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Effect of Chitosan Acetate on Bacteria Occurring on Neungee Mushrooms, Sarcodon aspratus.

Park BS, Koo CD, Ka KH, Lee YN - Mycobiology (2008)

Bottom Line: Survival fractions of the MK1 and S strains at the MIC were 3 × 10(-4) and 1.4 × 10(-3) after 24 h, and 2 × 10(-4) and 7 × 10(-4) after 48 h, respectively.Thirty-eight percent of Neungee pieces treated in a 0.06% chitosan acetate solution for 2~3 second did not show any bacterial growth at 4 days, whereas bacterial growth around untreated mushroom pieces occurred within 2 days.These data suggest that chitosan acetate is highly effective in controlling growth of indigenous microorganisms on Neungee.

View Article: PubMed Central - PubMed

Affiliation: Division of Life Science, Chungbuk National University, Cheongju 361-763, Korea.

ABSTRACT
Minimal growth inhibitory concentrations (MICs) of chitosan acetate (M.W. 60 kDa) on heterotrophic bacteria (strains MK1, S, and R) isolated from the soft-rotten tissues of Neungee mushroom (Sarcodon aspratus) were measured. The slimy substance produced by the MK1 strain was responsible for the diseased mushroom's appearance. The S and R strains were members of the Burkholderia cepacia complex. These strains showed different levels of susceptibility toward chitosan acetate. The MIC of chitosan acetate against the MK1 and S strains was 0.06%. The MIC against the R strain was greater than 0.10%. Survival fractions of the MK1 and S strains at the MIC were 3 × 10(-4) and 1.4 × 10(-3) after 24 h, and 2 × 10(-4) and 7 × 10(-4) after 48 h, respectively. Survival fractions of the R strain after 24 and 48 hr at 0.1% chitosan acetate were 1 × 10(-2) and 6.9 × 10(-3), respectively. Compared to the MK1 and S strains, the low susceptibility of the R stain towards chitosan acetate could be due to the ability of the R strain to utilize chitosan as a carbon source. Thirty-eight percent of Neungee pieces treated in a 0.06% chitosan acetate solution for 2~3 second did not show any bacterial growth at 4 days, whereas bacterial growth around untreated mushroom pieces occurred within 2 days. These data suggest that chitosan acetate is highly effective in controlling growth of indigenous microorganisms on Neungee. The scanning electron micrographs of the MK1 strain treated with chitosan revealed a higher degree of disintegrated and distorted cellular structures.

No MeSH data available.


Related in: MedlinePlus

Growth of the MK1 strain at different concentrations of chitosan acetate in LB broth. This figure was a representative result among three separate experiments.
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Figure 2: Growth of the MK1 strain at different concentrations of chitosan acetate in LB broth. This figure was a representative result among three separate experiments.

Mentions: The R and S strains, the member of Burkholderia cepacia complex, seemed to be associated less frequently with the soft tissue of Neungee mushrooms because these bacteria are very common in nature. However, it has been claimed that the MK1 strain, which produces a copious mucoid substance, seemed to be more responsible for the diseased appearance of Neugnee mushrooms (Lee and Koo, 2007). The growth curve of the MK1 strain in the LB medium containing different concentrations of chitosan acetate, as shown in Fig. 2, suggested that its growth was significantly affected by chitosan. The growth rate of MK1 in the presence of 0.04% chitosan dropped to 0.064 h-1 compared to 0.223 h-1 in the absence of chitosan. The delayed growth of MK1 in the presence of chitosan probably resulted in the prolonged time period prior to entering stationary phase. The optical density of the MK1 culture containing 0.06% chitosan showed only an insignificant increase up to 36 hours and thereafter remained constant. This slow increase in optical density likely resulted from either the growth of MK1 prior to responding to antimicrobial action of chitosan or the exopolysaccharide (EPS) released from the MK1 cells due to the effectivenss of chitosan. We determined the MIC of chitosan acetate against MK1 as 0.06% (v/v). The growth rates of the S strain in the presence of 0.02 and 0.04% chitosan (0.152 h-1 and 0.145 h-1, respectively) were rather similar to each other, despite the growth in the stationary phase quite differed from each other (Fig. 3). The S strain in the presence of 0.04% chitosan entered the stationary phase at 18 hours; thereafter, a slight but steady increase in optical density suggested the S strain gained tolerance toward chitosan following exposure. Since there was no bacterial growth in the presence of 0.06% chitosan for the length of the culture time tested, this concentration was considered as the MIC toward the S strain. Although the R and S strains were identified as members of the Burkhoderlia cepacia complex (Lee and Koo, 2007), the growth patterns of these strains in the presence of chitosan acetate were dissimilar, as shown in Fig. 3 and 4. The R strain showed a fair amount of growth at both 0.06 and 0.08% chitosan, although the amount of growth and rate were somewhat reduced at increased chitosan concentrations (Fig. 4). Steady growth of R occurred even at 0.1% chitosan, suggesting resistance of the R stain to chitosan and the possibility that chitosan was acting as a carbon source for R growth.


