2025, Vol. 6, Issue 1, Part B
Bioprospecting of antibiotics-producing Bacillus species isolated from soil samples obtained from food vendor sites in Port Harcourt, Nigeria
Author(s): Gloria Chile Amadi-Wali, Vivian Nkemkanma Agi and Easter Godwin Nwokah
Abstract: Microbial resistance against numerous existing antimicrobial agents is one of the most urgent challenges the world is currently facing. There has been increased quest for new or alternative remedies. The aim of this study was to evaluate antimicrobial potentials of some metabolites from Bacillus species recovered from soil samples obtained from food vendor site within Port Harcourt, Nigeria. These Bacillus species were isolated and subjected to different changes in environmental conditions such as stress time, temperature and pH for the production of secretory molecules. Twenty-four (24) soil samples were collected at random from food vendor site in Port Harcourt and 1g of the soil sample was measured and dissolved in 9 ml of sterile distilled water and shaken vigorously for 2 minutes and a ten-fold serial dilution of the sample was prepared using normal saline. A 0.1 ml aliquot of the sample was inoculated onto already prepared media using pour plate method and incubated at 37 °C for 24 hours. Stockculture of Bacillus species for the exposure study was made by inoculating each Bacillus species into 1000µl of peptone water in test tubes and the pH of the medium was adjusted to 4.0 and 8.0 with HCl and were subjected to temperatures of 4 °C, 30 °C, 40 °C, and 45 °C and then incubated for 72 hours. After 48 hours of incubation, 2 mls of the stockculture were transferred into 2 mls sterile test tube and spun using a centrifuge at 3000rp\m for 10 minutes to obtain the supernatant. This process was repeated after 72 hours of incubation. Spread plate technique was used to plate already purified standard microorganisms such as Escherichia coli, Klebsiella species, Pseudomonas species and Staphylococcus aureus on Mueller Hinton agar and supernatant obtained from the exposure study were dropped in the wells made on the agar plate which contain the known microorganisms and incubated for 24 hours at 37 °C and the diameter of inhibition zones was measured in millimeter. There was no significant difference in the types of isolate obtained from each soil depth sampled and Staphylococcus species and Bacillus species were isolated from all the soil depth. The Extract obtained from the exposure study contained 2-Norbornyl acetate, exo-Norborneol, methyl ether, 3-Phenoxy Propionic acid, Carbamic acid and phenyl ester according to the result obtained from Chromatography/Mass spectrometry (GC-MS) analysis conducted. With stress time increased from 48 hours to 78 hours, there was no significant difference in the mean of zone of inhibition. The result of temperature from 4 °C, 30 °C, 40 °C and 45 °C, pH from acidity (4) to alkalinity (8) and time from 48 hours to 72 hours showed that temperature, pH and time are crucial for the synthesis of bioactive secretory molecules. These secretory molecules showed varying degrees of antibiotic activity by their different zone of inhibitions. It was concluded that secretory molecules produced by Bacilli isolated from the soil were chemically similar to the molecules found in phytochemicals such as flavonoids, alkaloids, terpenoids, and phenolic compounds. Further studies on gene expression at different stress, time, pH and temperature may be required.
DOI: 10.22271/micro.2025.v6.i1b.209
Pages: 143-148 | Views: 83 | Downloads: 53
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How to cite this article:
Gloria Chile Amadi-Wali, Vivian Nkemkanma Agi, Easter Godwin Nwokah. Bioprospecting of antibiotics-producing Bacillus species isolated from soil samples obtained from food vendor sites in Port Harcourt, Nigeria. J Adv Microbiol Res 2025;6(1):143-148. DOI: 10.22271/micro.2025.v6.i1b.209
