Carbon sources, bacteria

It is important to clarify that all the studies summarized in Figures 9.3 and 9.4 correspond to batch processes, and to highlight that the maximum biosurfactant concentration is close to 1 % (10 g/1) for all the different combinations of carbon sources, bacteria species and strains. In most of these studies, the biosurfactant is separated by precipitation at a pH of 2, followed by ultracentrifugation and other separation processes. Such separation processes are acceptable to produce low quantities of high value-added products, but are prohibitive for commodity-type surfactants. Furthermore, the low throughput of batch processes and the need for personnel to operate the process also increase the production costs of the biosurfactant. 

Bacteria Heterotroph (methylotroph) Hydrocarbon derivatives (methanol) As carbon source NHs, NH4+... 

One of the commercial methods for production of lysine consists of a two-stage process using two species of bacteria. The carbon sources for production of amino acids are corn, potato starch, molasses, and whey. If starch is used, it must be hydrolysed to glucose to achieve higher yield. Escherichia coli is grown in a medium consisting of glycerol, corn-steep liquor and di-ammonium phosphate under aerobic conditions, with temperature and pH controlled. 

Chitooligomers set free by hydrolases become carbon sources for the growth of intestinal bacteria. Lactobacillus lactis utilizes the oligomers (GlcNAc)i-6, the monomer and dimer being bifidogenic substances [261 -263]. 

Besides nitrogen fixation, the only other major source of reduced nitrogen is the decomposition of soil or aquatic organic matter. This process is called ammonification. Heterotrophic bacteria are principally responsible for this. These organisms utilize organic compounds from dead plant or animal matter as a carbon source, and leave behind NH3 and NHJ, which can then be recycled by the biosphere. In some instances heterotrophic bacteria may incorporate a complete organic molecule into their own biomass. The majority of the NH3 produced in this way stays within the biosphere however, a small portion of it will be volatilized. In addition to this source, the breakdown of animal excreta also contributes to atmospheric... 

Aerobic fermentation Water-l-organic carbon source Air Bacteria... 

PHAs are produced by the bacteria to store carbon and energy reserves (Keshavarz, Roy, 2010). Previous works stated that an intracellular accumulation of PHAs improves the survival of general bacteria under environmental stress conditions (Kadouri et al., 2005 Zhao et al., 2007). Various microorganisms are produced in different properties of biopolymer depending on the types of microorganisms and carbon sources used. More than 150 different monomers can be combined within this family to give materials with extremely different properties (Chen Wu, 2005). 

Table 2. Production of PHAs by various bacteria and carbon sources (Yamane, 1996)...

The majority of PH As biosynthesis is performed by various microorganisms, especially bacteria. They can produce PHAs from a number of substrates and accumulate in their cells as carbon source and energy reserve under imbalanced growth conditions such as nutrient limitation. Fig.7 shows PHA accumulated in their cells that are characterized by transmission electron microscopic (TEM) technique. 

In some cases pectinolytic enzymes have been associated with virulence and it is generally accepted that pectinolysis by these bacteria facilitates their entry and spread in plant tissue. In Rhizohium, these enzymes may play a role in the root infection process that precedes nodule formation (Hubbell et al 1978). A. irakense has never been reported to be pathogenic on plants. It can therefore be speculated that moderate and strictly regulated pectinolysis of A. irakense facilitates entry in the outer cortex of plants roots, since A. irakense has been isolated from surface-sterilized roots. It is likely that breakdown of plant polysaccharides by root colonizing bacteria can provide them with extra carbon source. 

Bacteria have been isolated using reduced anthraquinone-2,6-disulfonate (HjAQDS) as electron donor and nitrate as electron acceptor (Coates et al. 2002). The organisms belonged to the a-, p-, y-, and 5-subdivision of the Proteobacteria, and were able to couple the oxidation of H AQDS to the reduction of nitrate with acetate as the carbon source. In addition, a number of C2 and C3 substrates could be used including propionate, butyrate, fumarate, lactate, citrate, and pyruvate. 

Growth experiments were conducted using bacteria from oil installations with several chemicals normally used in injection water treatment. The studies revealed that some chemicals could be utilized as nitrogen sources, as phosphorus sources, and as carbon sources for the bacteria [1696]. Therefore it is concluded that the growth potential of water treatment additives may be... 

Studies conducted by Pickard et al. (1975) documented that bacteria can use triaryl phosphate-containing hydraulic or lubricating fluids as a carbon source. An innoculum of a mixed bacterial population was... 

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