This review presents a comprehensive and systematic study of the field of plant biostimulants and considers the fundamental and innovative principles underlying this technology. The elucidation of the biological basis of biostimulant function is a prerequisite for the development of science-based biostimulant industry and sound regulations governing these compounds. The task of defining the biological basis of biostimulants as a class of compounds, however, is made more complex by the diverse sources of biostimulants present in the market, which include bacteria, fungi, seaweeds, higher plants, animals and humate-containing raw materials, and the wide diversity of industrial processes utilized in their preparation. To distinguish biostimulants from the existing legislative product categories we propose the following definition of a biostimulant as ‘a formulated product of biological origin that improves plant productivity as a consequence of the novel or emergent properties of the complex of constituents, and not as a sole consequence of the presence of known essential plant nutrients, plant growth regulators, or plant protective compounds’. The definition provided here is important as it emphasizes the principle that biological function can be positively modulated through application of molecules, or mixtures of molecules, for which an explicit mode of action has not been defined. Given the difficulty in determining a ‘mode of action’ for a biostimulant, and recognizing the need for the market in biostimulants to attain legitimacy, we suggest that the focus of biostimulant research and validation should be upon proof of efficacy and safety and the determination of a broad mechanism of action, without a requirement for the determination of a specific mode of action. While there is a clear commercial imperative to rationalize biostimulants as a discrete class of products, there is also a compelling biological case for the science-based development of, and experimentation with biostimulants in the expectation that this may lead to the identification of novel biological molecules and phenomenon, pathways and processes, that would not have been discovered if the category of biostimulants did not exist, or was not considered legitimate.

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Biostimulants in Plant Science: A Global Perspective.

Prebiotics as functional foods: A review

Dietary fibres in pulse seeds and fractions: Characterization, functional attributes, and applications

The term "functional foods" comprises some bacterial strains and products of plant and animal origin containing physiologically active compounds beneficial for human health and reducing the risk of chronic diseases. Among the best known functional compounds probiotics, prebiotics and natural antioxidants should be given as examples. These substances can be obtained by biotechnological methods and by extraction from plant or animal tissues.

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Probiotics, prebiotics and antioxidants as functional foods.

High moisture extrusion cooking of pea protein isolates: Raw material characteristics, extruder responses, and texture properties

A simple method for the isolation and purification of alpha-galactosides, raffinose family oligosaccharides (RFOs), from legumes has been developed. The method includes (i) imbibition of seeds, (ii) extraction with 50% ethanol, (iii) precipitation of RFOs, (iv) purification of RFOs on diatomaceous earth and charcoal, and (v) cation-exchange chromatography. The described method allows one to obtain high purity RFO preparations (90% for lentil and 80% for pea seeds, determined by HPLC-RI analysis) in the form of white, fine powder. Yields of alpha-galactosides isolated from 100 g of seeds of lentil and pea were 5.6 and 4.3 g, respectively.

Simple Method of Isolation and Purification of α-Galactosides from Legumes

Effect of germination on the protein fraction composition of different lupin seeds

