ABSTRACT
Objective To investigate the antibacterial effect of selected lactic acid bacteria (LAB) biofilms on the planktonic and biofilm population of methicillin-resistant Staphylococcus aureus (MRSA) (S547). Methods In this study, biofilm-forming LAB were isolated from tairu and kefir. Isolate Y1 and isolate KF were selected based on their prominent inhibition against test pathogens (using spot-on-agar method and agar-well-diffusion assay) and efficient biofilm production (using tissue culture plate method). They were then identified as Lactobacillus casei (L. casei) Y1 and Lactobacillus plantarum (L. plantarum) KF, respectively using 16S rDNA gene sequencing. The influence of incubation time, temperature and aeration on the biofilm production of L. casei Y1 and L. plantarum KF was also investigated using tissue culture plate method. The inhibitory activity of both the selected LAB biofilms was evaluated against MRSA (Institute for Medical Research code: S547) using L. plantarum ATCC 8014 as the reference strain. Results L. casei Y1 showed the highest reduction of MRSA biofilms, by 3.53 log at 48 h while L. plantarum KF records the highest reduction of 2.64 log at 36 h. In inhibiting planktonic population of MRSA (S547), both L. casei Y1 and L. plantarum KF biofilms recorded their maximum reduction of 4.13 log and 3.41 log at 24 h, respectively. Despite their inhibitory effects being time-dependent, both LAB biofilms exhibited good potential in controlling the biofilm and planktonic population of MRSA (S547). Conclusions The results from this study could highlight the importance of analysing biofilms of LAB to enhance their antibacterial efficacy. Preferably, these protective biofilms of LAB could also be a better alternative to control the formation of biofilms by pathogens such as MRSA.
ABSTRACT
Aims: Dietary intake of conjugated linoleic acid (CLA) by human is insufficient to exhibit properties of anti-cancer, antiinflammatory, anti-atherosclerosis, anti-obesity and enhancing immune system. Thus, enrichment of CLA in chicken by bacteria is a suggestion to solve the problem. It would be an advantage to have bacteria capable of producing CLA and has probiotic potential in chicken. Thus, probiotic properties of CLA-producing bacteria were accessed in this study. Methodology and results: In this study, 47 lactic acid bacteria (LAB) isolated from gastrointestinal tract of chickens were screened for conjugated linoleic acid (CLA) production. Lactobacillus salivarius strain P2, Enterococcus faecium strain P1 and Lactobacillus agilis strain P3 were shown to produce 21.97, 23.35 and 31.08 µg/mL of CLA in MRS broth containing free linoleic acid (0.5 mg/mL) and 2% (w/v) Tween 80, respectively. Lactobacillus salivarius strain P2, E. faecium strain P1 and L. agilis strain P3 were found to be able to tolerate 0.3% oxgall (Difco, France) and pH 2.5. Lactobacillus agilis strain P3 and L. salivarius strain P2 showed better acid tolerance compared to E. faecium strain P1. Besides that, L. agilis strain P3 and L. salivarius strain P2 were resistant to two out of eight types of antibiotics tested, able to produce 220.04 mM lactic acid and 200.17 mM of lactic acid, respectively. Enterococcus faecium strain P1 was resistant to five out of eight types of antibiotic tested, produced 90.39 mM lactic acid and showed hemolytic activity. Only L. agilis strain P3 can produce acetic acid at a concentration of 2.71 mM. Conclusion, significance and impact of study: These results showed that the CLA-producing L. salivarius strain P2 and L. agilis strain P3 could be potential probiotic bacteria for chickens, which may eventually lead to production of chicken with better meat quality.