https://bestjournal.untad.ac.id/index.php/ejurnalfmipa <p><a title="Link Sinta" href="https://sinta.kemdikbud.go.id/journals/profile/288" target="_blank" rel="noopener"><strong>Natural Sciences: Jurnal of Science and Technology</strong> [eISSN : 2541-1969 | pISSN : 2338-0950]</a> is an open access journal from Tadulako University, Indonesia. Natural Sciences: Journal of Science and Technology (hence JST) is an international journal providing an authoritative source of scientific information for researchers in academia, research institutions and government agencies, and industries. We publish original research papers, review articles and case studies on the scientific works in the field of life science in tropical area including biodiversity and environment, ecology, biotechnology, bioinformatics, molecular biology, biochemistry, ethnobiology, herbal medicine, zoology and botany as well as related topics. JST does not accept papers related to the topic of material science, education, economy, social and humanities and other issues outside the topic of life science. All papers are peer-reviewed by at least two referees. Other topics are welcome if it discusses biodiversity or biotechnology. Natural Sciences: Journal of Science and Technology is published and imprinted by Faculty of Science, Tadulako University (UNTAD) and managed to be issued twice in every volume. For further information, please visit https://bestjournal.untad.ac.id/index.php/ejurnalfmipa.</p> <p><strong>Natural Sciences: Journal of Science and Technology</strong> <span class="fontstyle0">officially published three times a year. But, starting on January 1, 2021 Journal of Science and Technology will be published twice a year.</span></p> Faculty of Science, Tadulako University, Sulawesi, Indonesia. en-US Natural Science: Journal of Science and Technology 2338-0950 Authors who publish with this journal agree to the following terms:<br /> <br /><ol type="a"><ol type="a"><li>Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a <a href="http://creativecommons.org/licenses/by/3.0/" target="_new">Creative Commons Attribution License</a> that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.</li></ol></ol><br /><ol type="a"><ol type="a"><li>Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.</li></ol></ol><br /><ol type="a"><li>Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) prior to and during the submission process, as it can lead to productive exchanges, as well as earlier and greater citation of published work (See <a href="http://opcit.eprints.org/oacitation-biblio.html" target="_new">The Effect of Open Access</a>).</li></ol> https://bestjournal.untad.ac.id/index.php/ejurnalfmipa/article/view/17057 <p>A stability study of previously isolated and selected crude amylase PL-16 has been performed. The purpose of this study was to determine the effect of pH and temperature alterations on the stability of crude amylase enzymes PL-16 produced by thermophilic bacteria found in Pulu hot springs in Central Sulawesi. Stability characterization was carried out by storing and incubating crude amylase for 24 hours and at elevated heat prior to activity assay at varied pH and temperatures. Enzyme activity following characterization was determined by the DNS method and UV-VIS spectrophotometry at a wavelength of 540 nm, using maltose as the standard. The results showed that at storage for 24 hours with pH varied from 5-12, the crude amylase enzyme activity was able to maintain its 85-95% stability in the pH range of 7-9, then decreased in stability at pH of 10-12. While at 2 hours storage in elevated temperature, it maintained 84-85% stability against heat at 70-80 °C, then decreased at higher temperatures. Our results suggested that crude amylase PL-16 is a promising candidate for industrial enzyme application due to its capability to maintain stability in high temperatures and acidic to neutral pH.</p> Pasjan Satrimafitrah Nov Irmawati Inda Navalia Mahensiska Indasari Copyright (c) 2024 Natural Science: Journal of Science and Technology http://creativecommons.org/licenses/by-nc/4.0 2024-06-28 2024-06-28 13 1 1 5 10.22487/25411969.2024.v13.i1.17057