Articles
Microbial community of hop (Humulus lupulus L.) and its impact on the quality of hop products
Article number
1328_15
Pages
109 – 114
Language
English
Abstract
During the growing seasons 2015-2019, the composition of the microbial community on the surface of leaves and cones of hop plants cultivated in the ‘Saaz’ hop growing area (Czech Republic) was studied.
During the growing seasons, several leaf samplings were carried out between June to September.
Cones were sampled immediately before harvesting.
All species of bacteria were identified using the microbiological ID system Biolog (Biolog, Hayward, California). The fungi were identified at the genera level, using microscopic observations and the morphological appearance of the colonies on the dishes.
In the bacterial community, Bacillus species (megatherium, idriensis, indicus, endophyticus) and Pantoea species (agglomerans, dispersa) were most frequently identified.
Fungi of the genus Talaromyces, Penicillium, Alternaria, Fusarium, and Rhizopus were regularly identified on leaves and cones surfaces.
Bacteria of Pantoea sp. have also been found in dry hops and even in hop pellets packed in barrier aluminium bags in a modified inert atmosphere.
It has been found that bacteria of the genus Pantoea can metabolize hops carbohydrates at room temperature in the absence of oxygen while releasing carbon dioxide.
This process is manifested externally by inflating and increasing the volume of bags with hop pellets.
This causes logistical problems during handling and transport.
This undesirable process can be effectively suppressed by reducing the amount of biological impurities in the harvested hops and storage of pellets in air-conditioned warehouses at temperatures up to +5°C.
During the growing seasons, several leaf samplings were carried out between June to September.
Cones were sampled immediately before harvesting.
All species of bacteria were identified using the microbiological ID system Biolog (Biolog, Hayward, California). The fungi were identified at the genera level, using microscopic observations and the morphological appearance of the colonies on the dishes.
In the bacterial community, Bacillus species (megatherium, idriensis, indicus, endophyticus) and Pantoea species (agglomerans, dispersa) were most frequently identified.
Fungi of the genus Talaromyces, Penicillium, Alternaria, Fusarium, and Rhizopus were regularly identified on leaves and cones surfaces.
Bacteria of Pantoea sp. have also been found in dry hops and even in hop pellets packed in barrier aluminium bags in a modified inert atmosphere.
It has been found that bacteria of the genus Pantoea can metabolize hops carbohydrates at room temperature in the absence of oxygen while releasing carbon dioxide.
This process is manifested externally by inflating and increasing the volume of bags with hop pellets.
This causes logistical problems during handling and transport.
This undesirable process can be effectively suppressed by reducing the amount of biological impurities in the harvested hops and storage of pellets in air-conditioned warehouses at temperatures up to +5°C.
Publication
Authors
K. Krofta, L. Mravcová, D. Kolek, P. Patáková, J. Patzak, A. Henychová, P. Dostálek
Keywords
phyllosphere, bacteria, fungi, Pantoea agglomerans, modified atmosphere
Online Articles (21)