{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/111023"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/111023","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Sporulation and toxin formation in Bacillus sphaericus 1593","abstract":"The effects of temperature, dissolved oxygen, and pH on the growth, sporulation, and mosquito larval toxin formation by B. sphaericus 1593, were investigated in shaken flasks and a fermenter. The bacteria grew well at temperatures of 25 to 40°C, however, toxin-formation and sporulation were poor at temperatures above 30°C. Cell lysis became evident after about 30 hours into the fermentation, particularly in case of high temperatures. Mature spores, as well as most of the toxin, were formed by 24 to 30 hours of growth. Controlling the pH at 7.0, gives about ten-fold more toxicity as compared to experiments with no pH control. Simultaneous assay of ammonia concentration indicated a close parallel between the ammonia and pH profiles. Assays of carbohydrate, protein, and phosphorous indicated that none of these nutrients were limiting at any time, thus none of them could have been the limiting nutrient that triggers sporulation. It was found that dissolved oxygen concentrations dropped nearly to zero in case of fermentation with sparged air, but were significant in the case of fermentation with sparged oxygen even at their minimum. The toxicity was approximately equal in both the cases, however sporulation was poor in the case of experiments sparged with pure oxygen. Measurements of oxygen uptake rates confirmed that the cells respire more when the cells are in the vegetative phase of growth.","abstract_html":"The effects of temperature, dissolved oxygen, and pH on the growth, sporulation, and mosquito larval toxin formation by B. sphaericus 1593, were investigated in shaken flasks and a fermenter. The bacteria grew well at temperatures of 25 to 40°C, however, toxin-formation and sporulation were poor at temperatures above 30°C. Cell lysis became evident after about 30 hours into the fermentation, particularly in case of high temperatures. Mature spores, as well as most of the toxin, were formed by 24 to 30 hours of growth. Controlling the pH at 7.0, gives about ten-fold more toxicity as compared to experiments with no pH control. Simultaneous assay of ammonia concentration indicated a close parallel between the ammonia and pH profiles. Assays of carbohydrate, protein, and phosphorous indicated that none of these nutrients were limiting at any time, thus none of them could have been the limiting nutrient that triggers sporulation. It was found that dissolved oxygen concentrations dropped nearly to zero in case of fermentation with sparged air, but were significant in the case of fermentation with sparged oxygen even at their minimum. The toxicity was approximately equal in both the cases, however sporulation was poor in the case of experiments sparged with pure oxygen. Measurements of oxygen uptake rates confirmed that the cells respire more when the cells are in the vegetative phase of growth.","abstract_has_math":false,"creators":["Madhekar, Nandu M."],"institution":"Virginia Polytechnic Institute and State University","degree_name":"M.S.","degree_level":"masters","degree_discipline":"Chemical Engineering","degree_department":"Chemical Engineering","school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1983,"date_issued":"1983","date_published":"1983","updated_at":"2026-07-22T22:19:42Z","subjects":[],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/10919/111023","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.department","label":"Department","values":["Chemical Engineering"]},{"key":"dc:creator","label":"Author","values":["Madhekar, Nandu M."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2022-06-29T19:26:46Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2022-06-29T19:26:46Z"]},{"key":"dc:date.issued","label":"Date","values":["1983"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Polytechnic Institute and State University"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/111023"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["The effects of temperature, dissolved oxygen, and pH on the growth, sporulation, and mosquito larval toxin formation by B. sphaericus 1593, were investigated in shaken flasks and a fermenter. The bacteria grew well at temperatures of 25 to 40°C, however, toxin-formation and sporulation were poor at temperatures above 30°C. Cell lysis became evident after about 30 hours into the fermentation, particularly in case of high temperatures. Mature spores, as well as most of the toxin, were formed by 24 to 30 hours of growth. Controlling the pH at 7.0, gives about ten-fold more toxicity as compared to experiments with no pH control. Simultaneous assay of ammonia concentration indicated a close parallel between the ammonia and pH profiles. Assays of carbohydrate, protein, and phosphorous indicated that none of these nutrients were limiting at any time, thus none of them could have been the limiting nutrient that triggers sporulation. It was found that dissolved oxygen concentrations dropped nearly to zero in case of fermentation with sparged air, but were significant in the case of fermentation with sparged oxygen even at their minimum. The toxicity was approximately equal in both the cases, however sporulation was poor in the case of experiments sparged with pure oxygen. Measurements of oxygen uptake rates confirmed that the cells respire more when the cells are in the vegetative phase of growth."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["M.S."]},{"key":"dc:format.mimetype","label":"Dc Format Mimetype","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Sporulation and toxin formation in Bacillus sphaericus 1593"]}]}],"canonical_facts":{"dc:contributor.department":["Chemical Engineering"],"dc:creator":["Madhekar, Nandu M."],"dc:date.accessioned":["2022-06-29T19:26:46Z"],"dc:date.available":["2022-06-29T19:26:46Z"],"dc:date.issued":["1983"],"dc:description.abstract":["The effects of temperature, dissolved oxygen, and pH on the growth, sporulation, and mosquito larval toxin formation by B. sphaericus 1593, were investigated in shaken flasks and a fermenter. The bacteria grew well at temperatures of 25 to 40°C, however, toxin-formation and sporulation were poor at temperatures above 30°C. Cell lysis became evident after about 30 hours into the fermentation, particularly in case of high temperatures. Mature spores, as well as most of the toxin, were formed by 24 to 30 hours of growth. Controlling the pH at 7.0, gives about ten-fold more toxicity as compared to experiments with no pH control. Simultaneous assay of ammonia concentration indicated a close parallel between the ammonia and pH profiles. Assays of carbohydrate, protein, and phosphorous indicated that none of these nutrients were limiting at any time, thus none of them could have been the limiting nutrient that triggers sporulation. It was found that dissolved oxygen concentrations dropped nearly to zero in case of fermentation with sparged air, but were significant in the case of fermentation with sparged oxygen even at their minimum. The toxicity was approximately equal in both the cases, however sporulation was poor in the case of experiments sparged with pure oxygen. Measurements of oxygen uptake rates confirmed that the cells respire more when the cells are in the vegetative phase of growth."],"dc:description.degree":["M.S."],"dc:format.mimetype":["application/pdf"],"dc:identifier.uri":["http://hdl.handle.net/10919/111023"],"dc:language.iso":["en"],"dc:publisher":["Virginia Polytechnic Institute and State University"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:title":["Sporulation and toxin formation in Bacillus sphaericus 1593"],"dc:type":["Thesis"],"dc:type.dcmitype":["Text"],"thesis:degree_discipline":["Chemical Engineering"],"thesis:degree_level":["masters"],"thesis:degree_name":["M.S."],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-22T22:19:42Z"}