Screening of Bacterial Isolates from Cow Manure with Potential as Antagonist Agents against Alternaria porri (Ellis) Cif.

Sherin Rizkina (Universitas Islam Negeri Sultan Syarif Kasim Riau)
Syukria Ikhsan Zam (Universitas Islam Negeri Sultan Syarif Kasim Riau)
Mokhamad Irfan (Universitas Islam Negeri Sultan Syarif Kasim Riau)
Irwan Taslapratama (Universitas Islam Negeri Sultan Syarif Kasim Riau)
Yusmar Mahmud (Universitas Islam Negeri Sultan Syarif Kasim Riau)
Siti Zulaiha (Universitas Islam Negeri Sulthan Thaha Saifuddin Jambi)
Oksana Oksana (Universitas Islam Negeri Sultan Syarif Kasim Riau)
Nida Wafiqah Nabila M. Solin (Universitas Islam Negeri Sultan Syarif Kasim Riau)

El-Hayah : Jurnal Biologi
Vol 10, No 5 (2026): EL-HAYAH (VOL 10, NO 5 September 2026)

Environmentally friendly control of Alternaria porri (Ellis) Cif. can be carried out using antagonistic agents such as bacteria. Exploration of bacterial sources as antagonistic agents needs to be continuously conducted, one of which is from cattle manure. This study aimed to obtain potential antagonistic bacteria against A. porri. Samples were collected using a purposive sampling technique. Bacterial isolation was performed using the spread plate method from dilutions of 10⁻⁶ to 10⁻⁸. Antagonistic activity was assessed using the dual culture method. This research obtained four isolates—PKa, PKb, PKc, and PKd—with cell counts ranging from 0.12 × 10⁹ to 1.83 × 10⁹ CFU g⁻¹. All isolates belonged to the Gram-positive group. Isolate PKa exhibited no catalase activity, whereas isolates PKb, PKc, and PKd showed catalase activity. PKa was identified as Clostridium, while PKb, PKc, and PKd were identified as Bacillus. All isolates demonstrated potential as antagonistic agents, with antagonistic activity ranging from 82% to 90%.