<abstract xmlns="http://www.w3.org/1999/xhtml"><p><italic>Apis mellifera</italic> populations are exposed to different biotic and abiotic stressors that affect bee survival. <italic>Paenibacillus larvae</italic>, the causative agent of American foulbrood, is one of the most important bacterial pathogens that affect bee health. In some countries, the use of antibiotics is the most common method for the prevention and treatment of <italic>P. larvae</italic> infected colonies, however this application can also increase the risk of occurrence of resistant strains. An ecological alternative is the use of vegetal extracts containing bioactive compounds, such as polyphenols. The aim of this study is to check the antimicrobial activity of phenolic extracts of apple pomace, from the cider industry, against <italic>P. larvae</italic> strains by the broth micro dilution method. In addition, the toxicity of the phenolic extracts on <italic>A. mellifera</italic> was verified using the complete exposure method. All extracts contain from 715.31 to 11348.16 μg gal/g DW, determined by Folin-Ciocalteu show antimicrobial activity against <italic>P. larvae</italic> genotype ERIC I, ranging from 23 μg/mL to 150 μg/mL. Toxicity assays of apple pomace extracts on adult bees exhibited a maximum mortality of 18% after 48h. This promising alternative will be used in the future to evaluate its toxicity at a field level.</p></abstract>

Apis mellifera populations are exposed to different biotic and abiotic stressors that affect bee survival. Paenibacillus larvae, the causative agent of American foulbrood, is one of the most important bacterial pathogens that affect bee health. In some countries, the use of antibiotics is the most common method for the prevention and treatment of P. larvae infected colonies, however this application can also increase the risk of occurrence of resistant strains. An ecological alternative is the use of vegetal extracts containing bioactive compounds, such as polyphenols. The aim of this study is to check the antimicrobial activity of phenolic extracts of apple pomace, from the cider industry, against P. larvae strains by the broth micro dilution method. In addition, the toxicity of the phenolic extracts on A. mellifera was verified using the complete exposure method. All extracts contain from 715.31 to 11348.16 μg gal/g DW, determined by Folin-Ciocalteu show antimicrobial activity against P. larvae genotype ERIC I, ranging from 23 μg/mL to 150 μg/mL. Toxicity assays of apple pomace extracts on adult bees exhibited a maximum mortality of 18% after 48h. This promising alternative will be used in the future to evaluate its toxicity at a field level.

Antimicrobial Activity of Phenolic Extract of Apple Pomace against <italic>Paenibacillus larvae</italic> and its Toxicity on <italic>Apis mellifera</italic>

Centro de Investigación en Abejas Sociales, Facultad de Ciencias Exactas y Naturales

Grupo de Investigación de Química Analítica de Productos Naturales, Departamento de Química Analítica, Facultad de Ciencia y Tecnología

Universidad del País Vasco/EuskalHerriko Unibertsitatea (UPV/EHU)

Journal of Apicultural Science

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Antimicrobial Activity of Phenolic Extract of Apple Pomace against  and its Toxicity on 

Apis mellifera populations are exposed to different biotic and abiotic stressors that affect bee survival. Paenibacillus larvae, the causative agent of...

Extract	MIC (μg/mL)	MNIC (μg/mL)	Polyphenols Total (μg gal. Ac./g DW)	% Mortality of A. mellifera

				24 h	48 h
Control	0	0	0	0	2
MR302	23	18	715.31	0	2
MR192	20	15	2512.82	8	14
MR290	79	53	3047.41	6	18
MR300	105	83	3811.49	6	8
MR296	43	28	4508.76	8	16
MR254	125	100	4976.90	4	6
MR256	150	95	6482.20	2	14
MR246	29	23	7056.51	8	20
MR248	106	71	11348.16	6	8

Nº	Sample	Apple varieties	Apple geographical origin	Type of press	Total polyphenols content (μg gal. ac. /g DW)
1	MR302	Tardive (bittervariety)	Asturias (Spain)	Traditional	715.31
2	MR192	Jeptiska, Panenskeceske, Smiricke, Jonathan, Starkinson, Wagnerovo, Sudetskareneta, Ontario, Spartan	Czech Republic	Traditional	2512.82
3	MR290	Durona, Raxao, Collaos and Regona	Asturias (Spain)	Neumatic	3047.41
4	MR300	French varieties with acidic characteristics	France	Neumatic	3811.49
5	MR296	Asturian varieties	Asturias (Spain)	Neumatic	4508.76
6	MR254	30–20% of Basque varieties and 70–80% Asturian varieties	Basque Country (Spain)	Neumatic	4976.90
7	MR256	30–20% of Basque varieties and 70–80% Asturian varieties	Basque Country (Spain)	Neumatic	6482.20
8	MR246	8% of French varieties and, 92% of Asturian varieties	France and / Asturias (Spain)	Traditional	7056.51
9	MR248	70% of Regona	Asturias (Spain)	Neumatic	11348.16

	Control	MR302	MR192	MR290	MR300	MR296	MR254	MR256	MR246	MR248
Control	0
MR302	0.031^*	0
MR192	0.327	0.003^**	0
MR290	0.229	0.001^**	0.825	0
MR300	0.358	0.177	0.064	0.039^*	0
MR296	0.231	0.002^**	0.826	>0.9999	0.040^*	0
MR254	0.555	0.099	0.121	0.076	0.736	0.078	0
MR256	0.788	0.016^*	0.467	0.339	0.237	0.343	0.388	0
MR246	0.013^*	<0.0001^***	0.118	0.175	0.001^**	0.177	0.003^**	0.023^*	0
MR248	>0.999	0.031^*	0.327	0.229	0.358	0.231	0.555	0.788	0.013^*	0

Antimicrobial Activity of Phenolic Extract of Apple Pomace against Paenibacillus larvae and its Toxicity on Apis mellifera

Article Category: Original Article

Published Online: Aug 16, 2020

Page range: 199 - 208

Received: Nov 28, 2018

Accepted: Jun 22, 2020

DOI: https://doi.org/10.2478/jas-2020-0016

Keywords
antimicrobial activity, Apple pomace, phenolic extract

© 2020 Giménez-Martínez Pablo et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1

Antimicrobial activity of the apple pomace phenolic extracts against P. larvae and their toxicity on A. mellifera

Samples of apple pomace from different apple varieties and provided by the Basque cider making industry. The total polyphenols content was measured by Folin-Ciocalteu method (Ramirez-Ambrosi et al., 2013)

Comparison of Survival Curves using the Mantel Cox test for each MIC analyzed in the A. mellifera mortality test (p<0.05)

Antimicrobial Activity of Phenolic Extract of Apple Pomace against Paenibacillus larvae and its Toxicity on Apis mellifera

Article Category: Original Article

Published Online: Aug 16, 2020

Page range: 199 - 208

Received: Nov 28, 2018

Accepted: Jun 22, 2020

DOI: https://doi.org/10.2478/jas-2020-0016

Keywordsantimicrobial activity, Apple pomace, phenolic extract

© 2020 Giménez-Martínez Pablo et al., published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Fig. 1

Antimicrobial activity of the apple pomace phenolic extracts against P. larvae and their toxicity on A. mellifera

Samples of apple pomace from different apple varieties and provided by the Basque cider making industry. The total polyphenols content was measured by Folin-Ciocalteu method (Ramirez-Ambrosi et al., 2013)

Comparison of Survival Curves using the Mantel Cox test for each MIC analyzed in the A. mellifera mortality test (p<0.05)

Keywords
antimicrobial activity, Apple pomace, phenolic extract