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Overexpression of luxS cannot increase autoinducer-2 production, only affect the growth and biofilm formation in Streptococcus suis.

Wang Y, Yi L, Zhang Z, Fan H, Cheng X, Lu C - ScientificWorldJournal (2013)

Bottom Line: In our previous study, the function of LuxS in AI-2 production was verified in Streptococcus suis (SS).An SS strain that overexpressed luxS was constructed to comprehensively understand the function of AI-2.Thus, AI-2 production is not correlated with luxS transcription. luxS expression is constitutive, but the transcription of pfs is perhaps correlated with AI-2 production in SS.

View Article: PubMed Central - PubMed

Affiliation: College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471003, China ; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China ; OIE Reference Laboratory for Swine Streptococcosis, Nanjing 210095, China.

ABSTRACT
LuxS/AI-2 quorum sensing (QS) system involves the production of cell signaling molecules via luxS-based autoinducer-2 (AI-2). LuxS has been reported to plays critical roles in regulating various behaviors of bacteria. AI-2 is a byproduct of the catabolism of S-adenosylhomocysteine (SAH) performed by the LuxS and Pfs enzymes. In our previous study, the function of LuxS in AI-2 production was verified in Streptococcus suis (SS). Decreased levels of SS biofilm formation and host-cell adherence as well as an inability to produce AI-2 were observed in bacteria having a luxS mutant gene. In this study, the level of AI-2 activity exhibits a growth-phase dependence with a maximum in late exponential culture in SS. An SS strain that overexpressed luxS was constructed to comprehensively understand the function of AI-2. Overexpressed luxS was not able to increase the level of pfs expression and produce additional AI-2, and the bacteria were slower growing and produced only slightly more biofilm than the wild type. Thus, AI-2 production is not correlated with luxS transcription. luxS expression is constitutive, but the transcription of pfs is perhaps correlated with AI-2 production in SS.

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Quantitative determination of biofilm formation of the different strains. All strains were cultured in THB medium supplemented with 1% fibrinogen. Each strain was tested in 8-wells of a 96-well microtiter plate. Time course of biofilm formation of the different strains for 24 h or 48 h. HA9801, ΔluxS, CΔluxS, and luxS+ refer to the WT strain, the luxS mutant strain, the complementation strain, and the overexpression strain. The biofilm formation by the ΔluxS was significantly decreased compared to that of the WT strain (P < 0.01). The luxS+ overexpression strain was slightly increased to those of the WT strain and CΔluxS. Negative control (NC) wells contained broth only. The columns represent the means and standard deviations of four or more experiments. The asterisk showed significant difference (P < 0.05).
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fig4: Quantitative determination of biofilm formation of the different strains. All strains were cultured in THB medium supplemented with 1% fibrinogen. Each strain was tested in 8-wells of a 96-well microtiter plate. Time course of biofilm formation of the different strains for 24 h or 48 h. HA9801, ΔluxS, CΔluxS, and luxS+ refer to the WT strain, the luxS mutant strain, the complementation strain, and the overexpression strain. The biofilm formation by the ΔluxS was significantly decreased compared to that of the WT strain (P < 0.01). The luxS+ overexpression strain was slightly increased to those of the WT strain and CΔluxS. Negative control (NC) wells contained broth only. The columns represent the means and standard deviations of four or more experiments. The asterisk showed significant difference (P < 0.05).

Mentions: The abilities of the wild type, mutant, complementation, and overexpression strains to develop biofilms in 96-well microtiter plates were determined using the Crystal Violet (CV) assay (Figure 4). When these plates were incubated under the same culture conditions at 37°C for 24 h without agitation, the WT strain HA9801 formed considerably more biomass (OD595, 0.69 ± 0.11) than the luxS mutant strain (OD595, 0.50 ± 0.08) (P < 0.01). Furthermore, the biofilm formed by the luxS+ overexpression strain (OD595, 0.76 ± 0.12) was slightly increased to those of the WT strain HA9801 and the complementation strain (Figure 4).


Overexpression of luxS cannot increase autoinducer-2 production, only affect the growth and biofilm formation in Streptococcus suis.

