Fructophilic Lactic Acid Bacteria for Honey Bee Health

Akihito ENDO

Faculty of Bioindustry, Tokyo University of Agriculture

Pollination is an important event to keep nature and to produce food for animals. Both wild and commercially managed bees are the predominant pollinators in most regions, and over 70 % of the major 100 crop species are bee-pollinated based on estimation by FAO. Bees are thus crucial insects for human beings. On the other hand, the bees have a constant decline during the past decades, and, in US, 60 % of honey bee colonies disappeared during the last 60 years (UNEP 2010). Possible reasons for the honey bee disappearance would be mites, pesticides, pathogens, etc. Foulbrood is a serious disease of honey bee larvae and is a notifiable disease. Two pathogens, i.e. Paenibacillus larvae and Melissococcus plutonius, are reported as the foulbrood pathogens. To control these pathogens, antibiotics are used in several countries, including US and Japan. However, several concerns related to the daily usage of antibiotics have been reported in the countries, including accumulation of antibiotics-resistance genes and residual antibiotics in honey bee related human diet (Tian et al., 2012).

            Honey bees consume specific diet mainly related to pollen, and this diet results in specific microbiota in guts. Bifidobacteria, lactic acid bacteria and acetic acid bacteria are predominant microbes in honey bee guts. Fructophilic lactic acid bacteria (FLAB), a group of lactic acid bacteria which prefer fructose over glucose as a growth substrate, are major components in the predominant microbe group. Fructobacillus spp. and a few lactobacilli are included in the interesting microbial group. These organisms can be seen in flowers, fruits, fermented fruits and fructose-consuming insect guts. Genomic and biochemical analysis of FLAB species revealed that fructose-richness induced an environment-specific gene reduction in phylogenetically distant microorganisms (Maeno et al., 2016).

A former study revealed that Lactobacillus kunkeei and Fructobacillus fructosus are major FLAB species in both adult and larvae guts (Endo et al., 2013). These species are shared in honey bee nests at the strain level. Several FLAB species showed strong antagonistic activity against foulbrood pathogens, and this activity would be due to production of acids and bacteriocins. Certain FLAB species possess growth promoting activity of bee commensal lactobacilli and bifidobacteria, which could be helpful to keep well balanced microbiota in honey bee guts. These characteristics shed light to FLAB as potential honey bee probiotics. Further researches will be conducted to characterize beneficial properties in FLAB.

References

Endo A, Salminen S. Honeybees and beehives are rich sources for fructophilic lactic acid bacteria. Syst Appl Microbiol. 2013 36: 444-448

Maeno S, Tanizawa Y, Kanesaki Y, Kubota E, Kumar H, Dicks L, Salminen S, Nakagawa J, Arita M, Endo A. Genomic characterization of a fructophilic bee symbiont Lactobacillus kunkeei reveals its niche-specific adaptation. Syst Appl Microbiol. 2016 39: 516-526.

UNEP 2010 - UNEP Emerging Issues: Global Honey Bee Colony Disorder and Other Threats to Insect Pollinators.

Tian B, Fadhil NH, Powell JE, Kwong WK, Moran NA. Long-term exposure to antibiotics has caused accumulation of resistance determinants in the gut microbiota of honeybees. MBio 2012 30: e00377-12.