Optimization of a cultivation procedure to selectively isolate lactic acid bacteria from insects

Aims Natural niches and transmission routes of lactic acid bacteria (LAB) are highly versatile. Proposed routes of transmission to food fermentations are from plant material via insects or vice versa. This study aimed to establish a method for the selective isolation of LAB from insects. Methods and Results Varied parameters that influence growth and selectivity are temperature, type of carbohydrate and atmosphere. Additionally, the effects of antibiotics to suppress non-LAB species were evaluated. A model consortium consisting of 12 species representing different lifestyles was inoculated in a growth medium to identify conditions for the highest diversity and recovery rate. The method was applied to isolate LAB from Drosophila melanogaster, Sitotroga cerealella, Tribolium castaneum and Tenebrio molitor. Isolated species were Leuconostoc mesenteroides, Paucilactobacillus vaccinostercus and Lactiplantibacillus plantarum from D. melanogaster and L. mesenteroides, Pediococcus pentosaceus and Latilactobacillus curvatus from T. molitor. No LAB could be isolated from T. castaneum and S. cerealella. 16S rDNA amplicon sequencing of DNA obtained from insects corroborated part of our results. Conclusion A combination of different enrichment conditions ensures a high probability to isolate LAB species from insects and can be helpful above already known non-cultivation methods. Significance and Impact of the Study The novel method allows to selectively isolate LAB from insects and the strategy of the method is of interest to study other niches.

Automated summary

This study developed a method for selectively isolating lactic acid bacteria (LAB) from insects, and successfully isolated different species of LAB from Drosophila melanogaster and Tenebrio molitor. The method provides a strategy for studying other niches.