedesmus quadricauda CCAP 276/16 was investigated to evaluate their growth under heterotrophic and mixotrophic conditions of lactose and its monosaccharides. This work specifically compares sweet whey (SW) and acid whey (AW) as a promising substrates for microalgal growth and lipid synthesis. Peculiar focus was given to local isolates—G. emersonii MSCL 1711 and T. obliquus MSCL 1710 cultivated in sweet (SW) and acidic whey (AW) at different concentrations and temperatures (15 °C and 25 °C). Mixotrophic cultivation in SW enhanced biomass productivity, with G. emersonii MSCL 1711 achieving 0.30 g/L/d and T. obliquus MSCL 1710 0.29 g/L/d at 25 °C. The highest lipid accumulation was observed in SW for G. emersonii MSCL 1711 at 15 °C, representing a 158.31

This study aimed to detect an impact of water–ethanol extracts of different microalgae species—Spirulina platensis, Dunaliella salina and Chlorella vulgaris—on the accumulation of bioactive compounds in tomatoes. A treatment with the corresponding ethanol solution and pure drinking water was used as a control. Tomato cultivar ‘Belle’ F1 (Enza Zaden) was grown in a polycarbonate greenhouse, in 25 L pots filled with a peat substrate (pH KCl 5.5). The plants were sprayed weekly from germination until the start of harvesting, in total nine times. Fruits were analysed at the stage of full ripeness. Bioactive compounds’ contents such as vitamin C, titratable acidity, pH value, β-carotene, lycopene, anthocyanin, total phenols as well as total soluble solids and dry matter were analysed, and the connection between fruit mass and the taste index was determined. The influence of the tested extracts on the bioactive compounds and quality parameters of tomatoes was different, but no significant differences for most of the analysed active compounds were found, with the exception of total phenols (from 137.59 ± 1.34 to 166.93 ± 2.01 mg 100 g−1) and total soluble solids (from 3.93 ± 0.12 to 4.4 ± 0.18 °Brix). In the next research, a more detailed study about the influence of the ethanol concentration on changes in biologically active compounds should be provided.

During this research microalgal strains of Graesiella emersonii KM01 and Tetradesmus obliquus OM02 were isolated from various freshwater bodies, also microalgal cultures Chlorella vulgaris CCAP 211/111, Scenedesmus quadricauda CCAP 276/16, Chromochloris zofingiensis CCAP 211/14 were from Culture Collection of Algae and Protozoa (CCAP, United Kingdom) and Galdieria sulphuraria UTEX 2919 from Culture Collection of Algae of the University of Texas at Austin (UTEX, USA). It has been shown that to increase microalgae biomass yield, it is possible to cultivate microalgae mixotrophically in whey medium. By comparing growth performance of microalgal cultures in lactose containing media and whey, a promising approach for achieving high biomass yield, thus also for decreasing environmental impact of improper whey disposal, was demonstrated for T. obliquus OM02. Growth of both G. emersonii KM01 and C. zofiengiensis CCAP 211/14 on lactose containing media and whey was found to be relatively low, not exceeding biomass productivity of isolate T. obliquus OM02. Cultivation of T. obliquus OM02 in whey demonstrated that it is possible to achieve the highest biomass in 50 % diluted whey, which resulted in 2.83 ± 0.11 g/L and is the highest yield between microalgal isolates in this research. Results confirm that mixotrophic cultivation of certain lactose assimilating microalgal isolates in whey compared to photoautotrophic cultivation enables to obtain a comparable biomass yield, which can be attributed to whey medium composition.

Industrial production of bacterial cellulose (BC) remains challenging due to significant production costs, including the choice of appropriate growth media. This research focuses on optimization of cheese whey (CW) based media for enhanced production of BC. Two modifications were made for CW medium for BC production with Komagataeibacter rhaeticus MSCL 1463. BC production in a medium of enzymatically hydrolyzed CW (final concentration of monosaccharides: glucose 0.13 g L−1, galactose 1.24 g L−1) was significantly enhanced, achieving a yield of 4.95 ± 0.25 g L−1, which markedly surpasses the yields obtained with the standard Hestrin‐Schramm (HS) medium containing 20 g L−1 glucose and acid‐hydrolyzed CW (final concentration of monosaccharides: glucose 1.15 g L−1, galactose 2.01 g L−1), which yielded 3.29 ± 0.12 g L−1 and 1.01 ± 0.14 g L−1, respectively. We explored the synergistic effects of combining CW with various agricultural by‐products (corn steep liquor (CSL), apple juice, and sugar beet molasses). Notably, the supplementation with 15% corn steep liquor significantly enhanced BC productivity, achieving 6.97 ± 0.17 g L−1. A comprehensive analysis of the BC's physical and mechanical properties indicated significant alterations in fiber diameter (62–167 nm), crystallinity index (71.1–85.9%), and specific strength (35–82 MPa × cm3 g−1), as well as changes in the density (1.1–1.4 g cm−3). Hydrolyzed CW medium supplemented by CSL could be used for effective production of BC.

