STUDY OF A RICINUS COMMUNIS L. (CASTOR OIL) DERIVATIVE AS A BIOCIDAL AGENT AND VISCOSITY REDUCER ON LEUCONOSTOC MESENTEROIDES IN THE SUGAR AND ALCOHOL INDUSTRIES

ABSTRACT Castor-oil, extracted from seeds of Ricinus communis L., is normally used in natura or in its modified form in the medical, pharmaceutical and industrial areas. One of its chemical derivates – Poliquilgerm® – has shown antifungal properties on Candida albicans, and bacteriostatic/bactericide effects on Escherichia coli reaching 99.9%. Considering these features, in the present study Poliquilgerm® was applied in cultures of Leuconostoc mesenteroides, a frequent contaminant bacterium of musts in the sugar and alcohol industries. This bacterium, when a contaminant of must, produces lactic acid as well as dextran, a polymer of glucose which may increase the viscosity of fluids in the operation. The present study evaluated the effect of different concentrations of Poliquilgerm® on viscosity produced by L. mesenteroides cultures under different conditions of various culture media, pH and temperature. A 20.56% decrease in viscosity was verified when 1.0% of the product was used, and bacterium growth inhibition after 20 hours in media with 1.0 and 0.2% of Poliquilgerm®. L. mesenteroides showed a higher growth rate in pH 6.0, at both 28 and 33º C, evidenced by greater biomass production. Also, in the culture media at this pH a greater decrease in viscosity percentages was verified at both concentrations used. The media with these same concentrations reached up to 100% decrease of UFC/mL after 24 hours in the presence of the product, observed by biomass quantification and confirmed by the Pour Plate technique.摘要 从蓖麻（Ricinus communis L.）种子中提取的蓖麻油（Castor-oil），通常以天然或改性形式应用于医疗、制药及工业领域。其一种化学衍生物——Poliquilgerm®，对白色念珠菌（Candida albicans）具有抗真菌活性，对大肠杆菌（Escherichia coli）的抑菌/杀菌效果可达99.9%。鉴于上述特性，本研究将Poliquilgerm®应用于肠膜明串珠菌（Leuconostoc mesenteroides）的培养体系中，该菌是糖与酒精工业中原料醪液的常见污染菌。该菌污染醪液时，会同时产生乳酸与葡聚糖（dextran，一种葡萄糖聚合物），后者会提升生产流程中流体的黏度。本研究评估了不同浓度的Poliquilgerm®在不同培养基、pH值及温度条件下，对肠膜明串珠菌培养体系所产生黏度的影响。实验结果证实：当添加1.0%的该产品时，体系黏度降低20.56%；在添加1.0%与0.2% Poliquilgerm®的培养基中，细菌生长在20小时后即受到抑制。肠膜明串珠菌在pH 6.0、28℃与33℃条件下均表现出更高的生长速率，体现为更高的生物量产量。同时，在该pH值的培养基中，两种测试浓度下的黏度降低百分比均更为显著。在添加上述浓度的培养基中，培养24小时后每毫升菌落形成单位（UFC/mL）的降低率可达100%，该结果通过生物量定量得以证实，并经倾注平板法（Pour Plate technique）进一步验证。