Application of desalination technology for deep ocean water (hereinafter, DOW) to the tap water supply business has been verified. DOW is advantageous for desalination because it has less suspended solids and less chlorine consumption than surface seawater (hereinafter, SOW). In addition, the amount of DOW is huge compared to the water available on land (river water, lake water, etc.) used in most of the current tap water systems. In addition, the water temperature and quality of DOW are stable, and its water quality is extremely clean as well as no restriction of water rights for using. Possible disadvantages are locations where DOW can be taken are generally far from urban areas, which are large-scale consumption areas, and the cost of desalination of DOW is higher than that of current tap water cleaning process using river and reservoir waters. However, the cost difference is narrowing with the progress of technology, and it is presumed that the cost will be further reduced if freshwater production is used as a by-product of ocean thermal energy conversion. Accordingly, it is considered that DOW desalination technology can greatly contribute to solving various problems of water treatments in the current tap water supply business.

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Regarding the characteristics of deep seawater (DSW), one of the resources that matches the concept of sustainable development goals (SDGs), is that it contains various kinds of useful substances for human life unlike solar, wave, wind and geothermal resources. In this study, microorganisms from DSW which have not been fully utilized were the focus. Especially, lactic acid bacteria which have been used in the health care industry were chosen among them. Four isolates were randomly selected from 19 lactic acid bacteria candidates isolated from DSW at Izu-Akazawa and were identified species by 16S rDNA sequence analysis. As a result, all of four isolates were identified as Lactiplantibacillus plantarum. There was a slight difference in physiological and biochemical characteristics between the isolates from DSW and the type strain of L. plantarum. Furthermore, there was also a little difference in enzyme production between the isolates and the type strain. Then, it was suggested that the culture supernatant of the isolate BF1‒13 increased expression of tight junction related proteins (TJs) and aquaporin 3 (AQP3) genes in vitro using normal Madin-Darby canine kidney (MDCK) cells. On the other hand, there was no effect in the supernatant of the type strain.

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