ABSTRACT
Eight Fusarium sp. namely, F. acutatum, F. globosum, F. graminearum, F. lactis, F. nivale, F. proliferatum, F.pseudoanthophilum and F. robustum were screened for the presence of lectins by hemagglutination activityusing human ABO, porcine, ovine, goat and rabbit erythrocytes. Mycelial extracts of all the fungal culturesexcept F. graminearum displayed unique lectin activity with only rabbit erythrocytes. Enzymatic treatment ofrabbit erythrocytes with neuraminidase has significantly enhanced the titre of all the lectin-positive extractsof fungal cultures. In contrast, most of the lectins showed a decline in lectin activity with protease treatedrabbit erythrocytes. Saccharide specificity studies have shown that majority of the lectins are inhibitory towardsO-acetyl sialic acids. None of the lectins from Fusarium sp. were inhibited by dextran, meso-inositol, andN-acetyl-D-glucosamine. Most of the fungal cultures displayed highest hemagglutination activity during the10th day of growth in broth cultures. The unique saccharide specificity of Fusarium sp. lectins can be used forelucidating their clinical role in glycobiology research.
ABSTRACT
Optimization of critical medium components for exoinulinase production by Kluyveromyces marxianus YS-1 at shake-flask was investigated using response surface methodology (RSM) based on a central composite rotatable design (CCRD). A five-level with five factors CCRD was used to evaluate the influence of related factors including concentration of inulin, meat extract, calcium chloride, sodium dodecyl sulphate and medium pH. Optimum values obtained by RSM were 2 percent inulin, 2.17 percent meat extract, 0.65 mM calcium chloride, 0.10 mM sodium dodecyl sulphate and pH 5.5. Optimized medium projected a theoretical exoinulinase production of 63.61 IU/mL and biomass yield of 0.965 (OD600/10). Multiple correlation coefficient R was 0.9976 and 0.9605 for exoinulinase production and biomass yield, respectively, which being close to one, justified an excellent correlation between the predicted and experimental values. Maximum productivity of exoinulinase (64.05 IU/mL) obtained experimentally by RSM was more than double in comparison to earlier findings using classical one-variable-at-a-time technique.
Foi investigada a optimização de componentes criticos do meio de cultivo para a produção de exoinulinase por Kluyveromyces marxianus YS-1 em frascos agitados utilizando a metodologia de superficie de resposta (RSM), com base em um delineamento composto central rotativo. As variáveis independentes, com cinco niveis, foram as concentrações de inulina, de extrato de carne, de cloreto de cálcio e de dodecil sulfato de sódio, bem como o pH do meio de cultivo. Os valores ótimos, obtidos pela RSM, foram com 2 por cento de inulina, 2.17 por cento de extrato de carne, 0.65 mM de cloreto de cálcio, 0.10 mM de dodecil sulfato de sódio e pH 5.5. As estimativas de produção de exoinulinase e de rendimento em biomassa no meio otimizado foram de 63.61 UI/ml e de 9.65 (em termos de OD600/10), respectivamente. Os coeficientes de correlação múltipla R foram de 0.9976 e 0.9605 para produção de exoinulinase e biomassa, respectivamente, e, sendo próximos de um, indicam uma excelente correlação entre os valores estimados e experimentais. A máxima productividade de exoinulinase (64.05 UI/ml) obtida experimentalmente por RSM foi mais que o dobro em comparação com nossos resultados anteriores utilizando uma técnica de otimização clássica de uma variável por vez.