An ELISA for the detection of Bacillus subtilis L-form bacteria confirms their symbiosis in strawberry

Aims: To develop an ELISA for the detection of antigens derived from stable Bacillus subtilis L-form bacteria and to detect these in plants injected w ith L-form bacteria. Methods and Results: A sandwich ELISA was developed and its specificity was investigated using L-forms and cell-walled forms of B. subtilis, different Bacillus species and a range of bacteria isolated from glasshouse-grown st rawberry plants. The detection limits of the ELISA were approximately 10(3) viable cells ml(-1) for L-forms compared with 10(7) viable cells ml(-1) fo r cell-walled forms. Results showed that L-forms survived and moved within strawberry tissues injected with L-form bacteria. Conclusion: An ELISA that selectively detects B. subtilis L-form bacteria w as developed and shown to confirm the presence of L-forms in plants. Significance and Impact of the Study: This will be a valuable rapid method to further studies on L-form plant interactions.