RESUMO
A microbial fuel cell (MFC), a novel technology, is a biochemical catalyzer system that can convert the chemical energy of materials to bioelectric energy. This system can serve as a unique device for the treatment of wastewater. Based on this knowledge, we decided to study the bioenergy production ability of Actinomycete and microbial isolates in industrial glass factory wastewater as the decomposers of organic materials in this wastewater and the generation of Voltage and current in two batches and fed-batch conditions. At the most favorable condition maximum of 1.08 V (current 3.66 mA and power density 2.88 mW/m2), 81.2% chemical oxygen demand was obtained for a fed-batch system. Also, the outcomes of MFC's essential parameters, for example, pH and TDS, were studied before and after the performance of MFC. The results showed a significant decrease after the operation of the MFC. To realize which Actinomycete were the most powerful bioelectric microorganism, the growth curve and electricity performance of three kinds of Actinomycete was selected. Results showed that the C2 would be more potent because its Voltage of 0.224 V and current of 1.187 mA possessed by it would result in an excellent power density of 141.42 mW/m2.
RESUMO
Background: Mycobacterial infections in fish is largely chronic to subacute in nature and affects fishes in fresh water, brackish water and salt water. In addition to their known infectivity to fishes, aquatic mycobacteria pose significant zoonotic concerns. Due to the zoonotic character of the disease, increasing importance of aquariology, and lack of any clinical signs in early steps of mycobacteriosis, present study was undertaken to analyze the distribution of mycobacteria in diseased and apparently healthy ornamental fish from some local aquarium fish shops in four different cities in Iran by culture and Ziehl-Neelsen staining. Materials, Methods & Results: One hundred and one fresh water aquarium fish of 22 species from some local shops in four cities in Iran were examined. Before decontamination, smears of homogenized samples stained with Ziehl-Neelsen. For bacterial culture, samples were inoculated on Lowenstein-Jensen medium. Culture plates were examined daily for four weeks. The rate of growth at different temperature, colony morphology and pigmentation were evaluated for species identification. Among 79 moribund fish examined, 16 individuals were positive for acid fast rods at microscopic examination. Seven fish out of 22 apparently healthy individuals also gave positive microscopic results. Using the culture method, 29 and 10 Mycobacterium isolates were obtained from moribund and healthy fish. The following Mycobacterium species were isolated from unhealthy fish: Mycobacterium fortuitum, M. marinum, and M. smegmatis. The number of different species of Mycobacterium from apparently healthy fish was: M. fortuitum (one fish), M. marinum (one fish), M. terrae (one fish) and M. flavescens (one fish). Discussion: Based on the results in both moribund and apparently healthy fish examined, culture examination showed more mycobacteria than Ziehl-Neelsen staining detection. Lower proportion of Ziehl-Neelsen positive results compared with culture method was reported in aquarium fish in Slovania. Using positive microscopic results, 13 isolates were obtained where as 29 samples gave positive culture results for mycobacteria. Similar result was also observed in clinically healthy ornamental fish and their aquarium environment. The identification of mycobacteria by Ziehl-Neelsen staining is a traditional method. However, acid-fast bacilli may not always be found through direct microscopy because the destruction of mycobacteria or their low number may sometimes happen. Culture examination is a more sensitive method than direct microscopy. However, killing of mycobacteria caused by host defense mechanisms, a low number of viable mycobacteria in the tissue, or by destruction of the mycobacteria during the preparation of the sample could result in negative cultivation results. Species of Mycobacterium identified in unhealthy fish were M. fortuitum, M. marinum and M. smegmatis. High frequency of identifying M. fortuitum and M. marinum (6 out of 7) in the samples provide more evidence that these species are common Mycobacterium species to be found in diseased aquarium fish. Numerous studies showed the common isolation of these two species from aquarium fish. M. marinum infection may be an occupational hazard for certain professionals such as pet shop workers. Many infections may also occur in fish fanciers who keep an aquarium at home. Less common than M. marinum, M. fortuitum is also capable of infecting human. In this study, the occurrence of M. marinum and M. fortuitum in both unhealthy and apparently healthy aquarium fish shows the importance of recognizing fish mycobacteriosis in order to prevent their transmission to human.