Políssacarídeo Liase – PL 8: ferramenta na modificação de exopolissacarídeos de Rhizobium sp.
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Data
2018-08-02
Autores
Sousa, Bruna Fernanda Silva de
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Universidade Estadual Paulista (Unesp)
Resumo
A produção de biopolímeros modificados é uma alternativa que vem sendo desenvolvida há pouco tempo com o objetivo de superar uma ou mais limitações dos exopolissacarídeos (EPS) nativos, e assim, aumentar a utilidade destes polímeros nas aplicações industriais. A descoberta de enzimas que atuam em exopolissacarídeo rizobianos a partir do sequenciamento de genomas e metagenomas é uma atividade recente. Tais enzimas podem ser utilizadas na preparação de EPS modificado com novas propriedades físico-químicas que resultem em novas aplicações na indústria de biopolímeros. Este trabalho teve como objetivo obter uma enzima polissacarídeo liase (PL) da família 8 a partir de prospecção em bancos de sequências do LBMP (FCAV/UNESP), além avaliar, a produção de EPS pelas diferentes estirpes rizobianas, aplicação da enzima xantana liase comercial bem como seu efeito na modificação da estrutura desses EPS, em comparação com a goma xantana. Foi possível obter uma enzima PL recombinante, com domínios conservados compartilhados entre membros da família PL 8. As estirpes avaliadas produziram quantidades significativas de EPS, e a partir dos resultados das técnicas aplicadas neste estudo, pode-se notar que todos os polímeros são heteropolissacarídeos específicos de rizobios nativos, sendo compostos principalmente por galactose e glicose, enquanto a goma xantana comercial tem a manose como o principal monômero. Tanto os EPS de origem rizobiana como a goma xantana tiveram suas estruturas modificadas pela ação da enzima xantana liase e remoção de grupos funcionais, quando avaliados através de técnicas espectroscópicas FTIR e RMN. Além do aumento resistência a elevadas temperaturas dos EPS modificados LMG 8819, H152 e SEMIA 4077 não alterados pelo tratamento. O conhecimento da composição dos EPS modificados agora facilitará futuras investigações relacionando a estrutura e a dinâmica do polissacarídeo frente às propriedades reológicas.
The production of modified biopolymers is an alternative that has recently been developed with the objective of overcoming one or more limitations of native exopolysaccharides (EPS), and thus, to increase the usefulness of these polymers in industrial applications. The discovery of enzymes that act on exopolysaccharide rhizobians from the sequencing of genomes and metagenomics is a recent activity. Such enzymes we used in the preparation of modified EPS with novel physicochemical properties that result in new applications in the biopolymer industry. The objective of this study was to obtain a polysaccharide lyase (PL) enzyme from family 8 from LBMP (FCAV / UNESP) sequencing banks, in addition to evaluating EPS production by the different rhizobia strains, commercial xanthan lyase enzyme as well as its effect on modifying the structure of these EPS compared to xanthan gum. It was possible to obtain a recombinant PL enzyme, with conserved domains shared between PL 8 family members. The evaluated strains produced significant amounts of EPS, and from the results of the techniques applied in this study, it we noticed that all the polymers are specific heteropolysaccharides of native rhizobia, being composed mainly by galactose and glucose, whereas the commercial xanthan gum has the mannose as the main monomer. Both rhizobial EPS and xanthan gum had their structures modified by the action of the xanthan lyase enzyme on glycosidic β bonds (1→4) and functional groups were removed when evaluated by FTIR and RMN spectroscopic techniques. In addition to the increased resistance to high temperatures of modified EPS (LMG 8819, H152) and SEMIA 4077 unaltered by the treatment. The knowledge of the composition of the modified EPS will now facilitate future investigations relating the structure and dynamics of the polysaccharide against rheological properties.
The production of modified biopolymers is an alternative that has recently been developed with the objective of overcoming one or more limitations of native exopolysaccharides (EPS), and thus, to increase the usefulness of these polymers in industrial applications. The discovery of enzymes that act on exopolysaccharide rhizobians from the sequencing of genomes and metagenomics is a recent activity. Such enzymes we used in the preparation of modified EPS with novel physicochemical properties that result in new applications in the biopolymer industry. The objective of this study was to obtain a polysaccharide lyase (PL) enzyme from family 8 from LBMP (FCAV / UNESP) sequencing banks, in addition to evaluating EPS production by the different rhizobia strains, commercial xanthan lyase enzyme as well as its effect on modifying the structure of these EPS compared to xanthan gum. It was possible to obtain a recombinant PL enzyme, with conserved domains shared between PL 8 family members. The evaluated strains produced significant amounts of EPS, and from the results of the techniques applied in this study, it we noticed that all the polymers are specific heteropolysaccharides of native rhizobia, being composed mainly by galactose and glucose, whereas the commercial xanthan gum has the mannose as the main monomer. Both rhizobial EPS and xanthan gum had their structures modified by the action of the xanthan lyase enzyme on glycosidic β bonds (1→4) and functional groups were removed when evaluated by FTIR and RMN spectroscopic techniques. In addition to the increased resistance to high temperatures of modified EPS (LMG 8819, H152) and SEMIA 4077 unaltered by the treatment. The knowledge of the composition of the modified EPS will now facilitate future investigations relating the structure and dynamics of the polysaccharide against rheological properties.
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Palavras-chave
Prospecção, Enzima recombinante, Xantana liase, Estirpes rizobianas, Estruturas de EPS