ABSTRACT
Microcystins (MCs) are the most potent toxins that can be produced by cyanobacteria in drinking water supplies. This study investigated the abundance of toxin-producing algae in 11 drinking water treatment plants (DWTPs). A total of 26 different algal taxa were identified in treated water, from which 12% were blue green, 29% were green, and 59% were diatoms. MC levels maintained strong positive correlations with number of cyanophycean cells in raw and treated water of different DWTPs. Furthermore, the efficiency of various algal-based adsorbent columns used for the removal of these toxins was evaluated. The MCs was adsorbed in the following order: mixed algal-activated carbon (AAC) ≥ individual AAC > mixed algal powder > individual algal powder. The results showed that the AAC had the highest efficient columns capable of removing 100% dissolved MCs from drinking water samples, thereby offering an economically feasible technology for efficient removal and recovery of MCs in DWTPs.
Subject(s)
Bacterial Toxins/isolation & purification , Carbon/chemistry , Drinking Water/chemistry , Marine Toxins/isolation & purification , Microcystins/isolation & purification , Water Pollutants/isolation & purification , Water Purification/methods , Bacterial Toxins/analysis , Cyanobacteria , Cyanobacteria Toxins , Environmental Monitoring , Marine Toxins/analysis , Microcystins/analysis , Water Pollutants/analysisABSTRACT
Spirulina (SP) (Arthrospira platensis; previously Spirulina platensis) is a filamentous blue-green microalga (cyanobacterium) with potent dietary phytoantioxidant and anticancerous properties. We investigated the chemopreventive effect of SP against 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat breast carcinogenesis, and further studied its underlying mechanisms of action in vitro. Remarkably, SP cleared DMBA-induced rat mammary tumors, which was clearly confirmed by morphological and histological methods. SP supplementation reduced the incidence of breast tumors from 87% to 13%. At the molecular level, immunohistochemical analysis revealed that SP supplementation reduced expression of both Ki-67 and estrogen α. More interestingly, molecular analysis in the in vitro experiments indicated that SP treatment inhibited cell proliferation by 24 hours, which was accompanied by increased p53 expression, followed by increased expression of its downstream target gene, Cdkn1a (alias p21 or p21(Waf1/Cip1)). In addition, SP increased Bax and decreased Bcl-2 expression, indicating induction of apoptosis by 48 hours after SP treatment. To our knowledge, this is the first report of in vivo chemopreventive effect of SP against DMBA-induced breast carcinogenesis in rat, supporting its potential use in chemoprevention of cancer.
