Effect of bacterial metabolites on microsporidian Nosema ceranae and on its host Apis mellifera

Abstract

Nosemosis, a disease caused by a microsporidian infection, is one of the most frequently observed parasitic pathologies affecting adult honeybees. Presently, Nosema ceranae seems to be the main microsporidian infection in Apis mellifera. The antibiotic fumagillin is the only compound available to treat Nosema diseases; however, it is no longer licensed in most EU member states; therefore, the need to identify new molecules/substances prevails. The intent of this paper is to test bacterial metabolites by Bacillus and Enterococcus strains, isolated from bee midgut and honey. The toxicity on bees and the antiparasitic activity on N. ceranae were assessed under laboratory conditions. Results did not yield toxicity for the administered surfactin or bacteriocin concentrations. Spores exposed to direct contact with a particular surfactin revealed a significant infectivity reduction when inoculated on bees. This surfactin, administered ad libitum from the individuals' emergence, led to a significant reduction in parasitosis development when bees were infected with untreated spores 7 days postemergence. Based on the results obtained, one of the surfactins is herein postulated as a molecule capable of reducing N. ceranae development, acting either by direct exposure to purified spores or incorporated into the digestive tract of the bee.

Effects of Lactobacillus Johnsonii AJ5 Metabolites on Nutrition, Nosema Ceranae Development and Performance of Apis Mellifera L.

“…In the same way, Corby-Harris et al (2016) discovered an increased resistance to Nosema infection by bees fed a hive bacterium. Concerning bacterial metabolites, Porrini et al (2010) suggested that a surfactin could damage the spore external structure decreasing their viability. Maggi et al (2013) as well proposed a hypothesis about the alteration of microsporidium envelope by an organic acid.…”

“…strain culture (Sabaté et al, 2012) or metabolic products of specific Bacillus spp. (Porrini et al, 2010) and Lactobacillus spp. (Maggi et al, 2013) were administered to bees.…”

Distribution, epidemiological characteristics and control methods of the pathogen Nosema ceranae Fries in honey bees Apis mellifera L. (Hymenoptera, Apidae)

“…It should further be noted that the use of Fumagillin is not yet permitted in the majority of the member states of the European Union due to the high concentration of drug residues in the honey , Porrini et al 2010. A medication needs to be found which does not contaminate the honey, and especially does not affect the health of consumers.…”

“…A medication needs to be found which does not contaminate the honey, and especially does not affect the health of consumers. In this situation, Porrini et al (2010) suggests the use of bacterial metabolites produced by bacteria such as Bacillus and Entorococcus isolated from the mid intestine of the honey bee and from its honey. One possibility is surfactin (a compound produced by B. subtilis), which significantly suppresses the parasite load and does not damage the health of the bee.…”

“…There are also a number of metabolites produced by Lactobacillus johnsonii CRL 1647 (mainly organic acids), which have no toxic effects against honey bees, increase the hive population through the administration of lactic acids, and increase the amount of fatty bodies in the bee; this results in a reduction in pathogen intensity after the second application of organic acid treatment, as well as enhancing the effectiveness of Fumagillin (Maggi et al 2013). Nevertheless, further research is still required to determine the minimum and maximum concentrations to avoid leaving residues in the honey that are harmful to human health (Porrini et al 2010). Furthermore, the possibility of sexual reproduction by these microsporidia species has profound implications for the evolution of their virulence, if they broaden their range of hosts and acquire resistance to the drugs through recombination of their genes (Ironside 2013).…”