Characterization of Microbial Communities Populating the Inflorescences of <i>Humulus lupulus</i> L.

Allen, Mary E.; Piefer, Andrew J.; Cole, Sean N.; Werner, Jeffrey J.; Benziger, Peter Todd; Grieneisen, Laura; Britton, Scott J.

doi:10.1080/03610470.2019.1667739

Cited by 7 publications

(8 citation statements)

References 55 publications

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“…Interestingly, it has been shown that the VBNC state may be related to antibiotic persistence of some pathogenic bacteria ( Fakruddin et al, 2013 ; Allen et al, 2019 ). The VBNC state and antibiotic persistence are both states of bacterial dormancy.…”

Section: Methods Of Bsm Detectionmentioning

confidence: 99%

Methods for detection and identification of beer-spoilage microbes

Oldham

Held

2023

Front. Microbiol.

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It is critical that breweries of all sizes routinely monitor the microbiome of their process to limit financial losses due to microbial contamination. Contamination by beer-spoiling microbes (BSMs) at any point during the brewing process may lead to significant losses for breweries if gone undetected and allowed to spread. Testing and detection of BSMs must be routine and rapid, and because even small breweries need the capability of BSM detection and identification, the method also needs to be affordable. Lactic acid bacteria (LAB) are responsible for most spoilage incidents, many of which have been shown to enter the viable but nonculturable (VBNC) state under conditions present in beer such as cold or oxidative stress. These bacteria are invisible to traditional methods of detection using selective media. This article describes several methods of BSM detection and identification that may be useful in the majority of craft breweries. While there are several genomic methods that meet some or many qualifications of being useful in craft breweries, real-time quantitative polymerase chain reaction (qPCR) currently best meets the desired method characteristics and holds the most utility in this industry, specifically SYBR Green qPCR. qPCR is a targeted method of detection and identification of microbes that is affordable, rapid, specific, sensitive, quantitative, and reliable, and when paired with valid DNA extraction techniques can be used to detect BSMs, including those in the VBNC state.

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Section: Methods Of Bsm Detectionmentioning

confidence: 99%

Methods for detection and identification of beer-spoilage microbes

Oldham

Held

2023

Front. Microbiol.

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“…A number of Fusarium species are reported to infect cannabis through a similar point of entry (Punja, 2021c), indicating the importance of stigmatic tissues in providing access to pathogens and TYM. Microbiome studies of the inflorescence tissues of cannabis should provide useful insights into the microbial communities, similar to what has been described from hop flowers (anthosphere microbiome) (Allen et al, 2019) and also in different tissue compartments within hemp plants (Barnett et al, 2020;Ahmed et al, 2021;Wei et al, 2021) and cannabis plants (Comeau et al, 2020). These studies would shed light on the temporal colonization of cannabis inflorescences as a function of genotype, environment and other factors, potentially leading to a better understanding of how TYM populations become established.…”

Section: Discussionmentioning

confidence: 67%

Total yeast and mold levels in high THC-containing cannabis (Cannabis sativa L.) inflorescences are influenced by genotype, environment, and pre-and post-harvest handling practices

Punja,

Ni,

Lung

et al. 2023

Front. Microbiol.

