Isolation and identification of subtilosin A-producing Bacillus subtilis from mongo sprouts, silage and soil samples in the Philippines

Issue Date

7-2016

Abstract

Bacillus subtilis was selectively isolated from mongo sprouts, silage and soil samples. Thirty one pure isolates were obtained and were partially characterized using conventional microbiological methods. Based on cultural characteristics, five groups were identified and each of the 31 isolates was placed in one of these groups. One representative isolate was randomly selected from each group and were designated as BSI, GS4, DH4, DH6 and SIL15. These five isolates were found to be 99-100% similar to B. subtilis after 16s rRNA gene sequence analysis. They were also found positive for the sboA gene as revealed by a 722bp PCR product which encodes for the bacteriocin subtilosin A that possesses antimicrobial activity. Sequence analysis of the sboA gene PCR products showed 97-99% homology to subtilosin A gene cluster of Bacillus subtilis subsp. subtilis strain DSM10. This agar well bioassays using cell-free supernatants revealed that the B. subtilis isolates possess varying antibacterial activities against Escherichia coli, Staphylococcus aureus, Bacillus cereus, and Salmonella enterica ser Typhimurium. The B. subtilis N14 reference strain inhibited S. aureus only. None of the identified isolates was found to inhibit Candida parapsilosis but among the putative B. subtilis isolates, BS3 and MW8.1 showed inhibitory effect against C. parapsilosis. Based on these results, we can say that we were able to identify sboA positive B. subtilis isolates from food and environmental samples capable of inhibiting the Gram-positive and Gram-negative bacteria and yeast tested in the study. The identified isolates can be further investigated for possible application in food biopreservation or as potential sources of antimicrobial peptide for healthcare.

Source or Periodical Title

Asia Life Sciences

ISSN

0117-3375

Volume

25

Issue

1

Page

127-140

Document Type

Article

Physical Description

Illustrations; tables; references

Language

English

Subject

Soil chemistry; Soil composition; Actinobacteria; Bacillus subtilis

En – AGROVOC descriptors

MUNG BEANS; BEAN SPROUTS; SILAGE; SOIL; BACILLUS SUBTILIS; ISOLATION; IDENTIFICATION; BIOASSAYS; ANTIMICROBIAL PROPERTIES; PHILIPPINES

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