Abstract:This study aimed to isolate pullulanase-producing strains from Qingdao marine mud. Through morphological，physiological，biochemical，and 16S rRNA analyses，the strain's enzymatic properties were investigated. The enzyme was then used to treat starches from 12 different sources（buckwheat，corn，sweet potato，wheat，barley，glutinous rice，water-milled glutinous rice，lily，broad bean，kudzu root，mung bean，and yam）. A strain producing typeⅡpullulanase，Bacillus sp. A1，was obtained. The optimal reaction temperature and pH for the enzyme were 40 ℃ and 5，respectively. After incubation at 45 ℃ and 55 ℃ for 2 h，the relative enzyme activity remained above 70%. The enzyme exhibited high stability in buffers with pH values ranging from 5 to 7，indicating good thermal and pH stability. Treatment with the enzyme resulted in the formation of uniform and deeply penetrating pores in buckwheat，corn，and sweet potato starches. Compared with those of native starches，the solubility and swelling power of the porous starches increased by approximately 2.11% and 2.25%，respectively. After 24 h of enzymatic hydrolysis，the water and oil absorption capacities of the porous starches increased by approximately 44.80% and 30.11%，respectively，compared with those of native starches.In summary，this enzyme shows potential for application in the preparation of porous starches from buckwheat，corn，and sweet potato.