The bio-industrial application of microalgae has gained much attention in recent years. One of the challenges in this field is to lower the cultivation and harvest costs and to achieve the steady productivity. To address this, new systems have been proposed, in which the products are extracted without killing the algal cells. These non-destructive extraction systems are called “milking.” Some of the milking systems reported so far are continuous processes where culturing and milking occur simultaneously, and the others are a periodic process where cells are cyclically cultured and milked. These systems are based on the organic solvent extraction of non-polar products, such as lipids, terpenes, and carotenoids. However, a special facility required for handling organic solvents increases the costs and solvents lost during milking need to be recouped. In this study, we examined a solvent-free method, based on mechanical milking using a shearing disperser (glass homogenizer). We cultured the N₂-fixing filamentous cyanobacteria, Tolypothrix sp. PCC7601 in non-sterile agricultural water and performed long-term (87 days) milking cycles to harvest the extracellular carbohydrates and phycobiliproteins. As a result, the productivity of extracellular carbohydrates and the cell densities remained constant throughout the milking cycle, yielding 90–140 mg/L of extracellular carbohydrates every 3 weeks. Our results demonstrated that mechanical milking is a practical and effective method that can be used to harvest products from algae steadily.

近年来，微藻类在生物工业中的应用受到了广泛关注。该领域的挑战之一是降低耕种和收获成本并实现稳定的生产率。为了解决这个问题，已经提出了新的系统，其中提取产物而不杀死藻类细胞。这些无损提取系统称为“挤奶”。迄今报道的一些挤奶系统是连续过程，在该过程中同时进行培养和挤奶，而另一些是周期性过程，在该过程中细胞被周期性地培养和挤奶。这些系统基于非极性产物（例如脂质，萜烯和类胡萝卜素）的有机溶剂萃取。但是，处理有机溶剂所需的特殊设施会增加成本，并且需要弥补挤奶过程中损失的溶剂。在这项研究中，我们研究了一种无溶剂方法，该方法基于使用剪切分散器（玻璃均质器）的机械挤奶。我们培养了N₂ -定影丝状蓝藻，Tolypothrix SP。PCC7601在非无菌农业用水中进行了长期（87天）挤奶循环，以收获细胞外碳水化合物和藻胆蛋白。结果，在整个挤奶周期中，细胞外碳水化合物的生产率和细胞密度保持恒定，每3周产生90-140 mg / L的细胞外碳水化合物。我们的结果表明，机械挤奶是一种实用且有效的方法，可用于稳定地从藻类收获产品。