2 Physicochemical Approaches to Studying Plant Growth Promoting Rhizobacteria

Within the last few decades, the application of instrumental techniques in scientific research related to life sciences and biotechnology has been rapidly expanding. This trend largely concerns biochemistry and biophysics, thus reflecting the interpenetration and interrelationship between different fields of natural sciences in studying biological objects [1]. Albeit to a lesser degree, the use of physicochemical techniques is increasingly being put into practice in microbiology. The possibility of obtaining reliable, selective and sometimes unique information about sophisticated biological systems under study at different levels of their organization (e.g. organism, tissue, cell, cellular supramolecular structures, biomacromolecules, low-molecular-weight metabolic products, etc.) and functioning is an attractive feature of modern instrumental techniques. In addition, some techniques are nondestructive and/or provide information on intact biological matter with a minimum of sample preparation, which most closely reflects its natural state. Moreover, the bioanalytical information obtained by a combination of independent instrumental techniques may be of significant advantage, especially when comparing data on overall cellular metabolic changes (e.g. as cellular responses to some environmental factors) with analyses for microelements (e.g. trace metal uptake) and/or their chemical forms (speciation analysis). The scientific literature of recent decades provides evidence that the field of plant growth promoting rhizobacteria (PGPR) and their interactions with host plants is highly promising for possible wide-scale applications in returning to environmentally friendly and sustainable agriculture. However, there are still a great number of problems related to the basic mechanisms of the underlying biological and chemical processes that occur both in the rhizosphere and in vivo (in plants and PGPR), which require systematic research at the molecular level using modern techniques. In this chapter, some recent examples are discussed which illustrate the use of various physicochemical and spectroscopic approaches, involving a range of j19