Bacterial biomass

The automated EXAMS model consists of a set of FORTRAN programs which calculates the fate, exposure and dissipation of the chemical from input environmental data such as 1) Global parameters (rainfall, irradiance, latitude), 2) Biological parameters (biomass, bacterial counts, chlorophyll), 3) Depths and in-lows, 4) Sediment characteristics, 5) Wind, 6) Evaporation, 7) Aeration, 8) Advective and turbulent interconnections, 9) Water flow, 10) Sediment flow, 11) pH and pOH, and 12) Temperature. Also characteristics of the chemical are taken into account such as hydrolysis photolysis, oxidation, biolysis, and volatility. 

SAQ 4.15 Use the data in the Resource Material to answer the following question. It is 1977. The bacterial SCP from methanol plant referred to in Table 4.9 does not produce protein at a price that competes with soya protein. By how much would the cost of methanol have to fall in order that the protein from such a plant can be produced competitively with soya protein You can assume i) that the SCP processes referred to in Tables 4.7 and 4.9 to 4.15 are of 2 x 10s tons annual capacity, ii) that yield on methanol is 0.5kg biomass per kg methanol, iii) bacterial SCP contains 60% protein. 

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. 

There are a wide variety of initial sources of NOs for the ice sheets, including bacterial emissions, biomass burning, photochemical reactions, and lightning. These are generally low-mid-latitude continental sources. This very complicated mixed source renders interpretations of ice-core NOJ" concentrations difficult. A further complication results from possible limitations on delivery of NOT to ice-core sites by atmospheric circulation, due to the large distance from... 

Molecular hydrogen plays a major role on the oxidation-reduction processes involved in bacterial energetics, as well as in the degradation and conversion of biomass related with all major elemental cycles. Hydrogenase has a key role on this process and catalyzes the reversible oxidation of dihydrogen, important in bacterial anaerobic metabolism ... 

A. Frostegard and E. Baath. The use of phospholipid fatty-acid analysis to e.stimatc bacterial and fungal biomass in soil, Biol. Eeiiil. Soll.s 22 59 (1996). 

F. T. Gillan and R. W. Hogg, A method for the estimation of bacterial biomass and community structure in mangrove-associated sediments, J. Microb. Methods 2 275 (1984). 

For anabolic reactions, which result in the production of new cells, it is important to know the approximate chemical composition of the biomass. The bacterial protoplasm comprises 75 to 80% water. The solid material is composed of several complex organic molecules, such as proteins, carbohydrates, and DNA. The mean composition of these molecules can be approximated by a relatively simple empirical formula, C60H87O23N12P, or in an even more simple form as C5H7O2N10.Numerous other elements such as sulfur, sodium, potassium, calcium, magnesium,... 

Degradation is often the result of the combined effect of chemical transformation and biodegradation. For example, the oxidation/reduction of complex hydrocarbons can produce simple compounds such as peroxides, primary alcohols, and monocarbocylic acids. These compounds can then be further degraded by bacteria, leading to the formation of carbon dioxide, water, and new bacterial biomass.19-35... 

As bioremediation proceeds, the bacterial population increases due to the growth of the biomass. Thus, although bacteria may be deficient at the beginning they do not usually need to be added after the startup. 

Generally, poly(3HB) can be produced discontinuously or continuously. To reach high biomass concentrations fed-batch processes are the method of choice. Continuous methods have only been occasionally used, but unfounded, as shown below. Comprehensive reviews on the current state of technical procedures have been given by Lee and Chang [103], Lee [99], Braunegg et al. [37], and Madison and Huisman [104]. Special conditions and approaches to maximize the exploitation of bacterial potentials with the two types of process regime are discussed below. 

R. eutropha is actually an autotrophic hydrogen-oxidizing bacterium which can also produce poly(3HB) from C02, H2, and 02 [34]. The critical factor in such autotrophic cultivation processes is to avoid possible gas explosions. Therefore, a recycled gas, closed circuit culture system equipped with several safety features was developed and the oxygen concentration in the substrate gas phase was kept below the lower limit for gas explosions. A bacterial biomass of 91.3 g 1 1 has been achieved and the poly(3HB) content reached up to 67% per cell dry weight under these oxygen-limited conditions [35]. 

The method of pure polymer recovery from the biomass prior to characterization can influence the molecular weight of the polymer significantly. Extraction of PHB-bacterial cells with organic solvents yields polymers with higher molecular weight compared to sodium hypochorite treatment [44-46]. Pretreatment of the biomass with a surfactant prior to hypochlorite digestion... 

Fig. 16.3 Replicated field trial in Wadenswil, Switzerland where higher bacteria biomass (expressed as microbial bound carbon (Cmic) was found in the organically managed orchard soils (crosses = organic squares = conventional, integrated) than in orchards managed according to integrated farming practice. Higher bacterial biomass was correlated with increased content of water-extractable calcium in soil samples...

Mullen et al. (1989) reported that Bacillus cereus, B. subtilis, E. coli and P. aeruginosa were able to sorb an average of 89% of the total Ag+ and 12-27% of the total Cd2+, Cu2+ and La3+ from a ImM solution. Using polyacrylamide-entrapped cells of Brevibacterium sp strain PBZ, Simine et al. (1998) measured a sorption capacity of 40 mg g-1 and 13 mg g-1 dry biomass for Pb and Cd, respectively. Hall et al. (2001) isolated two bacterial strains of P. syringae that were tolerant to 1000 mg L-1 Cu. Similarly, Amoroso et al. (2001) were able to obtain Streptomyces spp. strains R22 and R25 with a high tolerance to Cr from sediments of the Sail River, Argentina. The cells of R22 and R25 could accumulate 10.0 and 5.6 mg Cr g-1 dry weight, respectively, from a concentration of 50 mg Cr mL 1. Cell fractionation studies with strain R22 showed that most of the chromium... 

Savvaidis I, Hughes M, Poole R (1992) Differential pulse polarography a method of directly measuring uptake of metal ions by live bacteria without separation of biomass and medium. FEMS Microbiol Lett 92 181-186 Savvaidis I, Hughes MN, Poole RK (2003) Copper biosorption by Pseudomonas cepacia and other strains. World J Microbiol Biotechnol 19 117-121 Scott JA, Palmer SJ (1988) Cadmium biosorption by bacterial exopolysaccharide. Biotechnol Lett 10 21-24... 

The qCC>2 is often used as an indicator of whether the microbial biomass is under stress. In general, factors that decrease the size of the microbial biomass tend to increase qC02. That is, factors that cause stress to the microbial community tend to reduce its size. Other factors could also contribute to an increased qC02. For example, bacterial communities are less efficient at converting substrate C into cellular C than fungi (Sakamoto and Oba 1994) so a change in the composition of microbial biomass can alter qC02 values. 

Ros M, Pascuala JA, Garciaa C, Hemandeza MT, Insam H (2006) Hydrolase activities, microbial biomass and bacterial community in a soil after long-term amendment with different composts. Soil Biol Biochem 38 3443-3452 Rovira P, Vallejo VR (2002) Labile and recalcitrant pools of carbon and nitrogen in organic matter decomposing at different depths in soil an acid hydrolysis approach. Geoderma 107 109-141... 

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