Microbial processes incubations

Aliphatic-Garboxylics. There are only two herbicides present in this class, trichloroacetate [76-03-9] (TCA) and dalapon [75-99-0]. These are used primarily for the selective control of annual and perennial grass weeds in cropland and noncropland (2,299). Dalapon is also used as a selective aquatic herbicide (427). Dalapon and TCA are acidic in nature and are not strongly sorbed by sods. They are reported to be rapidly degraded in both sod and water by microbial processes (2,427). However, the breakdown of TCA occurs very slowly when incubated at 14—15°C in acidic sods (428). Timing not only accelerates this degradation but also increases the numbers of TCA-degrading bacteria. An HA has been issued for dalapon, but not TCA (269). 

Cleveland, C.C., Townsend, A.R. and Schmidt, S.K. (2002) Phosphorus limitation of microbial processes in moist tropical forests evidence from short-term laboratory incubations and field studies. Ecosystems 5, 680-691. 

This chapter provides an overview of microbial processes involved in the degradation of natural and synthetic fibers, starting with an introduction of relevant terminology. It discusses the methods used to assess the microbial breakdown of fibers and gives examples of the sources of microbial communities and the methods of incubation that are used in these studies. Finally, it provides examples of the types of bonds that are susceptible to microbial attack. 

It is necessary to estabUsh a criterion for microbial death when considering a sterilization process. With respect to the individual cell, the irreversible cessation of all vital functions such as growth, reproduction, and in the case of vimses, inabiUty to attach and infect, is a most suitable criterion. On a practical level, it is necessary to estabUsh test criteria that permit a conclusion without having to observe individual microbial cells. The failure to reproduce in a suitable medium after incubation at optimum conditions for some acceptable time period is traditionally accepted as satisfactory proof of microbial death and, consequentiy, stetihty. The appHcation of such a testing method is, for practical purposes, however, not considered possible. The cultured article caimot be retrieved for subsequent use and the size of many items totally precludes practical culturing techniques. In order to design acceptable test procedures, the kinetics and thermodynamics of the sterilization process must be understood. 

This is an important parameter particularly for naturally occurring mixed cultures of organisms in the natural environment temperature may result in important changes in the composition of the microbial flora as well as on the rates for different processes. An illustrative example of its importance includes the following. An anaerobic sediment sample was incubated with... 

The second patent describes the use of a microbial mixed culture (Hansenula sydowiorum, Hansenula ciferrii, Hansenula lynferdii, and/or Cryptococcus albidus) in coal desulfurization [160], In this process, the raw mined coal is ground to a particle size smaller than 200 mesh forming a slurry with water, at a solids concentration of less than 40wt%. The bacterial cultures are then inoculated into the feedstock slurry. An incubation step is carried out at a temperature near 25°C and at a pH close to neutral. The highest removal achieved was in the range of 46% S removal. 

Recent work in our laboratories has confirmed the existence of a similar pathway in the oxidation of vindoline in mammals (777). The availability of compounds such as 59 as analytical standards, along with published mass spectral and NMR spectral properties of this compound, served to facilitate identification of metabolites formed in mammalian liver microsome incubations. Two compounds are produced during incubations with mouse liver microsome preparations 17-deacetylvindoline, and the dihydrovindoline ether dimer 59. Both compounds were isolated and completely characterized by spectral comparison to authentic standards. This work emphasizes the prospective value of microbial and enzymatic transformation studies in predicting pathways of metabolism in mammalian systems. This work would also suggest the involvement of cytochrome P-450 enzyme system(s) in the oxidation process. Whether the first steps involve direct introduction of molecular oxygen at position 3 of vindoline or an initial abstraction of electrons, as in Scheme 15, remains unknown. The establishment of a metabolic pathway in mammals, identical to those found in Strep-tomycetes, with copper oxidases and peroxidases again confirms the prospective value of the microbial models of mammalian metabolism concept. 

Excluding cosmetic defects, all units that would be procedurally discarded during production shall not be incubated. The reason for discarding shall be documented. It is important that the procedures for excluding units be sufficiently specihc to ensure consistency between process simulation runs and normal operations. Incubation of nonintegral units would introduce a risk for microbial contamination (e.g., during transport to the microbiology lab or... 

The rate of methylation of mercury in anaerobically incubated estuarine sediments proved to be inversely related to salinity (267) this is consistent with results reported in Section II,A. Methylmercuric ion forms in sediments upon addition of HgCl2, with a lag phase of 1 month (268). Biomethylation by lake water columns and by sediments coincided, apparently being related to overall microbial activity, and showed periodic fluctuations (269). Topping and Davies have demonstrated that mercury can be methylated in the water column of a sea loch (270). As has previously been noted, tin compounds can be methylated by sediments (121-124), and this is also true for lead (134-136, 271). The relative proportions of biotic and abiotic methylation processes for such systems still remain to be determined. 

Figure 8. Schematic diagram of Continual Measuring System for BOD. 1. Sensor unit 2. Recorder unit 3. Data processing unit 4. Flow line selector unit 5. Sampling unit 6. Amplifier 7. Microbial sensor 8. Pump 9. Incubator 10. Flow meter 11. Air pump ...

Enzymatic posthydrolysis enabled monosaccharide recoveries in the range usually attained for other feedstocks to be obtain (17,18). The higher recoveries were obtained with Celluclast 1.5L and Viscozyme L, with arabinose recoveries close to 75%, xylose recoveries of 63%, and close to total glucose recovery. Furthermore, no additional production of microbial inhibitors occurs during the enzymatic step, with the exception of acetic acid. However, the long incubation time and catalyst costs may constitute important constraints for the near-term implementation of an enzyme-based conversion process to the conversion of OCL to monosaccharides. 

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