Egypt. J. Exp. Biol. (Bot.), 13(1): 81 – 87 (2017) © The Egyptian Society of Experimental Biology DOI: 10.5455/egyjebb.20170313075413 ISSN: 1687-7497 On Line ISSN: 2090 - 0503 http://my.ejmanger.com/ejeb/ RESEARCH ARTICLE Hend Abdulhmeed Hamedo Nashwa Ibrahim Hagagy Naglaa Fathi El Shafi Mohamed Helmy Abd Elaziz Screening of hydrolytic extremozymes in haloalkaliphilic Archaea by culture and molecular-based methods ABSTRACT: Exploring of extremophilic Archaea and their enzymes had great significance to biocatalysis. Enzymes produced by Archaea allow improvement in multiple sectors of industry. They can help reduce the quantity of waste energy and material consumption, thus making the technology more environmentally – friendly. This study aimed to screen hydrolytic extremozymes in different Soda Lakes of Wadi Al-Natrun, Egypt, by enzymatic agar-plate assays and molecular-based methods. Five hundred and thirty-five haloalkaliphilic archaeal strains isolated from different Soda Lakes were screened for production of protease, amylase, pectinase, chitinase, cellulase, lipase and esterase at pH 10 and 25% NaCl (w/v). Furthermore, metagenomic DNA was extracted from water sample of Ga'ar Lake and constructed library were sequenced to identify the genes encoding target enzymes by using illumina Hiseq2000 system. By enzymatic agar- plate assay, all tested strains showed potential production of extracellular enzymes, a total of 39.4% of screened strains produced protease, 27.1% showed amylase activity, 25.9% for lipase and 7.4% displayed cellulase activity, but none of tested strains produced chitinase or pectinase. While, by shotgun metagenomic technique, all genes encoding metabolically active hydrolytic enzymes studied were detected in water sample of Ga'ar Soda Lake. Metagenome-derived DNA libraries have focused on many classes of enzymes, among these hydrolytic enzymes were prominent. The results of both methods indicated that these soda lakes are rich with commercially valuable enzymes. KEY WORDS: Extremozymes, Extracellular activity, Metagenome, Soda Lakes, Wadi Al- Natrun, Egypt. CORRESPONDENCE: Hend Abdulhmeed Hamedo Botany Department, Faculty of Science, Al- Arish University, AL-Arish, Egypt E-mail: hend_hamedo@hotmail.com Nashwa Ibrahim Hagagy** Naglaa Fathi El Shafi* Mohamed Helmy Abd Elaziz** * Botany Department, Faculty of Science, Al- Arish University, AL-Arish, Egypt ** Botany Department, Faculty of Science, Suez-Canal University, Ismailia, Egypt ARTICLE CODE: 08.02.17 INTRODUCTION: Extremophiles, able to live in unusual habitats, can potentially serve in a verity of industrial applications (Horikoshi, 2008). The groups of Halobacteriaceae that can grow under alkaline conditions in the presence of salt are referred as haloalkaliphiles. The dual extremity of halolkaliphiles make them interesting models for fundamental research and exploration of biotechnological potential (Dodia et al ., 2008; Joshi et al ., 2008; Bominadhan et al ., 2009; Purohit and Singh, 2011). Haloalkaliphilic archaea have largely been studied from the concentrated hyper saline environments; Soda Lake, Solar Saltern, Salt brines, Carbonate springs and Dead Sea. Soda Lakes represent stable and extremely productive aquatic ecosystems. Most of the alkaline Soda Lakes in Africa, India, China and elsewhere with pH values of 11 and higher and salt concentrations exceeding 300 g/l are teeming with life (Oren, 2002). The enzymes from extremophilic organisms, particularly halophilic and