Methodological test of efficiency of heterotrophic potential ; Teste metodológico da eficiência do potencial de heterotrofia - DOI:10.4025/actascibiolsci.v29i2.526

This study aimed at describing the kinetic aspects of glucose aerobic mineralization by different types of microorganisms selected by filtration membranes of different pore sizes: 0.22, 0.45, 2.2 and 7.4 μm, and also in glass wool. Water samples were collected from Óleo Lagoon (21º36´ S and 47º49´ W). About 30 mg of glucose was added into filtered water, and the samples were incubated in the dark at 21ºC under aerobic conditions. The dissolved oxygen consumption was determined periodically during 59 days (polarographic method; DOmeter YSI model 58). The data were fitted into a first-order kinetic model. The maximum values of consumed oxygen varied from 2.10 mg L-1 (pore size 0.22 μm treatment) to 32.83 mg L-1 (pore size 0.45 μm treatment). The glucose mineralization on the 0.22 μm treatment showed the lowest oxygen consumption coefficient kd = 0.03 day-1 and half time (t1/2) = 23 days) and the highest value was observed on the 0.45 μm treatment and 2.2 μm treatment (kd = 0.08 day-1 and t1/2 = 9 days). Oxygen consumption was higher in the sample filtered into 0.45 μm, suggesting that bacterivory occurred in treatments with glass wool, 2.2 and 7.4 μm. The filtration into 0.22 μm pore size membranes favored chemical oxidation. ; Este estudo teve por objetivo descrever os aspectos cinéticos da mineralização aeróbia da glicose pela ação de diferentes tipos de microrganismos selecionados por membranas de filtração com diferentes tamanhos de poros: 0,22, 0,45, 2,2 e 7,4 μm e em lã de vidro; para tanto, utilizaram-se amostras de água coletadas na lagoa do Óleo (21º36´ S e 47º49´ W). Aproximadamente 30 mg de glicose foram adicionadas à água filtrada e distribuídas em frascos escuros (1 L) que foram incubados no escuro a 21ºC sob condições aeróbias. As concentrações de oxigênio dissolvido das incubações foram determinadas periodicamente, durante 59 dias (método polarográfico; oxímetro YSI modelo 58). Os consumos acumulados de oxigênio foram ajustados a um modelo cinético de primeira ordem. Os valores máximos de oxigênio ...