The primary cause is governed by the imbalance to utilize proteinaceous plant exudates and to inhibit colonization of other microbes

The present observation also points to the nonspecific nature of protein mediated growth enhancement in P.putida. At this juncture we are not clear on the overall pathway of protein induced growth enhancement in P.putida; this needs to be investigated in detail. Nevertheless, our observation opens up a new avenue in the area of protein mediated signaling in bacteria. Studies pertaining to microbial Cinoxacin communication remain dominated with small molecules like AHL, AI, volatile fatty acids etc. However, there are many emerging reports that have indicated the role played by complex molecules in communication between microbes and microbes and their hosts. Recently, Beauregard et al. have reported sensing of plant-derived polysaccharide by Bacillus subtilis, which influences its biofilm formation capability. On a similar note, Antoniuk and Evseeva showed that lectin could act as a communication molecule between plant and microbes. Gallio et al. elucidated the role played by a conserved rhomboid protein in communication between bacteria and higher organisms. Plants secrete a variety of proteins in the form of root exudates, which have been shown to significantly influence the microbial community structure in rhizospheric environment. These observations were corroborated by many studies employing meta-proteomic approach, where proteins were shown to be influencing microbial dynamics of a given ecosystem. Our observation supports emerging evidence of proteins playing a crucial role in determining microbial community structure. Specifically, we have shown that proteins influence the growth of P.putida, in spite of not being used as a source of carbon or energy. Ecological significance of exogenous protein mediated growth enhancement in P.putida can be explained in terms of the central role played by iron in competitive root colonization and persistence of P.putida in rhizospheric environment. Consequently, factors influencing iron availability to P.putida will have profound impact on its survival and proliferation. Siderophore being the principle molecule responsible for iron uptake, one can expect positive impact of enhanced siderophore secretion on competitive fitness of P.putida. Proteins, as mentioned earlier, are among the major constituents in root exudates and are invariably present in all microorganisms. Therefore, we hypothesize its role as that of a chemical cue, facilitating the survival P.putida in the highly competitive rhizospheric environment. This presumption becomes more relevant when one considers the fact that P.putida can secrete only a single type of siderophore and has only limited capability to utilize heterologous siderophores. Therefore, exogenous protein mediated enhanced siderophore secretion will provide an opportunity to P.putida to achieve an edge over its competitors to accelerate iron assimilation. Enhanced siderophore secretion will facilitate rapid utilization of aromatic compounds normally present in root exudates. Interestingly, secretion of these aromatic hydrocarbons by plants has been shown to become pronounced under iron starvation Euphorbia factor L3 conditions. Consequently, exogenous protein induced siderophore secretion will have two advantages in terms of better assimilation of iron and substrates, which in turn provides the bacterium with fitness advantages over its competitors. Osteoporosis is a worldwide chronic disease which now affects over 200 million people worldwide characterized by low bone mass, poor bone strength and microarchitectural deterioration of bone.

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