Activity of glycosidases from freshwater heterotrophic microorganisms on the degradation of extracellular polysaccharide produced by Anabaena spiroides (Cyanobacteria)

Abstract

The activity of specific glycosidases during the degradation of the extracellular polysaccharide (EPS) produced by Anabaena spiroides was determined using MUF-substrates (MUF-monosaccharides). Polysaccharide degradation was found to occur in a two-phase process. The first consisted of high enzymatic activity that consumed 41% of the EPS at a relatively high rate, while the second consumed the remaining polysaccharide (59%) at a slower rate. A transition phase from the higher to the slower degradation rates was marked by a replacement of bacterial populations from coccoid to bacillus cells. During the degradation process, the bacterial biomass increased with the decrease of EPS, as revealed by bacterial cell counts.

Dynamics of soluble extracellular polymeric ­substances and transparent exopolymer particle pools in coastal ecosystems

“…Mari & Burd (1998) used a model to predict TEP concentrations and demonstrated that bacterial degradation and grazing rate are essential to predict the real TEP concentrations in situ. It is well known that bacteria use a considerable fraction of phytoplankton production as a carbon source , Colombo et al 2004, Pacobahyba et al 2004). …”

Carboidratos dissolvidos do reservatório de Barra Bonita (Estado de São Paulo, Brasil) e sua relação com as algas fitoplanctônicas abundantes

“…A ramnose, a galactose e a glicose também foram os monossacarídeos mais abundantes registrados por Gouvêa et al (2005) em culturas de M. aeruginosa isoladas do reservatório de Barra Bonita, enquanto que Colombo et al (2004) registrou maior porcentagem de arabinose e glicose em amostras de A. spiroides, também isoladas deste reservatório. Outros estudos, como os de Gloaguen et al (1995) e Nicolaus et al (1999), também registraram elevadas concentrações destes açúcares em culturas de cianofíceas, como Anabaena sp., Anabaena tortulosa, Chroococcus minutus, Oscillatoria sp.…”

“…Como constituintes das substâncias húmicas e fúlvicas podem levar a um melhor entendimento dos mecanismos da gênese da matéria orgânica complexa e pela sua susceptibilidade de complexar-se com metais traços, podem controlar a disponibilidade destes no meio aquá-tico (Lombardi & Vieira 2000, Freire-Nordi et al 2005, Gouvêa et al 2005, Nogueira et al 2005. Desde que os polissacarídeos extracelulares podem ser usados como substrato por bactérias (Freire-Nordi & Vieira 1998, Colombo et al 2004, estes componentes podem realizar um importante papel na possível associação específica bactéria/alga (Grossart et al 2003). Também são os principais componentes do carbono orgânico liberado pelas algas e são extremamente variáveis na sua composição monossacarídica e estereo-química.…”

Rhamnose and hydrolysis of MUF-α-L- rhamnopyranoside coupled with producers of rhamnose-rich extracellular polysaccharides in a hypereutrophic reservoir

“…2). Rhamnose occurs at relatively high proportions in the EPS released by these 4 species (Colombo et al 2004, Giroldo et al 2005, Gouvêa et al 2005, Vieira et al 2008 (Table 3), which may explain this correlation. However, there was no statistically significant temporal correlation between the rhamnose concentration and total phytoplankton density, over the whole water column.…”

“…Their EPS, including released free colloids, capsules of A. spiroides and colonial matrices of M. aeruginosa, are important sources of rhamnose (Colombo et al 2004, Giroldo et al 2005, Gouvêa et al 2005, Vieira et al 2008). Released polysaccharides may induce an increase in the activity of glycosidases, α-L-rhamnosidase(s) among them, as already demonstrated for some species of phytoplankton (Chróst 1991, Vrba et al 1992.…”