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Total yeast and mold (TYM) levels in inflorescences of high THC-containing Cannabis sativa (cannabis) are regulated to ensure that medicinal and recreational users, especially those with immunocompromised systems, are not exposed to potentially harmful levels. In North America, the limits imposed range from 1,000–10,000 cfu/g of dried product to 50,000–100,000 cfu/g, depending on the jurisdiction. Factors affecting a build-up of TYM in cannabis inflorescences have not been previously researched. In this study, >2,000 fresh and dried samples were assayed for TYM over a 3-year period (2019–2022) to identify specific factors which can contribute to TYM levels. Greenhouse-grown inflorescences were sampled before and after commercial harvest, homogenized for 30 s, and plated onto potato dextrose agar (PDA) with 140 mg/L streptomycin sulfate. Colony-forming-units (cfu) were rated after 5 days of incubation at 23°C under 10–14 h light. PDA provided more consistent counts of cfu compared to Sabouraud dextrose and tryptic soy agars. The predominant fungal genera identified by PCR of the ITS1-5.8S-ITS2 region of rDNA were Penicillium, Aspergillus, Cladosporium, and Fusarium. In addition, four yeast genera were recovered. In total, 21 species of fungi and yeasts constituted the total cfu present in the inflorescences. The variables that significantly (p < 0.05) increased these TYM levels in inflorescences were: the genotype (strain) grown, presence of leaf litter in the greenhouse, harvesting activity by workers, genotypes with a higher abundance of stigmatic tissues and inflorescence leaves, higher temperature and relative humidity within the inflorescence microclimate, time of year (May–October), method of drying buds after harvest, and inadequate drying of buds. The variables which significantly (p < 0.05) decreased TYM in samples were: genotypes with lower numbers of inflorescence leaves, air circulation achieved by fans during inflorescence maturation, harvesting during November–April, hang-drying of entire inflorescence stems, and drying to a moisture content of 12–14% (water activity of 0.65–0.7) or lower which was inversely correlated with cfu levels. Under these conditions, the majority of dried commercial cannabis samples contained <1,000–5,000 cfu/g. Our findings indicate that TYM in cannabis inflorescences are the result of a dynamic interaction between genotype, environment, and post-harvest handling methods. Some of these factors may be altered by cannabis producers to reduce the potential build-up of these microbes. Among the 21 fungal and yeast species recovered from greenhouse-grown cannabis inflorescences, a few could pose a potential threat to human health, while many do not and they could provide beneficial interactions within the cannabis plant. The currently recommended plating methods onto agar media and enumeration of total cfu are unable to distinguish between these two groups.

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“…The flavor of this fraction is dependent on the hop variety, and recently the cultivation of specific aromatic flavor hop cultivars has been increasing. In addition to the cultivar, the climatic conditions as well as the cultivation area and soil all influence the flavor of the oil (Allen et al 2019;Almaguer et al 2014;Bedini et al 2016;Eyres et al 2007;Holle et al, 2019;Van opstaele et al 2012).…”

Section: Hormone Replacement Therapy (Hrt)mentioning

confidence: 99%

Hop (Humulus lupulus L.): Traditional and Present Use, and Future Potential

Korpelainen

Pietiläinen

2021

Econ Bot

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Hop (Humulus lupulus L.): Traditional and Present Use, and Future Potential. Hop (Humulus lupulus) is best known for its use in beer brewing owing to its bittering flavor and floral aroma. Today, the brewing industry uses as much as 98% of the produced hop crop worldwide. However, there are many other uses, some of them known since prehistoric times. Hops, the cone–like female structures called strobili, are the most frequently used part of the hop plant, but other tissues are of interest as well. The present review compiles existing knowledge of the chemical and pharmacological properties, traditional and present uses and further use potential, genetic resources, and breeding attempts in H. lupulus, and discusses climate change challenges to hop production. It contains hundreds of phytochemicals, and some of the secondary metabolites have definite potential pharmacological and medicinal value, but further investigations are desirable. Hop substances are potential alternatives, e.g., in antimicrobial, cancer, metabolic syndrome, and hormone replacement therapy treatments, as well as insecticides, preservatives, and fragrances. There are presently a few hundred cultivated hop varieties, and new cultivars are being developed and tested. Future hop breeding efforts with different quality and adaptation targets can utilize existing genetic resources, such as wild populations and landraces present in many regions.

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Characterization of Microbial Communities Populating the Inflorescences of Humulus lupulus L.

Cited by 7 publications

References 55 publications

Methods for detection and identification of beer-spoilage microbes

Methods for detection and identification of beer-spoilage microbes

Total yeast and mold levels in high THC-containing cannabis (Cannabis sativa L.) inflorescences are influenced by genotype, environment, and pre-and post-harvest handling practices

Hop (Humulus lupulus L.): Traditional and Present Use, and Future Potential

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