Isolation and Identification of Lactic Acid Bacteria from Different Sources and Testingtheir Ability to Produce Cellulases Enzyme abstract
The current study aims to enhance work in the field of isolating microorganisms that produce enzymes with practicaluses, sustainability and food industries, by isolating and identifying lactic acid bacteria strains from different sources, some of whichcontain cellulose, which microorganisms depend on, primarily for their nutrition and reproduction, and which is present in theenvironment in which they are found, and the possibility of producing the enzyme Cellulase, which is considered one of the importantenzymes in the analysis of polysaccharides (cellulose) and the production of monosaccharides and simple sugars. This study includedthe isolation and identification of Lactobacillus bacteria from different sources, purification, screening, identification anddetermination of their efficiency in producing cellulase enzymes. The results showed that fifteen isolates were obtained from varioussources including soil, fruits, vegetables, pickles, dairy products and live fish entrails. Agar MRS medium with 0.5% (w/v) CaCl2granules was used to isolate lactic acid bacteria, which were identified by phenotypic, biochemical and Gram staining tests. Apreliminary screening was performed by estimating the enzyme activity on the solid medium by measuring the diameter of thetransparent halo formed around the colonies in the medium. The results were enhanced by measuring the activity of the enzymeproduced on the liquid medium by measuring the light absorption using a spectrophotometer. The results obtained showed that thebest isolates in enzyme production are the isolates that produced the highest enzyme efficiency on the solid medium, which is theone isolated from the guts of live fish (fish 3), which formed a transparent halo with a diameter of 3 cm on the solid medium and thehighest efficiency in the liquid medium, which obtained the highest absorption in the spectrophotometer, highest enzymatic activity,reaching 4.546 and Specific activity 10.331. After selecting the best isolate from among the isolates, the optimum conditions forenzyme production were studied in different situations, including [temperature, pH, vibrating incubator speed, inoculum quantity,different carbon and nitrogen sources and the period required for fermentation], and the following results were obtained: Theoptimum temperature for production is 35 °C with an enzymatic activity reached (3.425) and Specific activity (4.502), the pH valuewas 6 with the enzymatic activity reached (3.437) and Specific activity (4.399), the enzymatic activity was (3.419), and specificactivity was (4.804), a fermentation time of 72 hours with an efficiency of (3.065) and Specific activity (4.305),the best carbonsource cellulose with an efficiency of (5.44), and the best Nitrogen source wheat bran with an efficiency of (3.634) and a inoculumcontent of 5% with an efficiency of (3.399).
