| Biofilms are ubiquitous and important for bio-energy production, bio-remediation and bio-sensors in the field of environmental engineering; however, the understanding of biofilms is limited. In this research a new analytical tool, Spatial Analytical Microbial Imaging (SAMI), was developed to rapidly identify and locate bacteria species in a biofilm matrix nonspecifically, and to study microbial communities on a single cell level without disrupting cell structures. In the additional research, a highly active electron transfer (ET) and the extracellular ET extending phenomenon in a remediation biofilm was discovered and analyzed.;In additional research, the extracellular electron-transfer components extending far from the cells was observed at the 5-cyano-2, 3-ditolyl tetrazolium chloride (CTC) stained biofilm in an arsenate and sulfate reduction membrane biofilm reactor (MBfR). Three potential extracellular electron transfer mechanisms and abiotic CTC reduction were examined. Scanning electron microscopy provided evidence of nanowire structures. Clone-library analysis showed bacteria that are known to produce nanowires were among the dominant bacteria family in the biofilm. Furthermore, the sample spots with a high intensity of CTC labeled signals were similar in ET activity across the biofilm. These support the existence of a conductive biofilm, through which electrons were transferred to soluble electron acceptors located at a far distance from the bacteria cells.;Specific fluorescent dyes were used in SAMI to bind with bacteria nucleic acid nonspecifically. The 3D image data then was acquired through a confocal laser scan microscope and processed by specific software, which ultimately exported complex results such as cell guanine-cytosine (G-C) and adenine-thymine (A-T) content, cell counting, division and spatial distribution. In the case of a two bacteria species biofilm analysis, SAMI was verified by using the auto-fluorescence of Synechocystis sp. PCC6803. The accuracy was approximately 93% and statistically validated. SAMI also allowed monitoring the two species while growing in biofilm in a time sequence. The collected information can be used to improve the engineering process for harvesting more energy from the biofuel producing microbe Synechocystis sp. PCC6803. Comparing a mouse tumor cell line and a mouse normal cell line, SAMI also showed promise in the diagnosis of mammalian cancer cell lines. |
