An investigation for exocellulase and endocellulase activities of thermotolerant Gram-positive bacteria from Al-Baha region, Saudi Arabia

This study was designed to explore some bacterial genera with the ability to decompose cellulosic materials from different places in Al-Baha region. All the collected and prepared compost samples in Nawan, Almakhwah and Bani Zabyan, Al-Baha  were used for bacteria isolation on cellulose powder and CMC substrates as sole sources of carbon. Six isolates were obtained in both types of media. All the twelve isolates were described as thermotolerant as the incubation temperature was 45 °C. Basic morphological and physiological description for all isolates showed a high degree of similarity with bacteria of the genera Bacillus, Amphibacillus, Paenibacillus in case of all the spore forming isolates, and Lactobacillus in case of the non-spore forming isolate A2. The accuracy of the description of the isolates was confirmed by PCR detection of the cellulase genes ß-glucosidase and 6-phospho-ß-glucosidase in bacteria like the isolates under study. This assay was performed in-silico through an online program using primers designed specifically for Bacilli and Lactobacilli. Growth curves for all isolates showed maximum growth activity at 24 to 30 hours from the start of incubation except for isolate B1, which reached the maximum growth at 24 hours. Application of the isolates for plant waste composting under laboratory conditions in consortia was conducted. Finally, a simple experiment for planting fenugreek seeds was conducted to test quality of the compost and to ensure that it is free of any toxic substances for plants. The results showed the quality of the compost produced in both natural and laboratory conditions.