The experiments were done at two farms in Latvia. Primocane raspberries were weekly sprayed with solutions of ethanol extractions of microalgae species of Spirulina sp., Dunaliella sp. and Chlorella sp. in different concentrations from stages of shoot growth to fruit ripening. During the season, dynamics of the shoot growth, beginning of flowering and fruit ripening were recorded. After the treatments, productive length of the shoots, number of flower trusses and leaves per shoot, number of productive shoots per plot, chlorophyll index, average fruit weight and sugar content in the fruits were measured. Certain positive effects of the treatments with one or another algae extraction were observed, increasing plant height and the proportion of the productive part of the shoot, number of leaves and flower trusses per shoot and the chlorophyll index. Moreover, no negative effects of any tested treatments were observed. However, the positive effects differed in different farms and years. That can be explained by uneven growth of the plants in the farms, weed and disease spread, changing weather conditions. Therefore, we can conclude that since the results are strongly promising, further experiments in controlled environments using preparations of varied extraction types, microalgae species and different treatment protocols should be carried out.

The present study aimed to investigate the effect of solution of ethanol extractions of different microalgae species: Spirulina sp., Dunaliella sp. and Chlorella sp. on the accumulation of biologically active compounds in tomato fruits. Ethanol solution as well as treatment with drinking water were used as a control. Tomato cultivar ‘Belle’ F1 (Enza Zaden) was grown in 25 L pots, in peat substrate (pHKCl 5.5, producer Laflora LTd), polycarbonate greenhouse. Chemical composition – total carotenoids, lycopene and β-carotene content, total phenolics and anthocyanins, organic acids, vitamin C as well as dry matter, pH and soluble solids content – was determined in tomato fruits at the stage of full ripen. The influence of tested extracts on biologically active compounds on quality parameters of tomatoes was different, but no negative effect was observed. As only pH values as well as total phenol content and total soluble solids had statistically significant differences, results can be described with genetical stability of the cultivar.

Production costs of bacterial cellulose (BC) can be reduced using alternative fermentation media, e. g., various agricultural by-products including whey. This study focuses on whey as an alternative growth medium for BC production by Komagataeibacter rhaeticus MSCL 1463. It was shown that the highest BC production on whey was 1.95 ± 0.15 g/L, which is approximately 40–50% lower that BC production on standard HS media with glucose. It was also confirmed that K. rhaeticus MSCL 1463 can utilise both lactose and galactose as the sole C source in the modified HS medium. Different whey pre-treatment methods showed that the highest BC synthesis with K. rhaeticus MSCL 1463 was achieved in undiluted whey after standard pre-treatment procedure. Moreover, BC yield from substrate on whey was significantly higher (34.33 ± 1.21%) compared to the HS medium (16.56 ± 0.64%), which shows that whey can be used as a potential fermentation medium for BC production.

Currently dairy processing by-products, such as whey, still propose a significant threat to the environment if unproperly disposed. Microalgal bioconversion of such lactose containing substrates can be used for production of valuable microalgae-derived bio-products as well as for significant reduction of environmental risks. Moreover, it could significantly reduce microalgae biomass production costs, being a significant obstacle in commercialization of many microalgae species. This review summarizes current knowledge on the use of lactose containing substrates, e.g. whey, for the production of value-added products by microalgae, including information on producer cultures, fermentation methods and cultivation conditions, bioprocess productivity and ability of microalgal cultures to produce β-galactosidases. It can be stated, that despite several limitations lactose-containing substrates can be successfully used for both—the production of microalgal biomass and removal of high amounts of excess nutrients from the cultivation media. Moreover, co-cultivation of microalgae and other microorganisms can further increase the removal of nutrients and the production of biomass. Further investigations on lactose metabolism by microalgae, selection of suitable strains and optimisation of the cultivation process is required in order to enable large-scale microalgae production on these substrates.

