Chapter 18. Advancement on bacterial enzyme technology for industries: research and application of novel biocatalysts

HÉCTOR A. CRISTÓBAL; CARLOS M. ÁBATE; ALICIA G. CID; VERÓNICA B. RAJAL

Applications of Microbial Genes in Enzyme Technology

Nova Science Publishers

Lugar: New York; Año: 2013; p. 353 - 374

A wide range of novel enzymes for biocatalysts adapted to industrial processes has been obtained from extremophile microorganisms. Marine environments possess an enormous microbial biodiversity and potential sources of many biological compounds for the development of exploitable biotechnology. The demand of biocatalysts adapted to extreme conditions (low or high temperatures, acidic or basic pH and high salt concentration) increases in the industry. The enzyme industry worldwide is valued at US $5.1 billion and it is predicted to show an annual increase in demand of 63%. Advances in biotechnology, coupled with growing scientific developments, promise technological innovations in a wide range of biotechnological applications for industries, which will be beyond estimation. Many fields of biotechnological studies need to understand the natural mechanisms in biological systems to use this information towards an integrated analysis of genes or proteins expression. In nature, as well as during industrial processes, bacteria are exposed to changes in environmental physico-chemical parameters, which may impair their growth or survival. In this chapter, we focus the studies on Shewanella sp. G5, a psychrotolerant bacterium, which exhibits three beta-glucosidases. Two of these isozymes were classified under the glycosyl hydrolase families 1 and 3, encoded by bgl-A (EF141823) and bgl (DQ136044) genes. These beta-glucosidases may be of interest for winemaking and citrus juice technology processing at low temperatures. The identification of proteins or genes and its expression patterns under different growth conditions (carbon source, culture media and temperature) were studied by proteome analyses. Two-dimensional gel electrophoresis was performed and whole protein pattern of Shewanella sp. G5 revealed that 59 and 55 proteins spots were induced by cellobiose and glucose, respectively. Proteomic analyses showed that Shewanella sp. G5 re-organizes its metabolism in response to all the variables assayed, indicating expression of housekeeping and specific proteins for a particular condition. Determinate proteins spots expression showed increases, which allowed elucidating the quantitative changes relevant in the levels of gene expression. The identification of these proteins spots suggested that different master regulation schemes are involved in response to glucose and cellobiose carbon sources, and were compared with genome sequence data available for Shewanella oneidensis. These results allowed us to establish the optimum growth conditions for production of beta-glucosidases, taking into account the greatest induction.