Introduction Cellulose, hemicelluloses, and lignin are the main consistent of the lignocellulosic biomass. Cellulose bonds strongly with hemicellulose and lignin [1]. Cellulose (C 6 H 10 O 5 ) appears as a closely packed dense structure when crystallized. It comprises thousands of glucose subunits linked by a linear β-1,4-glycosidic linkage. The effcient usage of the cellulosic wastes products for the economical production of cellulose through the development of sustainable systems has recently gained interest [2]. Worldwide attention has turned to utilize different cellulolytic microorganisms for the bioconversion of cellulose into valuable products, such as alcohol and sugar. The procedure is carried out under high temperature and pressure. Cellulases, a category of glycosyl hydrolases, involving Pol. J. Environ. Stud. Vol. 30, No. 3 (2021), 2459-2466 Original Research Optimization of Cellulase Production from Bacillus albus (MN755587) and Its Involvement in Bioethanol Production Emad A. Abada 1,4 *, Reham M. Elbaz 2,4 , Hana Sonbol 3 , Shereen M. Korany 3,4 1 Biology Depatrment, Faculty of Science, Jazan University, Jazan, Saudi Arabia 2 Department of Biology, College of Science, University of Bisha, P.O. Box 551, Bisha 61922, Saudia Arabia 3 Biology Department, Faculty of Science, Princess Nourah Bint Abdulrahman University, 84428 Riyadh, Saudi Arabia 4 Botany and Microbiology Dep., Faculty of Science, Helwan University, Cairo, Egypt Received: 16 July 2020 Accepted: 1 November 2020 Abstract Worldwide attention has turned to utilize different cellulolytic microorganisms for the bioconversion of cellulose into valuable products, such as bioethanol. The aim of this work is to isolate cellulase- producing bacteria, optimization the growth conditions, production of bioethanol and possible use in pharmaceutical industry. Twenty cellulase-producing bacterial isolates (Coded alphabetically from A–T) were isolated from Jazan soil. The ‘E’ isolate showed maximum cellulase production. The isolate was characterized by 16S rRNA analysis. The gene sequence of E isolate indicated that the DNA sequence was 99.6% homologous with 16S rRNA gene sequences of Bacillus albus. The highest cellulase activity of B. albus was achieved when the bacterial growth media was at pH 6, supplemented with glucose, maltose, Carboxy methyl cellulose (CMC), and lactose (1%, w/v), and inoculated with 3% (v/v) and incubated at 35ºC for 96 h. The results indicate the liberation of 2.0 g/l reducing sugar via the DNS method. The total reducing sugar produced was 12.4 g/l of ethanol after 72 h, when Saccharomyces cerevisiae was used as a fermentation agent. Large scale production of bioethanol is recommended for possible use in industry. Keywords: carboxy methyl cellulose, cellulase, Bacillus albus, bioethanol *e-mail: emadm_abada@yahoo.co.uk DOI: 10.15244/pjoes/129697 ONLINE PUBLICATION DATE: 2021-04-01