دانلود رایگان ترجمه مقاله غربالگری، خصوصیات و شناسایی LAB بالقوه پروبیوتیک با فعالیت فیتاز (نشریه Ijcmas 2017)

تعیین مشخصات و شناسایی LAB احتمالی پروبیوتیکی با فعالیت فیتاز

Screening, Characterization and Identification of Probiotic Potential LAB with Phytase Activity

Abstract

Probiotics have been extensively studied and explored commercially in many different products in the world. Looking to the demand and health prospects extensive screening for Lactic Acid Bacteria (LAB) with probiotic potentials was investigated. Total 57 bacterial isolates were collected from the 32 samples. Out of which, 33 LAB isolates were confirmed on the basis of morphological and preliminary biochemical characterization. On the basis of probiotic traits such as low pH and high bile salt tolerance, 8 LAB isolates with probiotic potentials were selected. These were further evaluated for phytase activity which is very important for availing various minerals and proteins in the gut. Two LAB isolates found to show significant phytase activity. Considering the probiotic potential along with phytase activity these isolates show health prospects and therefore they were characterized for identification. Morphological, biochemical and molecular characterization studies revealed Isolate 21 as strain of Pediococcus acidilactici (KU173544) and Isolate 24 (KU173545) as a strain of Pediococcus lolii.

۱ Introduction

According to world health organization probiotics defined as “live microorganisms which when administered in adequate amounts confer a health benefit on the host”. There is growing evidence for their efficacy in protecting against acute diarrhoeal disease in children, gastroenteritis and antibioticassociated diarrhoea, inflammatory bowel diseases and pouchitis (Reid et al., 2003; Geier et al., 2007; Nomoto K., 2005; Weng and Walker, 2006). There is also evidence to support further investigation of the use of probiotics and prebiotics in the treatment of illnesses affecting sites other than the intestinal tract, e.g. urinary tract infections, vaginal infections, arthritis, atopic eczema, pharyngitis and otitis media (Reid et al., 2003; Geier et al., 2007; Tagg and Dierksen, 2003; Lenoir et al., 2007).The numerous perceived health benefits and the growing awareness about probiotics have caught the attention of the food industry (Saarela et al., 2002; Salminen and Gueimonde, 2004). Food companies are increasingly manufacturing foods with incorporated probiotic bacteria, which fall under the new category of foods so called functional foods. Probiotic dairy products such as yogurts containing L. acidophilus and Bifidobacterium spp. constitute a significant amount among the commercially available probiotic foods (Reid et. al., 2003). The goal of functional foods is to improve the quality of life, enhance health status and increase lifespan while maintain health preventing diseases.

Besides imparting all these beneficial attributes probiotics are also known to produce various enzymes that help in the digestion of monogastric animals, phytases and lipases being the important ones. Phytic acid (myo-inositol hexakis phosphate, phytate) is the major storage form of phosphorus in cereals, oil and legumes (Khattak et al., 2006). Phytase, a specific group of phosphatase, hydrolyses phytic acid to myo-inositol and phosphoric acid. In the context of human and animal nutrition, two aspects of phytate are critically important (Reddy et al. 1982; Wodzinski and Ullah, 1996): (i)monogastric animals have only low levels of phytate-degrading enzymes in their digestive tracts, and since phytic acid itself is not absorbed. (ii) phytic acid is considered to be an anti-nutrient factor as it forms complexes with proteins and a variety of metal ions and therefore decreases the dietary availability of these nutrients. Because of these problems, there is considerable interest in phytate-degrading enzymes. Inorganic phosphate is therefore added to their diet to meet the phosphorus requirement, while undigested phytate phosphorus is excreted in manure and poses a serious phosphorus pollution problem, contributing to the eutrophication of surface water in areas of intensive livestock production (Bajaj and Wani, 2011). The formation of insoluble mineral-phytate complexes at physiological pH values is regarded as the major reason for the poor mineral bioavailability, because these complexes are essentially non absorbable from the human gastrointestinal tract (Greiner and Konietzny, 2006). Minerals are involved in activation of intracellular and extracellular enzymes, in regulation of critical pH levels in body fluids necessary for the control of metabolic reactions and in osmotic balance between the cell and its environment. A deficiency of any one of the essential minerals can result in severe metabolic disorders and compromise the health of the organism. Some minerals deficiencies are common in developing countries, but mineral sub-deficiencies may also occur in developed countries (Lopez et al., 2002).

The objectives of present studies were to isolate and identify phytase producing probiotic potential LABs for its exploitation for better health prospects.