The Antimicrobial Potential of Bacteria Isolated from Honey Samples Produced in the Apiaries Located in Pomeranian Voivodeship in Northern Poland

Abstract

The principal objective of this study was to determine whether the honeys produced in apiaries located in Pomeranian Voivodeship (Northern Poland) contain bacteria producing metabolites with growth inhibition potential against important human and animal pathogens. The pathogens included Staphylococcus aurues, Staphyloccocus epidermidis, Escherichia coli, Listeria monocytogenes, Pseudomonas aeruginosa, and Candida albicans. From 12 samples of honey, 163 strains of bacteria were isolated. Activity against reference staphylococci: S. aurues ATCC 25923; S. aureus ATCC 29213; S. epidermidis 12228 was observed in 33 (20.3%), 38 (23.3%), and 41 (25.1%) isolates, respectively. High inhibitory activity was also found against Listeria monocytogenes ATCC 7644 in 34 strains (20.9%). Activity against Candida albicans ATCC 10231 and especially Gram-negative bacteria: Pseudomonas aeruginosa ATCC 27857 and Escherichia coli ATCC 25922 was rarely observed. Production of metabolites exhibiting activity against the three pathogens mentioned above was confirmed for 13 (7.8%), 3 (1.8%), and 2 (1.2%) isolates, respectively. Forty-six isolates were selected for further analysis. Within this group, metabolites synthesized by 18 producing strains (39.13%) inhibited growth of only one of the reference strains of pathogenic microorganisms. However, 14 (30.44%), 8 (17.39%), and 6 (13.04%) strains produced agents active against three, two, and four pathogens, respectively. Sequencing of the 16S rRNA gene revealed that 80.4% of these 46 producing strains belong to the genus Bacillus. However, some producing strains belonging to the genus of Peanibacillus, Lysinibacillus, Microbacterium, and Staphylococcus were also identified. Furthermore, the analysis of the sequences of 16S rRNA, as well as RAPD-PCR, exhibited a significant diversity in the strains tested, even in the case of bacteria isolated from the same honey (and classified to the same genus, usually Bacillus spp.). This observation suggests environmental origin (nectar, water, or pollen) of the producing strains. The research carried out confirmed that honey produced in Northern Poland is a promising source of strains of bacteria producing metabolites with antimicrobial activity.

Probiotic Properties of Bacillus Strains Isolated from Stingless Bee (Heterotrigona itama) Honey Collected across Malaysia

“…Recently, the presence of B. altitudinis in stingless bee honey, H. itama, was reported for the first time [12]. B. altitudinis had been previously found in Apis mellifera honey together with other Bacillus isolates, namely B. licheniformis, B. safensis, B. zhangzhouensis, and B. xiamenensis [13]. This showed that B. altitudinis and B. pumilus have a niche in both honey samples of H. itama and A. mellifera.…”

“…Another purpose of this study was to select the bacteria that exhibited excellent antimicrobial activity against pathogenic bacteria. The successful selection of antimicrobial producers from honey has been reported by several different authors [13]. For example, Manhar et al [50] reported that B. amyloliquefaciens AMS1 inhibited the growth of L. monocytogenes and K. pneumoniae, but did not affect the growth of B. cereus, Yersinia enterocolitica, and Salmonella entericatyphimurium.…”

“…This is supported by the results from a previous study, as the presence of aerobic bacteria in honey was also detected in the range of 5.7 × 10 0 to 52.8 × 10 4 CFU/g [38]. The reason for this is that most bacteria are not able to multiply in honey due to the physicochemical properties of honey itself, such as high osmolarity, high sugar concentration, low pH, and the presence of many agents, including hydrogen peroxide and phytochemicals [13,39]. These conditions provide a stressful environment for bacteria, thus preventing the growth or even survival of different types of bacteria in honey.…”

“…Environmental factors such as nectar, water, and pollen might be responsible for the diversity of the strains. A recent study found that the highest microbial diversity was found in multifloral honey [13]. Recently, the presence of B. altitudinis in stingless bee honey, H. itama, was reported for the first time [12].…”

“…However, due to their spore-forming characteristics, which are highly stable in acidic pH, they can also colonize different environments, such as honey and various food matrices [11]. For example, Bacillus species such as B. subtilis, B. licheniformis, B. pumilus, and B. amyloliquefaciens have been detected in the fermentation of both stingless bee honey and Apis mellifera honey [12,13]. These bacteria have advantages over non-spore formers such as lactic acid bacteria (LAB) due to their heat-resistant spores [14].…”