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American foulbrood is a dangerous disease of bee broods found worldwide, caused by the Paenibacillus larvae larvae L. bacterium. In an experiment, the possibility of detecting colonies of this bacterium on MYPGP substrates (which contains yeast extract, Mueller-Hinton broth, glucose, K2HPO4, sodium pyruvate, and agar) was tested using a prototype of a multi-sensor recorder of the MCA-8 sensor signal with a matrix of six semiconductors: TGS 823, TGS 826, TGS 832, TGS 2600, TGS 2602, and TGS 2603 from Figaro. Two twin prototypes of the MCA-8 measurement device, M1 and M2, were used in the study. Each prototype was attached to two laboratory test chambers: a wooden one and a polystyrene one. For the experiment, the strain used was P. l. larvae ATCC 9545, ERIC I. On MYPGP medium, often used for laboratory diagnosis of American foulbrood, this bacterium produces small, transparent, smooth, and shiny colonies. Gas samples from over culture media of one- and two-day-old foulbrood P. l. larvae (with no colonies visible to the naked eye) and from over culture media older than 2 days (with visible bacterial colonies) were examined. In addition, the air from empty chambers was tested. The measurement time was 20 min, including a 10-min testing exposure phase and a 10-min sensor regeneration phase. The results were analyzed in two variants: without baseline correction and with baseline correction. We tested 14 classifiers and found that a prototype of a multi-sensor recorder of the MCA-8 sensor signal was capable of detecting colonies of P. l. larvae on MYPGP substrate with a 97% efficiency and could distinguish between MYPGP substrates with 1–2 days of culture, and substrates with older cultures. The efficacy of copies of the prototypes M1 and M2 was shown to differ slightly. The weighted method with Canberra metrics (Canberra.811) and kNN with Canberra and Manhattan metrics (Canberra. 1nn and manhattan.1nn) proved to be the most effective classifiers. Full article

Paenibacillus larvae is a Gram-positive bacterium, the spores of which are the causative agent of the most destructive brood disease of honeybees, American foulbrood (AFB). Obtaining viable spores of pathogen strains is requisite for different studies concerning AFB. The aim of this work was to investigate the effects of five saccharides that may naturally occur in higher amounts in bee larvae on in vitro sporulation of P. larvae. The effect of individual saccharides at different concentrations on spore yields of P. larvae strains of epidemiologically important ERIC genotypes was examined in Columbia sheep blood agar (CSA) and MYPGP agar media. It was found that fructose in ERIC I and trehalose in ERIC II strains at concentrations in the range of 0.5–2% represent new sporulation factors that significantly enhanced the yields of viable spores in both media, mostly in a concentration-dependent manner. The enhancements in spore yield were mainly caused by improvements of the germination ability of the spores produced. Glucose, maltose and sucrose at 1% or 0.5% concentrations also supported sporulation but to a lower extent and not in all strains and media. Based on the knowledge gained, a novel procedure was proposed for the preparation of viable P. larvae spores with supposed improved quality for AFB research. Full article