دانلود رایگان ترجمه مقاله تقویت تولید فیتاز از یک پروبیوتیک باسیلوس سوبتیلیس P6 جدید (نشریه Ijcmas 2017)

تقویت تولید فیتاز از یک سوش جدید پروبیوتیک Bacillus Subtilis P6

Enhancement of Phytase Production from a New Probiotic Strain Bacillus subtilis P6

Abstract

An integrated classical and statistical optimization approach involving the combination of Placket–Burman design (PBD) and Central Composite Design (CCD) was employed for increasing phytase yield. PBD was used to evaluate the effect of 9 variables related to phytase production from probiotic strain B. subtilis, and three statistically significant variables, namely, glucose, beef extract and potassium phosphate were selected for further optimization studies. The levels of five variables for maximum phytase production were determined by a CCD. The optimum values for the factors were determined via response surface methodology (RSM) as: 6.59 gl-1 of glucose, 6 gl-1 of beef extract and 2.75 gl-1 of potassium phosphate respectively. Phytase production improved from 2.74 EUml-1 to 46.76 EUml-1 indicating 17-fold increase in activity after optimization.

۱ Introduction

The growing awareness of the diet and health has prompted an increasing demand of food products that can support health apart from providing basic nutrition (Haros et al., 2009). Since last six decades, a lot of antibiotics have been incorporated in animal feed to improve their growth, efficiency and to protect them from pathogenic microorganisms.

But, antibiotic resistance has become a major public health concern today (Sharma et al., 2014). The gastrointestinal microflora plays beneficial role in the health and nutrition of animals, and probiotics, live microorganisms help in the maintenance of gut microflora. Probiotics have been strongly recommended as alternatives to antibiotics for food animals (Reid and Friendship, 2002). Recently, a great deal of attention has been devoted to the genuine value of bacterial species as multifunctional probiotics, which secrete various extracellular enzymes for enhancing feed digestibility as well as many antimicrobial compounds for improving animal performance (Lee et al., 2012); among them phytase holds the key position. Phytate is a natural phosphate reservoir in plant based animal feed and acts as an anti-nutritional factor in gut of animals and humans by restricting absorption of proteins, carbohydrates, amino acids and metals viz. Zn2+, Fe3+, Ca2+ and Mg2+ . However, in order to meet the phosphorus requirement, diet of monogastric animals are supplemented with inorganic phosphorus which causes the excretion of large amount of phosphorus in the excreta resulting in environmental pollution and several human health problems (Jorquera et al., 2011). Phytase (myo-inositol hexakisphosphate phosphohydrolase, E.C. 3.1.3.8 or E.C. 3.1.3.26) are group of enzymes that hydrolyze phytate to inositol phosphate, myo-inositol and inorganic phosphate. Today, phytase extracted from fungi (Nautophos® , Allzyme® SSF, Finase® P/L) is commercialized as feed supplement; on the other hand several bacterial species have been used as probiotics.

But till date, phytase producing probiotic strains have not been commercialized. However, a probiotic strain with phytase activity can perform double function and enhance productivity of animals manifolds. Simultaneously, they can also reduce the serious environmental problems caused by undigested phytate, which is main byproduct of human and animal excreta. Hence, from last few years, this area has become a major public health concern and is drawing the interest of health and research professionals all around the world.

One of the major cornerstones in biotechnology today is the optimization of the cultivation conditions for enhancing the productivity. Screening and evaluation of nutritional requirements of microorganisms is an important step in any bioprocess development.

Optimization studies involving one factor-ata-time approach is tedious, tends to overlook the interaction among the factors and might lead to misinterpretation of results. In contrast, statistical strategies are preferred and more advantageous and mitigate the error in determining the effects of parameters in an economical manner (Sharma and Satyanarayana, 2006). The empirical technique is a traditional optimization method employing one-factor-at-a-time strategies which is simple, easy and explains the individual effect of different components. Unfortunately, it is tedious and fails to explain the interactions among the factors (Awad et al., 2011). Statistical optimization is a proven tool for overcoming the limitations of the “one-factor at a time‟ method. It is more efficient technique since it can provide statistical data with a relatively small number of experiments.

In our previous endeavor, we isolated phytase producing potential probiotic strain Bacillus subtilis P6 from exotic environment (Sharma and Trivedi, 2015). Considering the high potential of phytase for use as feed supplement and its future prospective in animal feed and human nutrition, the present appraisal therefore aims at achieving the multifold improvement in the phytase production through sequential classical and statistical optimization strategy from probiotic strain Bacillus subtilis P6 so as to verify whether it can become a new kind of feed additive for food and animal feeding in the future.