Effects of Chitooligosaccharide Coating Combined with Selected Ionic Polymers on the Stimulation of Ornithogalum saundersiae Growth

Recently, agricultural and horticultural sectors have shown an increased interest in the use of biopolymers and their derivatives as growth biostimulators. So far, coating is a little known method of applying the biostimulators. Our three-year study investigated coating the bulbs of Ornithogalum saundersiae with chitooligosaccharide (COS), sodium alginate, carrageenan, gellan gum and xanthan gum. The coating method was based on the formation of polyelectrolyte complexes. The COS with 48,000 g mol−1 molecular weight was contained by means of controlled free-radical degradation. Biopolymer coatings stimulated plant growth and flowering, total chlorophyll content, total polyphenol content and the levels of nitrogen, phosphorus, potassium and boron. The plants grown from the bulbs coated with COS + gellan gum exhibited the most vigorous growth, were first to flower, showed the highest antioxidant activity (DPPH), and the greatest content of pigments, polyphenols, l-ascorbic acid, potassium, phosphorus, zinc and manganese. These results suggest COS formulated with gellan gum shows promise as a potential biostimulator of plant growth

Polyhydroxyalkanoates - promising biodegradable polymers

W pracy omówiono polihydroksyalkanolany, biopolimery o ogromnym potencjale. Scharakteryzowano ich właściwości i zastosowanie, zwracając uwagę na takie ich zalety jak biozgodność (brak toksyczności w stosunku do organizmu), podatność na biodegradację, czy właściwości termoplastyczne, zbliżone do tworzyw sztucznych. Niestety, pomimo wielu zalet, PHA nie są powszechnie wykorzystywane, głównie ze względu na wysoki koszt ich wytwarzania i oczyszczania. Dlatego w celu obniżenia kosztów podejmuje się działania w kierunku zastąpienia podczas hodowli drobnoustrojów źródła węgla tanimi materiałami odpadowymi. Kolejnym sposobem zmniejszenia kosztów produkcji PHA jest wykorzystanie modyfikowanych genetycznie mikroorganizmów. Alternatywą może być także poszukiwanie nowych metod wyodrębniania biopolimeru z komórek. Dobrym pomysłem może być także łączenie chemicznych i mechanicznych metod oczyszczania PHA. PHA bardzo często wykorzystywane są w medycynie, zastępując tworzywa sztuczne, gdzie istotne są właściwości materiałów oraz ich podatność na biodegradację. Niestety, ze względu na cenę, do wytwarzania polimerowych przedmiotów użytku codziennego, polimery syntetyczne wykorzystywane są częściej.This paper discusses properties of polyhydroxyalkanoates (PHA), biopolymers with a huge potential for practical applications. PHA have a number of advantages such as biocompatibility (no toxicity for organism), biodegradability and thermoplastic properties similar to those of synthetic plastics. Unfortunately, despite these advantages PHA are not widely used owing to the high costs of their preparation and purification. Therefore, in order to reduce these costs efforts are being undertaken to replace traditional carbon sources for cultivation of microorganisms by cheaper waste materials. Another way to reduce the cost of PHA production is the use of genetically modified microorganisms. An alternative approach may be also a search for new methods for extraction of these biopolymer from the cells including combination of chemical and mechanical methods of purification. PHA are very often used in medicine, because of their properties and biodegradability. In this area they substitute plastics. Unfortunately, costs of production from PHA polymeric objects for everyday use are still too high, so synthetic polymers remain predominantly in use

Exopolysaccharide Gellan Gum and Derived Oligo-Gellan Enhance Growth and Antimicrobial Activity in Eucomis Plants

One of the visible trends in the cultivation of plants, particularly of medicinal ones, is the increasing interest of researchers in polysaccharides and their derivatives that show biostimulatory properties and are also safe to use. In the current study, we evaluated the effects of gellan gum and its depolymerized form oligo-gellan, on growth and antimicrobial activity of two ornamental species Eucomis bicolor and Eucomis comosa used in natural medicine. The biopolymers were applied in the form of bulb coating prepared by using polyelectrolyte complexes. In both species investigated, gellan gum and oligo-gellan enhanced the fresh weight of leaves and bulbs, the performance of the photosynthetic apparatus, and the leaf content of basic macronutrients. In comparison with the control, the plants treated with oligo-gellan accumulated more biomass, were first to flower, and had the highest leaf content of potassium. The extracts from the bulbs treated with gellan gum and oligo-gellan showed higher effectiveness in reducing the count of Bacillus atrophaeus, Escherichia coli, and Staphylococcus aureus than those from the bulbs not treated with the polysaccharides. The research described here largely expands our current knowledge on the effects of gellan gum derivatives and has a huge practical potential in agriculture production

Oligo-Alginate with Low Molecular Mass Improves Growth and Physiological Activity of Eucomis autumnalis under Salinity Stress

Biopolymers have become increasingly popular as biostimulators of plant growth. One of them, oligo-alginate, is a molecule that regulates plant biological processes and may be used in horticultural practice as a plant growth regulator. Biostimulators are mainly used to improve plant tolerance to abiotic stresses, including salinity. The aim of the study was to assess the effects of salinity and oligo-alginate of various molecular masses on the growth and physiological activity of Eucomis autumnalis. The species is an ornamental and medicinal plant that has been used for a long time in the traditional medicine of South Africa. The bulbs of E. autumnalis were coated using depolymerized sodium alginate of molecular mass 32,000; 42,000, and 64,000 g mol−1. All of these oligo-alginates fractions stimulated plant growth, and the effect was the strongest for the fraction of 32,000 g mol−1. This fraction was then selected for the second stage of the study, when plants were exposed to salt stress evoked by the presence of 100 mM NaCl. We found that the oligo-alginate coating mitigated the negative effects of salinity. Plants treated with the oligomer and watered with NaCl showed smaller reduction in the weight of the above-ground parts and bulbs, pigment content and antioxidant activity as compared with those not treated with the oligo-alginate. The study demonstrated for the first time that low molecular mass oligo-alginate may be used as plant biostimulator that limits negative effects of salinity in E. autumnalis

ENCAPSULATION OF ROXITHROMYCIN INTO GELLAN GUM MATRICES AND THE IMPACT OF OTHER NATURAL POLYMERS ON DRUG RELEASE

The aim of the work was to investigate the properties of polysaccharide matrices loaded with roxithromycin (ROX), made on the basis of low-acyl gellan and its blends with sodium alginate, pectin, karaya gum, methycellulose and κ-carageenan. The obtained formulations were investigated as potential oral dosage forms with the ability to protect it from the acidic conditions of the stomach. Another desired feature of the obtained systems was the sustained release of the active ingredient allowing for potential shifting the therapeutic effect to the colon. The morphology of the matrices was evaluated with optical and scanning electron microscopy. Moreover, Raman spectroscopy and thermal analysis were performed for ROX, polymers, ROX/polymers physical mixtures and the matrices. Next, the swelling behavior was examined. The matrices were evaluated for ROX content and encapsulation efficiency. The last stage concerned the drug release studies. All matrices after production revealed more or less oval shape with visible deformation most probably occurring during drying. Raman analysis and DSC confirmed the crystalline form of ROX and showed no evidence of interactions between the drug and the excipients. It was shown that the matrices containing gellan combined with methylcellulose or κ-carageenan at pH=7.4 released ROX slower than the other matrices which might be promising in terms of colonic drug delivery. Moreover, the polymer matrices remained physically stable at acidic pH similar to the environment of the stomach. However, in these conditions drug degradation was observed which indicates the necessity to further modify the applied technology