Effect of Chitosan Acetate on Bacteria Occurring on Neungee Mushrooms, Sarcodon aspratus.

Park BS, Koo CD, Ka KH, Lee YN - Mycobiology (2008)

Growth of the MK1 strain at different concentrations of chitosan acetate in LB broth. This figure was a representative result among three separate experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3755204&req=5

Figure 2: Growth of the MK1 strain at different concentrations of chitosan acetate in LB broth. This figure was a representative result among three separate experiments.
Mentions: The R and S strains, the member of Burkholderia cepacia complex, seemed to be associated less frequently with the soft tissue of Neungee mushrooms because these bacteria are very common in nature. However, it has been claimed that the MK1 strain, which produces a copious mucoid substance, seemed to be more responsible for the diseased appearance of Neugnee mushrooms (Lee and Koo, 2007). The growth curve of the MK1 strain in the LB medium containing different concentrations of chitosan acetate, as shown in Fig. 2, suggested that its growth was significantly affected by chitosan. The growth rate of MK1 in the presence of 0.04% chitosan dropped to 0.064 h-1 compared to 0.223 h-1 in the absence of chitosan. The delayed growth of MK1 in the presence of chitosan probably resulted in the prolonged time period prior to entering stationary phase. The optical density of the MK1 culture containing 0.06% chitosan showed only an insignificant increase up to 36 hours and thereafter remained constant. This slow increase in optical density likely resulted from either the growth of MK1 prior to responding to antimicrobial action of chitosan or the exopolysaccharide (EPS) released from the MK1 cells due to the effectivenss of chitosan. We determined the MIC of chitosan acetate against MK1 as 0.06% (v/v). The growth rates of the S strain in the presence of 0.02 and 0.04% chitosan (0.152 h-1 and 0.145 h-1, respectively) were rather similar to each other, despite the growth in the stationary phase quite differed from each other (Fig. 3). The S strain in the presence of 0.04% chitosan entered the stationary phase at 18 hours; thereafter, a slight but steady increase in optical density suggested the S strain gained tolerance toward chitosan following exposure. Since there was no bacterial growth in the presence of 0.06% chitosan for the length of the culture time tested, this concentration was considered as the MIC toward the S strain. Although the R and S strains were identified as members of the Burkhoderlia cepacia complex (Lee and Koo, 2007), the growth patterns of these strains in the presence of chitosan acetate were dissimilar, as shown in Fig. 3 and 4. The R strain showed a fair amount of growth at both 0.06 and 0.08% chitosan, although the amount of growth and rate were somewhat reduced at increased chitosan concentrations (Fig. 4). Steady growth of R occurred even at 0.1% chitosan, suggesting resistance of the R stain to chitosan and the possibility that chitosan was acting as a carbon source for R growth.

Bottom Line: Survival fractions of the MK1 and S strains at the MIC were 3 × 10(-4) and 1.4 × 10(-3) after 24 h, and 2 × 10(-4) and 7 × 10(-4) after 48 h, respectively.Thirty-eight percent of Neungee pieces treated in a 0.06% chitosan acetate solution for 2~3 second did not show any bacterial growth at 4 days, whereas bacterial growth around untreated mushroom pieces occurred within 2 days.These data suggest that chitosan acetate is highly effective in controlling growth of indigenous microorganisms on Neungee.

View Article: PubMed Central - PubMed

Affiliation: Division of Life Science, Chungbuk National University, Cheongju 361-763, Korea.

ABSTRACT
Minimal growth inhibitory concentrations (MICs) of chitosan acetate (M.W. 60 kDa) on heterotrophic bacteria (strains MK1, S, and R) isolated from the soft-rotten tissues of Neungee mushroom (Sarcodon aspratus) were measured. The slimy substance produced by the MK1 strain was responsible for the diseased mushroom's appearance. The S and R strains were members of the Burkholderia cepacia complex. These strains showed different levels of susceptibility toward chitosan acetate. The MIC of chitosan acetate against the MK1 and S strains was 0.06%. The MIC against the R strain was greater than 0.10%. Survival fractions of the MK1 and S strains at the MIC were 3 × 10(-4) and 1.4 × 10(-3) after 24 h, and 2 × 10(-4) and 7 × 10(-4) after 48 h, respectively. Survival fractions of the R strain after 24 and 48 hr at 0.1% chitosan acetate were 1 × 10(-2) and 6.9 × 10(-3), respectively. Compared to the MK1 and S strains, the low susceptibility of the R stain towards chitosan acetate could be due to the ability of the R strain to utilize chitosan as a carbon source. Thirty-eight percent of Neungee pieces treated in a 0.06% chitosan acetate solution for 2~3 second did not show any bacterial growth at 4 days, whereas bacterial growth around untreated mushroom pieces occurred within 2 days. These data suggest that chitosan acetate is highly effective in controlling growth of indigenous microorganisms on Neungee. The scanning electron micrographs of the MK1 strain treated with chitosan revealed a higher degree of disintegrated and distorted cellular structures.

No MeSH data available.


Related in: MedlinePlus