The aim of this study was to test the antimicrobial, anti-adhesive and anti-biofilm activities of a rhamnolipid extracted from Pseudomonas aeruginosa UKMP14T previously isolated from oil contaminated soil in Malaysia against ESKAPE (i.e. multidrug resistant) pathogens. Zones of inhibition in an agar well diffusion assay were observed at 50 μg mL−1 concentrations of rhamnolipid for all the ESKAPE bacteria. The MIC and MBC values ranged between 7.81–62.5 µg mL−1 and 31.25–1000 µg mL−1, respectively. Percent killing was recorded to be more than 90% except for Klebsiella pneumoniae (86.84%). Furthermore, anti-adhesion studies showed that there was 76% hindrance in attachment of E. faecium and 91% in Acinetobacter baumannii at 4xMIC. The highest inhibition in adhesion was found at 4xMIC, which was 46% for A. baumannii and 62% for Enterococcus faecium. Finally, the anti-biofilm capability of the rhamnolipid was determined which ranged between 25%-76% in A. baumannii and 35%-88% in E. faecium. To the best of our knowledge, this is the first study to include research on antimicrobial, anti-adhesive and anti-biofilm activities of rhamnolipid from the local isolate P. aeruginosa UKMP14T against ESKAPE bacteria. Obtained results suggest that this rhamnolipid can be exploited commercially for the production of novel antibiotics.
Screening of new source of novel and industrially useful enzymes is a key research pursuit in enzyme biotechnology. The study aims to report the characteristics of novel thermophilic microorganisms isolated from Sungai Klah (SK) Hot Spring, Perak, Malaysia, that can produce α-amylase. The morphological and biochemical properties were examined for SUNGC2 sample. The isolate was further screened for amylase, followed by 16S rRNA and analytical profile index (API) test. This isolate was further subjected to pH optimisation for α-amylase production. It was found that SUNGC2 was an α-amylase producer and was identified as Bacillus licheniformis SUNGC2 with NCBI accession numbers MH062901. The enzyme was found to exhibit an optimum temperature of 50°C and a pH of 7.0. The relative activity of the enzyme was obtained based on the improvement of the culture conditions. The highest amount of amylase production was 24.65 U/mL at pH 7.0, consecutively the growth was also highest at pH 7.0 with a 9.45-fold increase in specific activity by ammonium phosphate precipitation of 80% (w/v). The results showed that the bacteria isolated from the hot spring are a significant source of thermophilic enzymes that are highly promising in biotechnology.
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