Up to date research on microalgae as plant biostimulants remains fragmented and use of living microalgal cell suspensions is understudied. This research focuses on use of Scenedesmus quadricauda and Chlorella vulgaris living-cells suspensions as growth stimulants for garden cress (Lepidium sativum). Different concentrations of microalgal biomass suspensions were tested. It was found that plant treatment with S. quadricauda biomass 0.8 g/L (dry weight) suspension resulted in a significant improvement in L. sativum seeds germination and growth rate.

Use of alternative cultivation substrates, for instance dairy industry by-products, can significantly reduce the production costs of microalgal biomass. However, dairy by-products are found to be problematic co-substrate for many microalgae, due to inability to hydrolyse lactose. The focus of this study was to assess the ability of microalgal strains to produce biomass in media supplemented with lactose, glucose and galactose. Among them only microalgae Chromochloris zofingiensis was capable to assimilate effectively all three sugars.

Biomaterials and biopolymers, such as bacterial cellulose (BC), are becoming increasingly important as sustainable materials with a wide range of potential applications. However, BC industrial production is associated with several difficulties such as low BC production yields and high production costs; therefore, cheap alternative growth media, e.g. apple juice are being studied intensively. The aim of this study is to evaluate BC synthesis under static conditions on apple juice medium (AJM). The optimal concentration of apple juice in unsupplemented AJM for Novacetimonas hansenii MSCL 1646 was shown by its dilution 1:6 with water, which resulted in 0.89 ± 0.01 g/L of dry BC weight after 10 cultivation days. Low BC synthesis can be associated with insufficient N concentration in apple juice; therefore, different organic and inorganic N sources were evaluated in combination with AJM, and beef extract (5 g/L) was found to be the most suitable. Further, AJM optimisation experiment showed the optimal apple juice and beef extract concentrations as 1:2 and 15 g/L respectively, which resulted in 17.27 ± 0.07 g/L of dry BC weight, which is significantly higher than in standard Hestrin-Schramm (HS) medium (4.07 ± 0.02 g/L). Analysis of mechanical and physical properties showed that use of AJM results in changes in BC properties compared with the standard HS medium. Results of the study indicate that apple juice is an effective and cheap C source that in combination with appropriate N source leads to high BC synthesis and makes it suitable for industrial BC production. • Low quality apples can be used as raw material for BC production; • Beef extract improves BC synthesis in apple juice medium; • Use of apple juice and beef extract affect mechanical properties of BC.

Garden berries and grapes constitute an integral part of a healthy and functional diet. Reduction of post-harvest losses can maximize the shelf life of berry fruits, increasing their market value and promoting consumption. Among current storage techniques, the use of edible films is an emerging strategy for packaging and protecting the surface of small fruits. They provide the necessary barrier for berries against adverse external biotic or abiotic factors while supporting the necessary physiological processes such as moisture and gas exchange. Carbohydrate polymers are an important component of edible films. The desired mechanical strength as well as barrier properties are achieved by combining carbohydrate polymers with other bio-based compounds, such as lipids, proteins, and functional additives. Unlike plant polysaccharides, the studies and use of microbial extracellular polysaccharides (EPSs) remain scarce, especially for films and coatings of garden berries and grapes. This review summarizes the available data for currently used (xanthan, pullulan, gellan, dextran, bacterial cellulose) and prospective microbial EPSs (levan, curdlan, kefiran, bacterial alginate). Directions in future research to achieve more widespread, cost-effective, environmentally friendly production and applications of edible microbial EPS films are discussed.

