Isolation, fractionation and some properties of polysaccharides produced in a bound form by Azospirillum brasilense and their possible involvement in Azospirillum-wheat root interactions

Abstract

It was shown that Azosp/r///um brasilense strains Sp7, Sp107, Sp245, and S17 when cultivated in a liquid synthetic malate medium to the end of the exponential phase of growth, produced at least two complex polysaccharide-containing components. The components were arbitrarily called lipopolysaccharide-protein complex and polysaccharide-lipid complex. These complexes were shown to interact with a wheat germ agglutinin. From polysaccharide-fipid complexes, acidic polysaccharides were isolated and their specific rotation, molecular masses, affinity for wheat germ agglutinin, and monosaccharide composition were determined. The polysaccharides of all strains contained rhanmose, galacturonic acid, and glucosamine, while the polysaccharides of strains Sp7 and $17 included additional fucose and mannose, respectively, and both had galactose. It is suggested that lipopolysaccharide-proteiu complexes, polysaccharide-lipid complexes, and polysaccharides may be involved in the process of interaction of azospirilla with wheat root surfaces. Key words: Azospirillum brasilense; Polysaccharide; Monosaccharide composition; Azosp/r///um-wheat root interaction * Corresponding author. germ agglutinin (WGA) existing on wheat roots [1] with the cell surface and polysacchadde (PS) components of Azospirillum have been considered in other studies [2-5]. Capsular polysaccharide (CPS) of A. brasilense Cd was presumed to include N-acetyl-D-glucosamine (GlcNAc) [3], a hapten specific to WGA. Later findings, however, cast some doubt on the presence of this monosaccharide in CPS [6]. No GlcNAc was found in the exopolysaccharide (EPS) of A. brasilense Sp7 or SSDI 0378-1097(94)00064-X

Peculiarities of the Structure of Azospirillum zeae and Azospirillum formosense Lipopolysaccharides

“…Условия культивирования микро-организмов и освобождения от капсулы пред-ставлены ранее [2]. ЛПС выделяли из сухих бактериальных клеток экстракцией горячим 45%-ным раствором фенола.…”

“…Содержание углеводов, 2-кето-3-дезокси-октоновой кислоты (КДО), фосфора, определяли колориметрическими методами, описанными в работе [2].…”

“…DOI: 10.18500/1816DOI: 10.18500/ -9775-2017 Азоспириллы являются ризосферными сво-бодноживущими диазобактериями (PGPR -plant growth-promoting rhizobacteria), вступающими в ассоциативный симбиоз с различными расте-ниями [1]. Липополисахариды, гликополимеры внешней мембраны клеточной стенки бактерий непосредственно вовлечены в образование рас-тительно-микробных ассоциаций [2]. На данный момент классифицировано 18 видов азоспи-рилл, среди них мало исследованы A. zeae и A. formosense как нет сведений и о структуре ЛПС этих бактерий, чему и посвящено настоя-щее исследование.…”

Extracellular polysaccharides and polysaccharide-containing biopolymers from Azospirillum species: properties and the possible role in interaction with plant roots

“…It was shown that in the PSLC from Sp 7 (S-form), the PS and the lipid moieties are held together by hydrophobic interactive forces [32]. In the other strains, the composition of the PSLCs may be similar or more complicated, involving both covalent bonds between the PS and the lipid moieties and hydrophobic interactions between the component parts of the complex [22,23].…”

“…The LPPCs and PSLCs from Sp 107 and Sp 246 were separated only after the blends of the complexes had been subjected to mild acid hydrolysis, and the chemically modi¢ed complexes to gel ¢ltra-tion. In this way, modi¢ed LPPCs and PSLCs from Sp 107 and Sp 246 were obtained [22,23].…”