Bacteria oxygen requirement

Obligate aerobe Bacteria which require the presense of oxygen, such as Pseudomonas flourescens. A few strains of this species are capable of utilizing nitrate to allow anaerobic respiration. 

Peroxidases from saliva, crevicular fluid, bacteria, and fungi may contribute to this reaction in caries lesions. Although deeper layers of the carious microflora are assumed to be anaerobic, the oxygen required for the reaction may reach the deeper parts of the plaque via oxygen channels (Marquis, 1995). Lactobacilli, however, cause browning of dentin in the absence of tyrosinase (Dreizen et ah, 1957). 

Biochemical Oxygen Demand (BOD) The amount of oxygen required by bacteria stabilize decomposable organic matter under aerobic conditions. 

Any of the methods used to dismpt bacteria are successful when applied to archaeal cells. The only qualifier is that conditions used during breakage take into account the peculiar properties of archaeal proteins (e.g., sensitivity to oxygen requirement for high salt concentrations). 

Typically, this additional biological step is carried out in a pachuca, a cone-bottomed column familiar to the mining industry. Ground or milled ore, mixed with the aqueous bacterial solution, is introduced into the top of the column, and air is injected at the base. The injected air serves a number of functions it maintains the solid in suspension, it mixes the solid with liquid— giving a three-phase gas/liquid/ solid system—and it provides the oxygen and carbon dioxide required by the bacteria. The bacteria also require a feed of nitrogen and phosphorous, which can be added to the colunm if they are not indigenous to the ore. 

Aerobic bacteria complete most of the petroleum bioremediation applications, particularly those above the groundwater table. Aerobes are those bacteria that require an oxygen source as their TEA. Conversely, anaerobic species require the absence of oxygen (anoxic conditions) for their respiration. In situ anaerobic bioremediation is typically only conducted in the saturated zone because of the difficulty in maintaining a strict anaerobic environment. In some instances, facultative anaerobes are utilized because they can alter the respiration to be metabolically active under both anaerobic and aerobic conditions. As such, the type of TEA available will dictate the metabolism and subsequent degradation mode. The most common TEAs used for bioremediation are listed in Table 2. Careful selection of microbe-TEA combinations can enable a specific degradation pathway to facilitate cometabolism and prevent undesired degradation by-products. 

Until recently it has been assumed that sulfate-reducing bacteria always required a strictly anaerobic environment. These environments are found in deep coastal-plain areas, oil-field brines, and in black (organic-rich), waterlogged soils and muds associated with rivers, lakes, and swamps. Sulfate reduction has also been observed in local microenvironments such as those created by the decay of a fish buried in otherwise oxidizing sediments (Berner 1971). Contrary to traditional belief, active sulfate reduction has also been observed in the presence of dissolved oxygen in the photosynthetic zone of microbial mats (Canfield and Des Marais 1991). 

One of the most important characteristics of wastewater is the amount of oxygen required to stabilize it. This quantity is called the oxygen demand, and is determined either as biological oxygen demand (BOD) or chemical oxygen demand (COD). BOD is the quantity of oxygen required to stabilize wastewater in the presence of bacteria that consume the chemical pollutants and oxygen in the sample and can be determined by Standard Method 5210 (Standard Methods, 1998). 

The activated sludge process uses an enriched bacteria suspension to which normal or 02-enriched air is added. Surface aerators blow the oxygen required for microbiological decomposition into the water of the activated sludge tank. A downstream settling tank is used to separate and prethicken the bacteria suspension. The following criteria are essential for smooth operation of the facility... 

Biochemical oxygen demand The quantity of oxygen required by bacteria to metabolize organic matter in water. 

The biochemical oxygen demand (BOD) is a crucial environmental index for determining the relative oxygen requirements of wastewater, effluents, and polluted water. It refers to the quantity of oxygen required by bacteria and other microorganisms in the biochemical degradation and transformation of organic matter under aerobic conditions. The BOD... 

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