Bacterial respiration

C]Glucose Catabolism An actively respiring bacterial culture is briefly incubated with [1-14C] glucose, and the glycolytic and citric acid cycle intermediates are isolated. Where is the 14C in each of the intermediates listed below Consider only the initial incorporation of 14C, in the first pass of labeled glucose through the pathways. 

The subsequent fate of the assimilated carbon depends on which biomass constituent the atom enters. Leaves, twigs, and the like enter litterfall, and decompose and recycle the carbon to the atmosphere within a few years, whereas carbon in stemwood has a turnover time counted in decades. In a steady-state ecosystem the net primary production is balanced by the total heterotrophic respiration plus other outputs. Non-respiratory outputs to be considered are fires and transport of organic material to the oceans. Fires mobilize about 5 Pg C/yr (Baes et ai, 1976 Crutzen and Andreae, 1990), most of which is converted to CO2. Since bacterial het-erotrophs are unable to oxidize elemental carbon, the production rate of pyroligneous graphite, a product of incomplete combustion (like forest fires), is an interesting quantity to assess. The inability of the biota to degrade elemental carbon puts carbon into a reservoir that is effectively isolated from the atmosphere and oceans. Seiler and Crutzen (1980) estimate the production rate of graphite to be 1 Pg C/yr. 

One type of test measures the inhibition of respiration of bacterial cells on pieces of pig skin by the substance under test. Here, the factor of correlation between cell death and cessation of respiration should be borne in mind. 

Denitrification involves the sequential formation of nitrite, nitric oxide, and nitrous oxide. Two aspects of nitric oxide have attracted attention (a) chemical oxidation of biogenic nitric oxide to Nq, in the context of increased ozone formation (Stohl et al. 1996) and (b) the physiological role in mammalian systems (Feldman et al. 1993 Stuehr et al. 2004), in parasitic infections (James 1995), and in the inhibition of bacterial respiration (Nagata et al. 1998). Nitric oxide may be produced microbiologically in widely different reactions such as... 

Carpentier W, L De Smet, J Van Beeuman, A Brige (2005) Respiration and growth of Shewanella oneidensis MR-1 using vanadate as the sole electron acceptor. J Bacterial 187 3293-3301. 

Esteve-Nunez A, G Lucchesi, B Phillip, B Schink, JL Ramos (2000) Respiration of 2,4,6-trinitrotoluene by Pseudomonas sp. strain JLRll. J Bacterial 182 1352-1355. 

The most common pathogens in bacterial keratitis are Pseudomonas (including Pseudomonas aeruginosa) and other gram-negative rods, staphylococci, and streptococci. If the keratitis is related to the use of contacts, Pseudomonas is the most common cause followed by Serratia marcescens. For hospitalized infants and adults on respirators, Pseudomonas is the most common.19... 

Fig. 5.2. The photosynthetic membrane of a green sulfur bacterium. The light-activated bacte-riochlorophyll molecule sends an electron through the electron-transport chain (as in respiration) creating a proton gradient and ATP synthesis. The electron eventually returns to the bacteri-ochlorophyll (cyclic photophosphorylation). If electrons are needed for C02 reduction (via reduction of NADP+), an external electron donor is required (sulfide that is oxidised to elemental sulfur). Note the use of Mg and Fe.

Blum et al. (1998) isolated a bacterial strain Bacillus arsenicoselenatis from muds of Mono Lake, ahypersaline alkaline lake in northern California (see Section 24.2). Under anaerobic conditions in saline water, over an optimum pH range of 8.5-10, the strain can respire using As(V), or arsenate, as the electron acceptor, reducing it to As(III), arsenite. 

Resistance assays, general condition Implantation of syngeneic tumors, bacterial, viral, and parasitic infection Occurrence of sentinel disease (infection, neoplasia), growth indices, respiration rates, heart... 

Historically, respirometers have been used for wastewater biodegradability evaluation. More recently [52], a mobile on-line respirometer was proposed and tested for monitoring the activated sludge inhibition due to industrial discharges in a sewer network. A derived portable device called a Baroxymeter [53], based on monitoring the respiration of a bacterial culture by pressure measurements and using respiration inhibition as a toxicity alert, was proposed for the rapid detection of the toxicity effect of some toxic substances. 

Fortner et al. (2005) reported an inhibitory effect on bacterial growth due to the presence of fullerene nanoparticles at concentration > 4 mg/L, while recently the impact of C60 pollution on soil was described (Tong et al., 2007). The authors analyzed the soil respiration, as well as the enzymatic and the microbial activity... 

Stolz JF, Oremland RS. 1999. Bacterial respiration of arsenic and selenium. FEMS Microbiol Rev 23 615-27. 

A particularly important consequence of bioirrigation and bioturbation is the introduction of relatively 02-rich bottom water into the sediments. This enhancement in O2 supply is analogous to the aeration of soil by earthworms. Bioturbation can occur as deeply as 1 m below the sediment surface, but is most intense in the top 10 cm. The depth of O2 penetration is also strongly influenced by the flux of sedimenting POM. High accumulation rates of organic-rich particles can fuel bacterially mediated aerobic respiration supporting rates of O2 removal that exceed the benthic animals abilities to reaerate the sediments. In this case, anoxic conditions result. Since animals require O2, bioturbation does not occur in anoxic sediments. Thus, the effects of bioturbation are limited to the oxic portion of the sediments. 

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