STUDY ON ANTIMICROBIAL EFFICACY OF Lactobacillus SPECIES FROM CHICKEN AGAINST Clostridium perfringens AND E. coli
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Date
2022-03
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
A study was carried out on the isolation, molecular characterization and
probiotic potency which includes antibacterial activity of Lactobacillus spp. isolated
from healthy chicken against Clostridium perfringens and E. coli.
A total of 73 samples from desi and commercial chicken were collected of
which 50 were cloacal swabs and 23 were tissues, from which 56 (76.71%) isolates
were obtained. Tissues (87.5%) have an increased incidence of Lactobacillus spp. than
cloacal swabs (70%).
The percentage of autoaggregation of 56 isolates increased significantly over
time from 5.03 % - 77.33 % at 4 hours to 10.37 % - 82.29 % after 24 hours of
incubation. The cell surface hydrophobicity of the 56 isolates ranged from 6.3 % to
90.68 % for xylene and 18.13 % to 95.84 % for n-hexadecane. Isolates exhibited high
percentage of hydrophobicity to n-hexadecane when compared to xylene.
Based on autoaggregation and hydrophobicity results 22 isolates were chosen.
All the 22 isolates demonstrated viable colonies at all ox-bile concentrations (0.1 %, 0.3
% and 0.5 %) after 2 and 4 hours of incubation, however after 6 hours of incubation,
viability varied. In the acid tolerance assay, majority of the isolates showed viability at
pH 3 and all the isolates demonstrated viability at pH 6.5.
Based on bile and acid viability results 16 isolates were selected for further tests.
All these 16 isolates inhibited Clostridium perfringens with zone of inhibition ranging
from 11mm-22mm and 10mm-20mm anaerobically and aerobically, respectively.
Whereas, the zone of inhibition of E. coli ranged from 10mm-18mm in agar well
diffusion assay. In the antibiofilm assay, all 16 isolates developed biofilm and reduced
E. coli biofilm formation.
The antibiotic resistance pattern of 16 isolates revealed 100% resistance to
Nalidixic acid and Vancomycin, 93.75 % resistance to Tetracycline and Streptomycin,
75 % resistance to Ciprofloxacin and Gentamicin, 66.66 % resistance to Cotrimoxazole,
25 % resistance to Nitrofurantoin, 6.25 % resistance to Clindamycin and
Cefaclor and 0 % resistance to Chloramphenicol, Ampicillin and Erythromycin. The
hemolysis test for the 16 isolates indicated a complete hemolysis for 14, partial
hemolysis for one and no hemolysis for one isolate, whereas all the isolates showed
negative reaction for gelatin hydrolysis test.
Based on the results of probiotic potency and safety assays, one isolate was
finally chosen from the 56 isolates. The isolate sequence revealed 96.82% of its
similarity to Lactobacillus fermentum. The present study concluded that selected Lactobacillus fermentum has potential
probiotic properties with good antimicrobial activity against Clostridium perfringens
and E. coli hence, may be tested in vivo in poultry as an alternative to antibiotics.
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