Synbiotics are synergistic combinations of prebiotics and probiotics. In chickens, synbiotics can be delivered in ovo to expedite colonization of the gut by beneficial bacteria. We therefore aimed to design synbiotics in vitro and validate them in broiler chickens upon in ovo delivery. The probiotic components of the synbiotics were Lactobacillus salivarius and Lactobacillus plantarum. Their growth was assessed in MRS medium supplemented with different prebiotics. Based on in vitro results (hatchability and growth curve), two synbiotics were designed: S1 –Lactobacillus salivarius with galactooligosaccarides (GOS) and S2 –Lactobacillus plantarum with raffinose family oligosaccharides (RFO). These synbiotics were delivered to Cobb broiler chicken embryos on day 12 of incubation at optimized doses (105 cfu egg-1 of probiotic, 2 mg egg-1 of prebiotic). Post hatching, 2,400 roosters were reared (600 individuals group-1 divided into eight replicate pens). Microbial communities were analyzed in ileal and cecal digesta on day 21 using FISH. Gene expression analysis (IL1β, IL4, IL6, IL8, IL12, IL18, IFNβ, and IFNγ) was performed on days 7, 14, 21, and 42 for the spleen and cecal tonsils with RT-qPCR. Body weight and feed intake of the roosters did not differ by the treatments. Microbial populations of Lactobacillus spp. and Enterococcus spp. in the ileum were higher in S1 and S2 than in the control. In the cecum, the control had the highest bacterial counts. S1 caused significant up-regulation of IL6, IL18, IL1β, IFNγ, and IFNβ in the spleen on day 21 and IL1β on day 7 (P < 0.05). In cecal tonsils, S1 caused significant down-regulation of IL12, IL8, and IL1β on day 42 and IFNβ on day 14 (P < 0.05). S2 did not elicit such patterns in any tissues investigated. Thus, we demonstrate that divergent effects of synbiotics in broiler chickens were reflected in in vitro tests.

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Synbiotics for Broiler Chickens—In Vitro Design and Evaluation of the Influence on Host and Selected Microbiota Populations following In Ovo Delivery

Two trials were conducted. The aim of the first trial, performed under field conditions, was the comparison of the rearing performance between the chickens injected in ovo with 1.9 mg of raffinose family oligosaccharides (RFOs) (experimental group E), and chickens administered with the antibiotics (control group C). Environmental and feed conditions were similar for both groups. The mortality, feed intake, and slaughter body weight were recorded from farm documentation. Feed conversion ratio (FCR) and European production efficiency factor (EPEF) were calculated. The aim of the second trial, performed under laboratory condition, was to determine the prebiotic effect of different doses of RFOs (0.5%, 1.0%, 3.0%, or 5.0%) on the growth of Bifidobacterium bifidum and Lactobacillus acidophilus in vitro. Prebiotic effect of RFOs administered with a single in ovo injection had a similar effect on broiler performance (survivability, growing period, and EPEF), to antibiotics given as growth promoters. Body weight and FCR was significantly higher in the group E in comparison to the group C. The prebiotic in vitro effect of RFOs was evident. The obtained data suggest that at least in the case of Bifidobacterium bifidum, RFOs could show the dose-dependent effects on the bacteria number. This work opens the opportunity of using, in technical scale, in ovo technology to deliver other bioactives to stimulate the prebiotic effect.

Field and in vitro study on prebiotic effect of raffinose family oligosaccharides in chickens

Biological activity tests were performed on alpha-galactoside preparations obtained from Lupinus angustifolius L. cv. Mirela (alkaloid-rich) and Pisum sativum L. cv. Opal seeds. The studies included the following tests: acute toxicity, cytotoxic test, delayed type hypersensitivity (DTH), plaque-forming cell number (IgM-PFC), and influence on the growth of bifidobacteria and coliform presence in rat colon. Results of these studies showed that alpha-galactosides from lupin and pea seeds were essentially nontoxic. Their acute toxicity (LD(50)) in mice was >4000 mg kg(-1) of body weight. alpha-galactoside preparations were not cytotoxic for mouse thymocytes in vitro. The in vitro test shows that oligosaccharides from lupin and pea are utilized by selected beneficial colon bacterium strains. The in vivo experiment demonstrated that alpha-galactosides from legume significantly influenced the growth of bifidobacteria in rats colon. Simultaneously, the decrease of the coliform presence was observed. The chemical composition of the tested preparations had no significant effect on their biological activity.

Piotr Gulewicz

Papers

Simple Method of Isolation and Purification of α-Galactosides from Legumes

Effect of germination on the protein fraction composition of different lupin seeds

Synbiotics for Broiler Chickens—In Vitro Design and Evaluation of the Influence on Host and Selected Microbiota Populations following In Ovo Delivery

Field and in vitro study on prebiotic effect of raffinose family oligosaccharides in chickens

Biological activity of α-galactoside preparations from Lupinus angustifolius L. and Pisum sativum L. seeds