Inoculum Quantity

The volume of inoculum sample is not always indicated (Table 6). The quantity of inoculum represents a compromise on the one hand, a small amount of inoculum (in dry weight) does not bias the measurement because the microbial carbon proportion versus the sample carbon is low on the other hand, a large amount of inoculum accelerates the course of degradation and makes the measurement more repeatable (ASTM D 5271-93). From one test to another, the number of Colony-Forming Units/ml (CFU/ml) varies from 104 to 108. 

The problem with this method is it is time-consuming (24 h to get an answer), requires skilled operators and gives only the viable biomass (not the active one). 

Number Origin A1 F2 D3 Storage Inoculation Quantity Cellular density 

5209-92 municipal sewage weeks without nutrients of degradation medium Optional 

5271-93 treatment plant Not specified Sewage sludge 0.1 VSS 1.0 g/L Not specified 

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Experiments were carried out by varying the amount of inoculum (10, 15 and 20 % v/v) to determine the optimal quantity which ensures a steady growth. The time course of growth of the cell suspensions, inoculated with the corresponding amount of inoculum was traced by day-to-day determining the yield of dry cell biomass (7), while the time course of biosynthesis of extracellular polysaccharides was followed by their daily determination, using the carbazole method (9). 

On the other hand, with cell suspensions synthesizing a considerable amount of polysaccharides, the excessive quantity of inoculum can lead to intensive aggregation before the maximum in the biomass synthesis is reached. 

Starting from an inoculum (X at t=0) and an initial quantity of limiting substrate, S at t=0, the biomass will grow, perhaps after a short lag phase, and will consume substrate. As the substrate becomes exhausted, the growth rate will slow and become zero when substrate is completely depleted. The above general balances can be applied to describe the particular case of a batch fermentation (constant volume and zero feed). Thus,... 

Known quantities of the mineral slurry were placed in two sterile containers and inoculated with the inoculum. The slurries were thoroughly mixed and 50 ml aliquots were dispensed into sterile, stoppered flasks or capped bottles. 

Blok, J. and M. Booy. 1984. Biodegradability test results related to quality and quantity of the inoculum. Ecotox. Environ. Safety 8 410-422. 

Figures 9.2 and 9.3 show schemes that illustrate inoculum development from the cryotubes to production scale for suspension and adherent cells, respectively. In these hypothetical process schemes, the expression production bioreactor is used arbitrarily for any of the types of bioreactor presented in the next section of this chapter. In general, different flasks and several intermediate bioreactors are used for cell propagation to reach the quantity of cells necessary to inoculate the production bioreactor. The number of propagation steps is a function of the final scale of the production bioreactor.

Starting from an inoculum, Cxi at t = 0, and an initial quantity of limiting substrate Csi at t = 0, the biomass will grow after a short lag phase and will consume substrate. The growth rate slows as the substrate concentration decreases, and becomes zero when all the substrate has been consumed. Simultaneously, the biomass concentration initially increases slowly, then faster until it levels off when the substrate becomes depleted. Figure 11-21 shows a sketch of a batch fermenter. 

Wet-millers avoid purchasing obviously moldy com, but mycotoxins can be present in com with low levels of inoculum. Blending moldy com with uncontaminated com, as occurs in the market channel, results in contamination of larger quantities of com than originally existed from the field. 

In our further study we investigated effects of various numbers of virulent (strain C) and avirulent (strain A) E. coli on serum microbiostasis. Bovine serum was distributed in 1-ml quantities into small screw-topped tubes and was infected with various numbers of strain A or strain C bacteria. After 12- and 24-hr incubation at 37 °C, samples of infected sera were plated on IPAM. Numbers of bacteria were determined by counting bacterial colonies on plates after 12-hr incubation. Results showed that bovine serum inhibited bacilli of avirulent strain A if the inoculated serum contained less than 12,000 bacilli per 1 ml of serum. Larger inocula of strain A multiplied in serum but at a slower rate than in broth medium (Table III). Bacteria of virulent strain C overcame the iron starvation in bovine serum even when serum was inoculated with as few as 100 cells/ml of serum. The results of this study showed that the rate of bacterial multiplication in bovine serum is determined partly by bacterial numbers in the inoculum. Small inocula of virulent and avirulent bacteria were more inhibited than large inocula. The growth of even minute inocula of virulent bacteria in bovine serum... 

Examples of commonly used bioseparations include sedimentation, coagulation, and filtration. The scale of operation for such bioseparation processes is considerable, because of the volumes of effluent which are processed and the throughputs required. Proprietary aerobic digesters such as the Deep Shaft process may use centrifugation to recover biomass from the treated effluent for recycle as an inoculum for the digester or to reduce the quantity of water before sending the solid material either to incineration or land fill. 

Irregular eyelid margins or function, irregular blinking, disturbed ocular surfece innervation, or abnormal tear film may compromise the epithelial surface. When an inoculum of sufficient quantity invades the conjimctiva, over-colonization by the infectious organism may result either from overwhelming normal flora or because the antimicrobial capabilities of the tear constituents have been exceeded. 

The monitoring and control of the fermentation process should be reported in detail. Parameters to be addressed include the media preparation and sterilization, inoculation procedures, and the fermentation process. Provide a detailed description of the media composition, the method for its sterilization (temperature and duration), and the pH after sterilization. The inoculation stage description should include quantity (by volume percent) and age of the inoculum to be used, as well as information on the morpho logical stage of the mycelium, if this parameter is controlled. The fermentation stages should be characterized by duration, temperature, pH, aeration rate (volume of air per volume of... 

Table 6. Preparation, storage and quantity of inoculum for standard tests... 

All standard test metho ds in liquid conditions are based on respiratory tests with a diversity of methodologies measurement of oxygen consumption is easily achieved (i. e., closed bottles with DBO meter), whereas determination of the carbon dioxide concentration requires costly equipment. Moreover, inoculum shows huge variability (several sources, treatments and quantities), causing variability in the results. The test sets that combine various types of controls (blank, sterile, toxicity) are not the same from one standard test to another and are sometimes open to criticism in their present form. Finally, as seen in Table 8, there is not common agreement between the standardization committees about the threshold for... 

Table 2 presents a comparison of the fermentation parameters used in the framework of this study by the multi-layer-packed bed reactor and data from experiments conducted in flasks and in enamel metallic trays using the same substrate and the same strain in passive aeration. It is evident that in flasks, xylanase production is higher than in the multi-layer-packed bed reactor and in the enamel metallic trays. A major difference in these three systems tested is the depth (bed height) of the fermented soya oil cake. Indeed, the production requires an appropriate thickness of medium for the microbial growth, the complete colonization of the medium, and not sporulation of the strain. A great quantity of inoculum enhances slightly the production. However, we think that it is not the best solution to improve the production. Indeed, with a low quantity of inoculum and an appropriate depth of medium, the entire... 

Table 1 Xylanase production in the multi-layer-packed bed reactor with a great quantity of inoculum (Io spores/gram of soya oil cake).

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