Microbial strain

Microbial strains must be maintained in such a way that they do not lose their desirable characteristics. Some strains are maintained by regular subculturing, whereas others are lyophilised (freeze-dried), or frozen under nitrogen, or held at -80°C in a freezer. To ensure that a standard inoculum can be obtained on demand, great care is taken to ensure that foe stored cultures are pure and foe viability is known. 

Tim Steinbuchel (1990) studied the mechanisms of Alcaligenes spp. and Rhodospirillum rubrum for PHB synthesis by using butyric acid. Later, Steinbuchel (1991) confirmed the results for the potential of PHAs production and the compositions of PHAs. Under various microbial strains used, different contents of PHAs were obtained. 

Table 3. Variations of PHAs contents in various microbial strains...

To ensure microbial strains are viable and pure a suite of morphological, biochemical, and cytochemical tests are used to confirm characteristics specific to their taxons. A number of commercially available rapid identification kits are also employed for some common genera. In addition to these taxon specific tests, many of the cultures are tested for their fatty acid methyl ester (FAME) profiles using the commercial MIDI system. The FAME profiles can be compared to the MIDI database for species identification/confirmation purposes. The Biolog system, which yields a metabolic fingerprint of an organism, is another alternative for rapid identification. 

The goal is to achieve a polyphasic taxonomic approach for authentication and quality control of microbial strains. Each morphological, physiological, cytochemical, and molecular method has hmitations. Combining and comparing the results enable us to obtain a more accurate and complete picture of the microorganism s identity. 

Other pattern recognition strategies have been used for bacterial identification and data interpretation from mass spectra. Bright et al. have recently developed a software product called MUSE, capable of rapidly speciating bacteria based on matrix-assisted laser desorption ionization time-of-flight mass spectra.13 MUSE constructs a spectral database of representative microbial samples by using single point vectors to consolidate spectra of similar (not identical) microbial strains. Sample unknowns are then compared to this database and MUSE determines the best matches for identification purposes. In a... 

Improving stability of microbial strains in organic solvents is another challenge for enabling commercialization of desulfurization processes for gasoline and diesel applications. This was a target for a project in Klibanov s group [231], whose approach... 

A process, which considered the bio-oxidation of naphthalene compounds using naphthalenes-oxidizing bacteria, was applied for the treatment of gas oil. The quality of the product not only exhibited a sulfur content closed to specifications but also a high lubricity. Description on the used microbial strain was not provided [432],... 

KMMGU Russia Bacteria Database - Microbial Strain Data Network. 

Use of bioflocs rather than supported film particles will maximize the effectiveness factor for a given particle, but uneven growth of floes can cause severe stratification in the bed. If stratification can be overcome by methods such as the use of a tapered bed to control porosity the removal, breaking up, and recycle of biomass at the bottom of the bed or, ideally, the use of microbial strains or species that will stop growing at a desirable floe size, such as a Zymomonas mobilis strain that stops growing at one millimeter in diameter (Scott, 1983), the use of bioflocs rather than support particles can improve reactor productivity. 

Identification of azo dye degrading bacterial strains for use in bioaugmentation typically involves a stepwise process to isolate potential strains and screen them for their ability to degrade different dyes. A number of strategies have been devised to isolate such bacteria to achieve consistent and reproducible results in biotreatment systems (Fig. 2). Specific methods that have been employed for the isolation of microbial strains capable of degrading azo dyes are summarized in Table 2. 

Table 5 Rate of azo dye decolorization by different microbial strains...

In some fortunate instances, an exact match for the desired biotransformation might be available in the literamre that uses a commercial enzyme or microbial strain that is accessible through culmre collections and provides sufficient activity for use in... 

Masson, F., Eclache, L., Compte, L., Talon, C. and Montel, C. (1996). Screening of microbial strains producing amines and isolated from meat products. 546-547. 

CASRN 50471-44-8 molecular formula C12H9CI2NO3 FW 286.11 Biological Golovleva et al. (1991) studied the aerobic biodegradation of vinclozolin in the laboratory and under field conditions using enrichment cultures. Four of the 36 microbial strains isolated were the most active. These were Bacillus cereus 625/1, Bacillus brevis 625/2, Pseudomonas Huorescens 10/3, and 8/28. Under aerobic conditions. Bacillus cereus 625/1 and Pseudomonas Huorescens 8/28 utilized 87-90% vinclozolin as the sole carbon and energy source. Degradation products identified were 2((((3,5-dichlorophenyl)carbamoyl)oxy)2-methyl)-3-bute-... 

Improvement of microbial strains for the overproduction of natural metabolites has been the hallmark of all commercial fermentation processes. Therefore, the aim of this chapter is to highlight several aspects of process improvement to yield natural products for industry at the laboratory, pilot plant and factory scales. 

Parekh S, Vinci VA, Strobel RJ. (2000) Improvement of microbial strains and fermentation processes. Appl Microbiol Biotechnol 54 287-301. 

A microbial strain may produce more than one siderophore. There are variations in fatty acid chains of a lipophilic part or in the amino acids making up the backbone, as well as released intermediates of the biosynthetic chain. These variations belong all to the same structural pattern. However, there is also the possibility that so-called secondary siderophores are encountered. They constitute a different structural type, usually less complex in their constitution but also less efficient in binding Fe " than the primary ones. Secondary siderophores will be produced when the demand for iron is not so severe or in case there is a genetic defect impeding the production of the primary ones. Examples will be found throughout the review. 

The CERCLA Priority List of Hazardous Substances has been annotated with information on the types of wastes and the possible biotechnological treatment methods, as shown in Table 1. The remarks on biotreatabihty of these hazardous substances are based on data from numerous papers, reviews, and books on this topic [4-8]. Databases are available on the biodegradation of hazardous substances. Eor example, the Biodegradative Strain Database [9] (bsd.cme.msu.edu) can be used to select suitable microbial strains for biodegradation applications, while the... 

To prevent growth and dispersion in the waste treatment system of unwanted or nondetermined microbial strains, which may be pathogenic or opportunistic. 

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