AME 69:169-181 (2013)  -  DOI: https://doi.org/10.3354/ame01629

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

Armando Augusto Henriques Vieira*, Vanessa Colombo-Corbi, Inessa Lacativa Bagatini, Maria José Dellamano-Oliveira, Leticia Piton Tessarolli

Department of Botany, Federal University of São Carlos, Via Washington Luís km 235, PO Box 676, São Carlos 13565-905, São Paulo, Brazil

ABSTRACT: Water collected from several depths of the tropical hypereutrophic Barra Bonita Reservoir (Brazil) was analyzed monthly from August 2002 to January 2004. The concentration of rhamnose ranged from 0 to 3.8 µmol l-1, representing 28% of total dissolved neutral carbohydrates (TDnC) on average. Rhamnose concentration was linearly correlated with TDnC concentration and with the abundance of Microcystis aeruginosa, which releases a rhamnose-rich extracellular polysaccharide (EPS). This correlation was slightly stronger when the cell densities of Aulacoseira granulata, Cryptomonas tetrapyrenoidosa and Anabaena spiroides, also rhamnose-rich EPS producers, were included. The enzymatic activity on methylumbelliferyl (MUF)-α-L-rhamnopyranoside (EARh) ranged from 0 to 57.8 nmol MUF l-1 h-1. Glucose concentrations were found to vary from 0 to 4.15 µmol l-1 (27.5% of TDnC), and the enzymatic activity on MUF-β-D-glucopyranoside (EAGl) ranged from 7.4 to 116.9 nmol MUF l-1 h-1. Variation of EARh in time was directly correlated with the density of M. aeruginosa, and with rhamnose concentration in TDnC, while EAGl activity was correlated with density of M. aeruginosa only for variation with depth. Analysis of rhamnose, glucose, TDnC, EARh, EAGl, and bacterial density at each depth individually provided evidence that EPS released was employed as bacterial substrates, despite the permanent presence of TDnC from surface to bottom, owing to its constant production. These results also showed strong evidence that both enzymes were induced by EPS. Our results strongly suggest that the predominant phytoplankton species, known producers of rhamnose and glucose-rich EPS, α-L-rhamnosidase(s) activity and rhamnose concentration in the Barra Bonita Reservoir were coupled.


KEY WORDS: Rhamnose · MUF-α-L-rhamnopyranoside · α-L-rhamnosidase(s) · Microcystis aeruginosa · Extracellular polysaccharides


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Cite this article as: Vieira AAH, Colombo-Corbi V, Bagatini IL, Dellamano-Oliveira MJ, Tessarolli LP (2013) Rhamnose and hydrolysis of MUF-α-L- rhamnopyranoside coupled with producers of rhamnose-rich extracellular polysaccharides in a hypereutrophic reservoir. Aquat Microb Ecol 69:169-181. https://doi.org/10.3354/ame01629

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