Earticle

초록

영어

Lactic acid bacteria (LAB) producing phenyllactic acid (PLA), which is known as antimicrobial compound, was isolated from button mushroom bed and the isolated LAB was identified to Lactobacillus casei by 16 rRNA gene sequence analysis. Cell-free supernatant (CFS) from L. casei was assessed for both the capability to produce the antimicrobial compound PLA and the antifungal activity against three fungal pathogens (Rhizoctonia solani, Botrytis cinerea, and Collectotricum aculatum). PLA concentration was investigated to be 3.23 mM in CFS when L. casei was grown in MRS broth containing 5 mM phenylpyruvic acid as precursor for 16 h. Antifungal activity demonstrated that all fungal pathogens were sensitive to 5% CFS (v/v) of L. casei with average growth inhibitions ranging from 34.58% to 65.15% (p < 0.005), in which R. solani was the most sensitive to 65.15% and followed by C. aculatum, and B. cinerea. The minimum inhibitory concentration (MIC) for commercial PLA was also investigated to show the same trend in the range of 0.35 mg mL-1 (2.11 mM) to 0.7 mg mL-1 (4.21 mM) at pH 4.0. The inhibition ability of CFS against the pathogens were not affected by the heating or protease treatment. However, pH modification in CFS to 6.5 resulted in an extreme reduction in their antifungal activity. These results may indicate that antifungal activities in CFS was caused by acidic compounds like PLA or organic acids rather than protein or peptide molecules.

목차

ABSTRACT
 Introduction
 Materials and methods
  Microorganisms and culture media
  Identification of LAB
  Preparation of cell-free supernatants (CFS)
  Identification of PLA
  Determination of antifungal activity
  Statistical analysis
 Results and Discussion
  Isolation and identification of PLA producing LAB
  Cell growth
  Inhibitory effect of CFS against fungal pathogens
 Conclusions
 References

저자

• Jeoung Ah Yoo [ Department of Bio-Environmental Chemistry, College of Agriculture and Life Sciences, Chungnam National University ]
• Chan-Jung Lee [ Mushroom Research Division, National Institute of Horticultural & Herbal Science, RDA, Eumseong, Chungbuk 27712, Korea ]
• Yong-Gyun Kim [ Crop Research Division, Chungcheongnam-do Agricultural Research & Extension Services, Yesan 32418, Korea ]
• Byung-Eui Lee [ Department of Chemistry, College of Natural Sciences, Soonchunghyang University, Asan 31538, Korea ]
• Min-Ho Yoon [ Department of Bio-Environmental Chemistry, College of Agriculture and Life Sciences, Chungnam National University ] Corresponding author

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