• Environmental Engineering Research
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• v.15 no.2
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• pp.71-78
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• 2010

To understand the effects of acclimation schemes on the formation of anode biofilms, different electrical performances are characterized in this study, with the roles of suspended and attached bacteria in single-chamber microbial fuel cells (MFCs). The results show that the generation of current in single-chamber MFCs is significantly affected by the development of a biofilm matrix on the anode surface containing abundant immobilized microorganisms. The long-term operation with suspended microorganisms was demonstrated to form a dense biofilm matrix that was able to reduce the activation loss in MFCs. Also, a Pt-coated anode was not favorable for the initial or long-term bacterial attachment due to its high hydrophobicity (contact angle = $124^{\circ}$), which promotes easy detachment of the biofilm from the anode surface. Maximum power ($655.0\;mW/m^2$) was obtained at a current density of $3,358.8\;mA/m^2$ in the MFCs with longer acclimation periods. It was found that a dense biofilm was able to enhance the charge transfer rates due to the complex development of a biofilm matrix anchoring the electrochemically active microorganisms together on the anode surface. Among the major components of the extracellular polymeric substance, carbohydrates ($85.7\;mg/m^2_{anode}$) and proteins ($81.0\;mg/m^2_{anode}$) in the dense anode biofilm accounted for 17 and 19%, respectively, which are greater than those in the sparse anode biofilm.

• Journal of fish pathology
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• v.30 no.2
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• pp.97-105
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• 2017

Parasitic leeches could directly (through causing poor growth, anemia and wound in the fish) and indirectly (by predisposition of the fish to secondary bacterial and fungal infections) affects their hosts. In the present study, fishes that were attacked by leeches in natural and experimental environment were studied. Pathologic samples were obtained from damages at the site of leech bite, as well as kidney and liver of the fish. Histopathological examination revealed numerous lesions at the site of leech bite including tissue demolition, detachment at the site of leech bite in the epidermis of epithelial tissue in the skin, destructed nucleus in epithelial cells of the skin plus necrosis in the damaged skin and weak inflammatory penetration to acute necrotic damages along with piercing dermis layer. Pathologic lesions in the kidney included some changes such as proliferation by increasing glomerular cells and membrane cells in capillary vein of the kidney, blood cell necrosis in kidney with infiltration of white blood cells mainly mononuclear and less polymorphonuclear which are the symptoms of anemia due to blood feeding and sucking by leeches. There was also a chronic kidney infection probably originated from another part of body such as skin. Moreover, leeches caused hemorrhagic anemia due to blood consumption of the hosts, which led to observation of immature red blood cells. Also results showed that diseases induced by leeched in fish could be acute or chronic, which depends on size of fish, species of leech and severity of infection.