Probiotic bacteria struggle to survive in silkworm guts, complicating farm treatment plans
A new study finds that beneficial bacteria added to silkworm feed vanish within days, limiting their usefulness as a disease treatment in commercial operations. The findings suggest that for probiotics to work in silk production, researchers will need to develop new delivery methods or stronger bacterial strains.
Originaltitel: In vivo survivability and storage longevity of Lactobacillus casei for treatment of Bombyx mori silkworms
<p>It has previously been shown that bacteria belonging to the genus Lactobacillus can enhance survival of infected silkmoths. To explore the feasibility of probiotic treatment in a production setting, we investigated the survival of the commercial lactic acid bacterium Lactobacillus casei TISTR1463 in vivo (in silkworm midgut) and in vitro (during storage). Mulberry leaves, dipped in a solution of Lactobacillus casei TISTR1463, were fed to 1st instar silkworm larvae. DNA was extracted from larval midgut tissue and the persistence of L. casei was investigated by PCR. The result showed that L. casei could be detected in the first instar larvae at 1 and 3 days after probiotic ingestion, but not in successive instars. Also, was evaluated the viability of L. casei as powder formula developed with three different protocols: Freeze drying, Foaming-mat drying, and Fan drying. Different drying methods resulted in distinct physical characteristics of the probiotic powder. Viability after drying was similar and much higher for Freeze drying and Fan drying as compared to Foaming-mat drying. Fan drying was then selected for storage survival analysis because it represents a simple and low-cost method with potential applicability under practical field conditions. L. casei in powder form remained viable for up to 12 weeks when stored at 5 degrees C, indicating that storing the bacteria as a dried product is feasible.</p><p>This study showed that it is possible to store probiotics in a production setting, but that the longevity of probiotics in the gut of the silkworms needs to be prolonged.</p>