Studies on the antimicrobial effects of microalgae extracts are commonly reported using algae biomass grown in sterile synthetic mineral medium and controlled laboratory conditions. However, variations in environmental conditions and culture medium composition are known to alter microalgae biochemical structure possibly affecting the type and concentrations of bioactive compounds with antimicrobial properties. In this work, solvent extracts of the microalgae Chlorella spp. were tested for antimicrobial effects against gram-positive and multidrug resistant pathogenic bacteria Staphylococcus hyicus, Enterococcus faecalis and Streptococcus suis. Microalgae was cultivated at field scale open pond reactor using raw swine wastewater as growth substrate. Dichloromethane or methanol were used to obtain the microalgae extracts. Characterization of the extracts by ultra-high performance liquid chromatography-quadrupole mass spectrometry revealed the presence of 23 phytochemicals with recognized antimicrobial properties. Bacteriostatic activity was observed in plating assays by formation of inhibition zones ranging from 7 to 18 mm in diameter. Only dichloromethane extracts were inhibitory to all three model bacteria. The minimum inhibitory concentration assessed for dichloromethane extracts were 0.5 mg mL⁻¹ for S. hyicus and E. faecalis and 0.2 mg mL⁻¹ for S. suis. Bactericidal effects were not observed using solvent-extracts at 2 or 5 mg L⁻¹. To the best of authors knowledge, this is the first report on the antimicrobial effects of Chlorella spp. extracts against Staphylococcus hyicus and Streptococcus suis. Overall, Chlorella spp. grown on swine wastewater contains several phytochemicals that could be further explored for the treatment of infections caused by antibiotic-resistant bacteria pathogens.

通常使用在无菌合成矿物培养基和受控实验室条件下生长的藻类生物质来研究微藻提取物的抗菌作用。然而，已知环境条件和培养基成分的变化会改变微藻生化结构，可能会影响具有抗菌特性的生物活性化合物的类型和浓度。在这项工作中，微藻小球藻的溶剂提取物。对革兰氏阳性菌和多重耐药病原菌金黄色葡萄球菌、粪肠球菌和猪链球菌的抗菌作用进行了测试. 使用生猪废水作为生长基质在田间规模的开放式池塘反应器中培养微藻。二氯甲烷或甲醇用于获得微藻提取物。通过超高效液相色谱-四极杆质谱法对提取物的表征表明存在 23 种具有公认抗菌特性的植物化学物质。通过形成直径为 7 至 18 毫米的抑菌圈，在平板试验中观察到抑菌活性。只有二​​氯甲烷提取物对所有三种模型细菌都有抑制作用。对二氯甲烷提取物评估的最小抑制浓度为 0.5 mg mL ^-1对S. hyicus和E. faecalis和 0.2 mg mL ^-1对猪链球菌. 使用 2 或 5 mg L ^{-1 的}溶剂提取物未观察到杀菌效果。据作者所知，这是关于小球藻抗菌作用的第一份报告。抗葡萄球菌和猪链球菌的提取物。总体而言，小球藻属。生长在猪废水上的植物化学物质含有多种植物化学物质，可以进一步探索这些植物化学物质用于治疗由耐抗生素细菌病原体引起的感染。