Current research in industrial microbiology and biotechnology focuses on the production of biodegradable microbial polymers as an environmentally friendly alternative to the still dominant fossil hydrocarbon-based plastics. Bacterial cellulose (BC) is important among microbial polymers due to its valuable properties and broad applications in variety of fields from medical to industrial technologies. However, the increase in BC production and its wider deployment is still limited by high costs of traditionally used raw materials. It is therefore necessary to focus on less expensive inputs, such as agricultural and industrial by-products or waste including the more extended use of glycerol. It is the environmentally harmful by-product of biofuel production and reducing it will also reduce the risk of environmental pollution. The experimental data obtained so far confirm that glycerol can be used as the renewable carbon source to produce BC through more efficient and environmentally friendly bioprocesses. This review summarizes current knowledge on the use of glycerol for the production of commercially prospective BC, including information on producer cultures, fermentation modes and methods used, nutrient medium composition, cultivation conditions, and bioprocess productivity. Data on the use of some related sugar alcohols, such as mannitol, arabitol, xylitol, for the microbial synthesis of cellulose are also considered, as well as the main methods and applications of glycerol pre-treatment briefly described.

Structurally diverse biopolymers, including extracellular polysaccharides (EPS), synthesized by bacteria can possess physicochemical and functional properties that make them important products of microbial synthesis with a broad and versatile biotechnological potential. Leuconostoc spp. belongs to the group of lactic acid bacteria as one of the predominant members and are relevant not only in varied food fermentations, but also can be employed in the production of extracellular homopolysaccharides (HoPS) such as α-glucans (dextran, alternan) and β-fructans (levan,inulin) from the sucrose-containing substrates. EPS are synthesized by specific Leuconostoc spp. extracellular glycosyltransferases [dextran sucrase, alternansucrase (ASR)] and fructosyltransferases (levansucrase, inulosucrase) and enzymatic reactions can be performed in whole culture systems as well as using cell-free enzymes. Both α-glucans and β-fructans have a wide range of properties, mostly depending on their pattern of linkages, which, although differing in some respects, make suitable prerequisites for their versatile application in many fields, especially in the food industry and biomedicine. As a rule, these properties (polymer type, molecular mass, rheological parameters), as well as the overall EPS yield, are strain-specific for the selected producers and depend to a large extent on the nutritional and growth conditions used, which in many cases remain not sufficiently optimized for Leuconostoc spp. This review summarizes the current knowledge on the potential of Leuconostoc spp. to produce commercially relevant EPS, including information on their applications in various fields, producer strains, production methods and techniques used, selected conditions, the productivity of bioprocesses as well as the possible use of renewable resources for their development.

Bacterial cellulose (BC) is a biopolymer with a wide range of potential applications starting from the food industry and biomedicine to electronics and cosmetics. Despite that, BC industrial production to date still is associated with certain difficulties. One of them is the high cost of growth media, which can reach up to 30% of production costs. To decrease production costs, use of industrial and agricultural by-products, including whey, as alternative growth media has been reported. Whey, as the main high-volume by-product of dairy industry, which is known for its low valorisation opportunities and negative environmental impact, can nevertheless be considered as an alternative growth medium for BC production. To date, several studies aimed at evaluating BC production on whey and lactose substrates have been reported, but they are still insufficient. Reviews of them showed that, in general, BC production on untreated whey- and lactose-containing media was lower than that on the standard medium. However, some wild and recombinant strains have been reported to produce BC on whey as good as the standard medium. Enzymatic and acidic pre-treatment of whey significantly enhanced BC yield. Changes in the microstructure of BC obtained from whey were also recognised, which should be considered regarding the impact on physical properties of the desired BC product. This mini-review indicates that currently whey can be recognised as quite a problematic alternative growth substrate for industrial BC production; however, further extensive studies may improve the prospects in both the search for a cheap alternative growth substrate for industrial BC production and valorisation of whey. KEY POINTS: • Whey is a by-product in which valorisation is still challenging. • Whey can be used for bacterial cellulose (BC) production. • BC yield and properties vary upon cultivation conditions and producer strains.

Current research in industrial microbiology and biotechnology focuses on the production of biodegradable microbial polymers as an environmentally friendly alternative to still dominant fossil-based plastics. Microbial polymers have an extensive biotechnological potential and are already widely used in a variety of fields ranging from medicine to technology. However, their increase in production and wider use is hampered by the high cost of raw materials and therefore requires a focus on cheaper inputs, including dairy by-products and waste such as cheese whey (CW). This is an environmentally unfriendly by-product of milk processing and reducing it would also reduce the risk of environmental pollution. This review summarises current knowledge on the use of CW and derived products to obtain commercially important microbial polymers, including information about producer cultures, fermentation techniques and methods used, composition of culture medium, cultivation conditions and productivity of bioprocesses. The main methods and applications of cheese whey pre-treatment are also summarised.