405 nm and 450 nm Photoinactivation of Saccharomyces cerevisiae
405 nm and 450 nm Photoinactivation of Saccharomyces cerevisiae
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DOI：
10.1556/1886.2018.00023
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发表时间：
2018-12-01
影响因子：
2.2
通讯作者：
Hessling, M.
中科院分区：
文献类型：
--
作者：
Hoenes, K.;Hess, M.;Hessling, M.
在许多研究中，用可见光对细菌进行光灭活已有报道。约405纳米的辐射被内源性卟啉吸收，并产生活性氧物种，从内部摧毁细菌。450-470 nm波段的蓝光也表现出抗菌作用，但比405 nm辐射弱，而且涉及的光敏剂还不清楚，尽管可能的候选者是黄素和卟啉。为了测试可见光是否能灭活真菌，并阐明其作用机制，用紫光和蓝光对模式生物酿酒酵母(DSM编号70449)进行了照射。405 nm和450 nm的平均照射剂量分别为182 J/cm(2)和526 J/cm(2)。然而，即使是强照射的培养物也几乎没有发现任何染色的酿酒酵母细胞，这表明细胞膜是完整的，从而证明了先前怀疑的至少对于所研究的菌株在可见光灭活过程中细胞膜破坏的机制。为了鉴定潜在的真菌光敏剂，测定了酵母细胞裂解物的吸收和荧光。光谱吸收和荧光结果表明，原卟啉IX在405 nm辐射下是最重要的光敏剂。对于450 nm的辐射，核黄素和其他黄素可能是主要的光敏剂候选，因为在该波长下，卟啉不起显著作用。在该菌株的光谱数据中没有发现其他光敏剂参与的证据。
Photoinactivation of bacteria with visible light has been reported in numerous studies. Radiation around 405 nm is absorbed by endogenous porphyrins and generates reactive oxygen species that destroy bacteria from within. Blue light in the spectral range of 450-470 nm also exhibits an antibacterial effect, but it is weaker than 405 nm radiation, and the photosensitizers involved have not been clarified yet, even though flavins and porphyrins are possible candidates.There are significantly fewer photoinactivation studies on fungi. To test if visible light can inactivate fungi and to elucidate the mechanisms involved, the model organism Saccharomyces cerevisiae (DSM no. 70449) was irradiated with violet (405 nm) and blue (450 nm) light. The mean irradiation doses required for a one log reduction of colony forming units for this strain were 182 J/cm(2) and 526 J/cm(2) for 405 nm and 450 nm irradiation, respectively.To investigate the cell damaging mechanisms, trypan blue staining was performed. However, even strongly irradiated cultures hardly showed any stained S. cerevisiae cells, indicating an intact cell membrane and thus arguing against the previously suspected mechanism of cell membrane damage during photoinactivation with visible light at least for the investigated strain. The results are compatible with photoinactivated Saccharomyces cerevisiae cells being in a viable but nonculturable state.To identify potential fungal photosensitizers, the absorption and fluorescence of Saccharomyces cerevisiae cell lysates were determined. The spectral absorption and fluorescence results are in favor of protoporphyrin IX as the most important photosensitizer at 405 nm radiation. For 450 nm irradiation, riboflavin and other flavins may be the main photosensitizer candidates, since porphyrins do not play a prominent role at this wavelength. No evidence of the involvement of other photosensitizers was found in the spectral data of this strain.