A NEWLY ANTI-Streptococcus suis BACTERIOCIN PRODUCING STRAIN FROM UNWEANED PIGLETS FECAL MATTER: ISOLATION, PRELIMINARY IDENTIFICATION, AND OPTIMIZATION OF MEDIUM COMPOSITION FOR ENHANCED BACTERIOCIN PRODUCTION

Abstract

A newly isolated anti-Streptococcus suis bacteriocin-producing strain LPL1-5 was obtained from healthy unweaned piglets' fecal matter, and was designated as Lactobacillus pentosus LPL1-5 based on morphology, biochemical properties, and 16S rDNA sequencing analysis. The medium composition for enhanced bacteriocin production by L. pentosus LPL1-5 was optimized by statistical methodology. Yeast extract, K₂HPO₄ · 3H₂O, and MnSO₄ · H₂O were identified as significant components influencing pentocin LPL1-5 production using the Plackett–Burman method. Response surface methodology was applied for further optimization. The concentrations of medium components for enhanced pentocin LPL1-5 production were as follows (g/L): lactose 20.00, tryptone 10.00, beef extract 10.00, yeast extract 14.00, MnSO₄ · H₂O 0.84, K₂HPO₄ · 3H₂O 4.92, triammonium citrate 2.00, Na-acetate 5.00, MgSO₄ · 7H₂O 0.58, Tween 80 1.00. Under the optimized condition, a value of 3154.65 ± 27.93 IU/mL bacteriocin activity was achieved, which was 4.2-fold that of the original medium.

Keywords:

• bacteriocin
• isolation
• Lactobacillus pentosus
• optimization
• response surface methodology
• Streptococcus suis

ACKNOWLEDGMENTS

Authors Xiangmei Zhang and Xiaoyuan Chang contributed equally to this work. This research was funded by China Natural Science Foundation (30671482, 31071591), China National 863 Program (2006AA10A208), and China National Science Support Program (2006BAD05A15).

Notes

Note. The codes are for 11 factors of the medium to be optimized: A, lactose (g/L); B, tryptone (g/L); C, beef extract (g/L); D, yeast extract (g/L); E, K₂HPO₄ · 3H₂O (g/L); F, triammonium citrate (g/L); G, Na-acetate (g/L); H, MgSO₄ · 7H₂O (g/L); I, MnSO₄ · H₂O (g/L); J, Tween 80 (g/L); K, NaCl (g/L). Values are mean ± SD of triplicate determinations.

^a 1% significance level.

^b 5% significance level.

Note. Values are mean ± SD of triplicate determinations.

Note. R-squared = 0.9429; Adj-squared = 0.8916.

^a 1% significance level.

^b 5% significance level.