Wang Y, Yi L, Zhang Z, Fan H, Cheng X, Lu C - ScientificWorldJournal (2013)

Quantitative determination of biofilm formation of the different strains. All strains were cultured in THB medium supplemented with 1% fibrinogen. Each strain was tested in 8-wells of a 96-well microtiter plate. Time course of biofilm formation of the different strains for 24 h or 48 h. HA9801, ΔluxS, CΔluxS, and luxS+ refer to the WT strain, the luxS mutant strain, the complementation strain, and the overexpression strain. The biofilm formation by the ΔluxS was significantly decreased compared to that of the WT strain (P < 0.01). The luxS+ overexpression strain was slightly increased to those of the WT strain and CΔluxS. Negative control (NC) wells contained broth only. The columns represent the means and standard deviations of four or more experiments. The asterisk showed significant difference (P < 0.05).
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3842066&req=5

fig4: Quantitative determination of biofilm formation of the different strains. All strains were cultured in THB medium supplemented with 1% fibrinogen. Each strain was tested in 8-wells of a 96-well microtiter plate. Time course of biofilm formation of the different strains for 24 h or 48 h. HA9801, ΔluxS, CΔluxS, and luxS+ refer to the WT strain, the luxS mutant strain, the complementation strain, and the overexpression strain. The biofilm formation by the ΔluxS was significantly decreased compared to that of the WT strain (P < 0.01). The luxS+ overexpression strain was slightly increased to those of the WT strain and CΔluxS. Negative control (NC) wells contained broth only. The columns represent the means and standard deviations of four or more experiments. The asterisk showed significant difference (P < 0.05).
Mentions: The abilities of the wild type, mutant, complementation, and overexpression strains to develop biofilms in 96-well microtiter plates were determined using the Crystal Violet (CV) assay (Figure 4). When these plates were incubated under the same culture conditions at 37°C for 24 h without agitation, the WT strain HA9801 formed considerably more biomass (OD595, 0.69 ± 0.11) than the luxS mutant strain (OD595, 0.50 ± 0.08) (P < 0.01). Furthermore, the biofilm formed by the luxS+ overexpression strain (OD595, 0.76 ± 0.12) was slightly increased to those of the WT strain HA9801 and the complementation strain (Figure 4).

Bottom Line: In our previous study, the function of LuxS in AI-2 production was verified in Streptococcus suis (SS).An SS strain that overexpressed luxS was constructed to comprehensively understand the function of AI-2.Thus, AI-2 production is not correlated with luxS transcription. luxS expression is constitutive, but the transcription of pfs is perhaps correlated with AI-2 production in SS.

View Article: PubMed Central - PubMed

Affiliation: College of Animal Science and Technology, Henan University of Science and Technology, Luoyang 471003, China ; Key Lab of Animal Bacteriology, Ministry of Agriculture, Nanjing Agricultural University, Nanjing 210095, China ; OIE Reference Laboratory for Swine Streptococcosis, Nanjing 210095, China.

ABSTRACT
LuxS/AI-2 quorum sensing (QS) system involves the production of cell signaling molecules via luxS-based autoinducer-2 (AI-2). LuxS has been reported to plays critical roles in regulating various behaviors of bacteria. AI-2 is a byproduct of the catabolism of S-adenosylhomocysteine (SAH) performed by the LuxS and Pfs enzymes. In our previous study, the function of LuxS in AI-2 production was verified in Streptococcus suis (SS). Decreased levels of SS biofilm formation and host-cell adherence as well as an inability to produce AI-2 were observed in bacteria having a luxS mutant gene. In this study, the level of AI-2 activity exhibits a growth-phase dependence with a maximum in late exponential culture in SS. An SS strain that overexpressed luxS was constructed to comprehensively understand the function of AI-2. Overexpressed luxS was not able to increase the level of pfs expression and produce additional AI-2, and the bacteria were slower growing and produced only slightly more biofilm than the wild type. Thus, AI-2 production is not correlated with luxS transcription. luxS expression is constitutive, but the transcription of pfs is perhaps correlated with AI-2 production in SS.

Show MeSH
Related in: MedlinePlus