Cleto, S.

Simões, M.

Vieira, M. J.

Universidade do Minho: RepositoriUM

1247 BACILLUS CEREUS-SERRATIA PLYMUTHICA TERRITORIAL INTERACTIONS S. Cleto, M. Simões, M.J. Vieira Institute for Biotechnology and Bioengineering, Centre of Biological Engineering, Braga, Portugal Background and aims: Bacteria can release primary and secondary metabolites to the medium, with antimicrobial properties. It was aimed to assess the impact of such S. plymuthica capacity, through chemotaxis, in its co-growth with B. cereus, with glucose-TSB or galactose-SMB as carbon source. Methods: Tryptic soy (TSB) and skim milk (SMB) broth single and mixed B. cereus-S. plymuthica cultures were allowed to grow (24h). Planktonic and biofilm species proportion was analyzed, along with biofilms mass and respiratory activity. Impact of CFU physical proximity on colony morphology and chemotaxis was assessed on 0.7% and 1.3% agar TSA/SMA. Results: The S. plymuthica cell-free spent TSB, but not SMB, generated inhibition halos on B. cereus lawns. Such antimicrobial activity was also detected at single-CFU level, translated in B. cereus negative chemotaxis to the S. plymuthica proximity. This was dependent on both the carbon source/media and agar content, and visually more pronounced on SMA 1.3% (B. cereus swarming favoured). Planktonic co-growth in SMB allowed species coexistence, at levels equal to those in single culture, but in TSB no B. cereus colonies were detected in mixed suspensions or biofilms, with S. plymuthica being found at lower levels. Mixed species biofilms, in TSB, registered higher total mass and respiratory activity than both single biofilms. SMB values were maintained. Conclusions: B. cereus actively responds to S. plymuthica antimicrobial release, with chemotactic levels of response affected by media content and water availability. Studies are being carried out for antimicrobial identification and signalling/response pathway characterization. 

Bacillus cereus-Serratia plymuthica territorial interactions

http://repositorium.sdum.uminho.pt/bitstream/1822/8643/1/1247.pdf

Bacillus cereus-Serratia plymuthica territorial interactions

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Universidade do Minho: RepositoriUM

Universidade do Minho: RepositoriUM