Screening of Indonesian peat soil bacteria producing antimicrobial compounds

Dede Mahdiyah; Helmia Farida; Ignatius Riwanto; Mustofa Mustofa; Hendro Wahjono; Tri Laksana Nugroho; Winarto Reki

doi:10.1016/j.sjbs.2020.05.033

Screening of Indonesian peat soil bacteria producing antimicrobial compounds

Saudi J Biol Sci. 2020 Oct;27(10):2604-2611. doi: 10.1016/j.sjbs.2020.05.033. Epub 2020 May 26.

Authors

Dede Mahdiyah^{1

2}, Helmia Farida³, Ignatius Riwanto⁴, Mustofa Mustofa⁵, Hendro Wahjono³, Tri Laksana Nugroho⁶, Winarto Reki³

Affiliations

¹ Department of Pharmacy, Faculty of Health, Sari Mulia University, Banjarmasin, Indonesia.
² Post Graduate Program, Faculty of Medicine, Diponegoro University, Semarang, Indonesia.
³ Department of Clinical Microbiology, Faculty of Medicine, Diponegoro University, Semarang, Indonesia.
⁴ Department of Surgery, Faculty of Medicine, Diponegoro University, Semarang, Indonesia.
⁵ Department of Pharmacology and Therapy, Faculty of Medicine, Public Health and Nursing, Gadjah Mada University, Yogyakarta, Indonesia.
⁶ Department Pharmacology, Faculty of Medicine, Diponegoro University, Semarang, Indonesia.

Abstract

The development and world-wide spread of multidrug-resistant (MDR) bacteria have a high concern in the medicine, especially the extended-spectrum of beta-lactamase (ESBL) producing Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA). There are currently very limited effective antibiotics to treat infections caused by MDR bacteria. Peat-soil is a unique environment in which bacteria have to compete each other to survive, for instance, by producing antimicrobial substances. This study aimed to isolate bacteria from peat soils from South Kalimantan Indonesia, which capable of inhibiting the growth of Gram-positive and Gram-negative bacteria. Isolates from peat soil were grown and identified phenotypically. The cell-free supernatant was obtained from broth culture by centrifugation and was tested by agar well-diffusion technique against non ESBL-producing E. coli ATCC 25922, ESBL-producing E. coli ATCC 35218, methicillin susceptible Staphylococcus aureus (MSSA) ATCC 29,213 and MRSA ATCC 43300. Putative antimicrobial compounds were separated using SDS-PAGE electrophoresis and purified using electroelution method. Antimicrobial properties of the purified compounds were confirmed by measuring the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). In total 28 isolated colonies were recovered; three (25PS, 26PS, and 27PS) isolates produced proteins with strong antimicrobial activities against both reference strains. The substance of proteins from three isolates exerted strong antimicrobial activity against ESBL-producing E. coli ATCC 35,218 (MIC = 2,80 µg/mL (25PS), 3,76 µg/mL (26PS), and 2,41 µg/mL (27PS), and MRSA ATCC 43,300 (MIC = 4,20 µg/mL (25PS), 5,65 µg/mL (26PS), and 3,62 µg/mL (27PS), and also had the ability bactericidal properties against the reference strains. There were isolates from Indonesian peat which were potentials sources of new antimicrobials.

Keywords: Antimicrobial properties; ESBL-producing E. coli; MRSA; Peat soil bacteria.