• The Plant Pathology Journal
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• v.34 no.6
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• pp.459-469
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• 2018

Plants and microorganisms (microbes) use information from chemicals such as volatile compounds to understand their environments. Proficiency in sensing and responding to these infochemicals increases an organism's ecological competence and ability to survive in competitive environments, particularly with regard to plant-pathogen interactions. Plants and microbes acquired the ability to sense and respond to biogenic volatiles during their evolutionary history. However, these signals can only be interpreted by humans through the use of state-of the-art technologies. Newly-developed tools allow microbe-induced plant volatiles to be detected in a rapid, precise, and non-invasive manner to diagnose plant diseases. Beside disease diagnosis, volatile compounds may also be valuable in improving crop productivity in sustainable agriculture. Bacterial volatile compounds (BVCs) have potential for use as a novel plant growth stimulant or as improver of fertilizer efficiency. BVCs can also elicit plant innate immunity against insect pests and microbial pathogens. Research is needed to expand our knowledge of BVCs and to produce BVC-based formulations that can be used practically in the field. Formulation possibilities include encapsulation and sol-gel matrices, which can be used in attract and kill formulations, chemigation, and seed priming. Exploitation of biogenic volatiles will facilitate the development of smart integrated plant management systems for disease control and productivity improvement.

• The Plant Pathology Journal
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• v.21 no.1
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• pp.7-12
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• 2005

Plant growth-promoting rhizobacteria (PGPR) are a wide range of root-colonizing bacteria with the capacity to enhance plant growth and control plant pathogens. Here we review recent progress that indicate some PGPR strains release a blend of volatile organic compounds (VOCs) that promote growth in Arabidopsis seedlings and induce resistance against Erwinia carotovora subsp. carotovora. In particular, the volatile components 2,3-butanediol and acetoin released exclusively from the PGPR strains triggered the greatest level of growth promotion and induced systemic resistance. Pharmacological applications of 2,3-butanediol promoted the plant growth and induced resistance, while bacterial mutants blocked in 2,3-butanediol and acetoin synthesis was devoid of growth-promotion and induced resistance capacities. The results suggested that the bacterial VOCs play a critical role in the plant growth promotion and induced resistance by PGPR. Using transgenic and mutant lines of Arabidopsis, we provide evidences that the signal pathway activated by volatiles from one PGPR strain is dependent on cyto-kinin activation for growth promotion and dependent on an ethylene-signaling pathway for induced pathogen resistance. This discovery provides new insight into the role of bacterial VOCs as initiators of both plant growth promotion and defense responses in plants.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.9
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• pp.1362-1370
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• 2015

This study was performed to investigate the effect of different levels of dietary crude protein (CP) on composition of odorous compounds and bacterial communities in pig manure. A total of 48 male pigs (average initial body weight 45 kg) fed diets containing three levels of dietary CP (20%, 17.5%, and 15%) and their slurry samples were collected from the pits under the floor every week for one month. Changes in composition of odorous compounds and bacterial communities were analyzed by gas chromatography and 454 FLX titanium pyrosequencing systems, respectively. Levels of phenols, indoles, short chain fatty acid and branched chain fatty acid were lowest (p<0.05) in CP 15% group among three CP levels. Relative abundance of Bacteroidetes phylum and bacterial genera including Leuconostoc, Bacillus, Atopostipes, Peptonphilus, Ruminococcaceae_uc, Bacteroides, and Pseudomonas was lower (p<0.05) in CP 15% than in CP 20% group. There was a positive correlation (p<0.05) between odorous compounds and bacterial genera: phenol, indole, iso-butyric acid, and iso-valeric acid with Atopostipes, p-cresol and skatole with Bacteroides, acetic acid and butyric acid with AM982595_g of Porphyromonadaceae family, and propionic acid with Tissierella. Taken together, administration of 15% CP showed less production of odorous compounds than 20% CP group and this result might be associated with the changes in bacterial communities especially whose roles in protein metabolism.

• Food Science of Animal Resources
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• v.34 no.5
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• pp.638-646
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• 2014

The effects of two levels (1.4 vs 2.8%) of fresh garlic on lipid oxidation and microbial growth in pork patties were evaluated. Hunter color (L, a, b), pH, thiobarbituric acid reactive substances (TBARS), oxidative volatile compounds, total bacteria and Enterobacteriaceae in the pork patties with or without fresh garlic were measured during storage at $4^{\circ}C$. Addition of fresh garlic decreased redness (a), while increased pH and yellowness (b) values of the fresh pork patties were observed, regardless of the levels added. The TBARS values of the pork patties were increased with the addition of fresh garlic (p<0.05). Similar results were observed in oxidative volatile compounds. A total of 13 volatile compounds were detected in the patties (5 sulfur-containing compounds, including allyl mercaptan, allyl methyl sulfide, diallyl sulfide, methyl-(E)-propenyl-disulfide, and diallyl disulfide, and the 8 other oxidative compounds, including 1-pentanol, hexanal, 1-hexanol, heptanal, (E)-2-heptenal, 1-octen-3-ol, (E)-2-octenal and nonanal). Fresh garlic accelerated development of oxidative products in the pork patties, especially hexanal and the total oxidative volatile compounds. However, the addition of 1.4 and 2.8% of fresh garlic inhibited the growth of total bacteria and Enterobacteriaceae, indicating low total bacterial counts and Enterobacteriaceae than the controls.

• Horticultural Science & Technology
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• v.32 no.4
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• pp.558-570
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• 2014

This study was conducted to compare the volatile flavor compounds found in the leaves of 15 taxa of Korean native Chrysanthemum species. The volatile flavor compounds from the taxa were collected using a simultaneous steam distillation and extraction technique and were analyzed using gas chromatography/mass selective detector (GC/MSD). A total of 45 volatile flavor compounds were identified with six functional groups: 14 alcohols, 4 ketones, 19 hydrocarbons, 5 esters, 2 acids, and 1 aldehyde. The main functional group in 15 taxa of Chrysanthemum species was alcohols, accounting for 28.7% of volatile flavor compounds, followed by ketones (21.2%) and hydrocarbons (13.2%). Camphor, which is known for its antimicrobial properties, was the most abundant volatile compound (30%) in C. zawadskii ssp. latilobum and var. leiophyllum. In particular, C. indicum subspecies and C. boreale contained ${\alpha}$-thujone, which has outstanding anti-bacterial, anti-cancer, anti-inflammatory, anti-ulcer, and anti-diabetic efficacies. C. indicum var. albescens could be used in perfumes, since it showed 21 times more camphene than C. indicum. In addition, C. indicum var. acuta contained a fairly high content of 1,8-cineole, which has an inhibitory effect on mutagenesis. C. lineare contained only pentadecanoic acid compounds, whereas other taxa hexadecanoic acids. Overall, the Korean native Chrysanthemum species had considerable variation in volatile flavor compounds in their leaves. This study provides a good indication of specific potential use for various applications.

• The Plant Pathology Journal
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• v.38 no.2
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• pp.115-130
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• 2022

Though information exists regarding the pathogenesis of the shot-hole disease (SH) in flowering cherry (FC), there has been a lack of research focusing on SH management. Therefore, here, we investigated the inhibitory activities of antagonistic bacteria against SH pathogens both in vitro and in vivo as well as their biochemical characteristics and bioactive compounds. Two biosurfactant-producing bacterial antagonists, identified as Bacillus velezensis strains JCK-1618 and JCK-1696, exhibited the best effects against the growth of both bacterial and fungal SH pathogens in vitro through their cell-free culture filtrates (CFCFs). These two strains also strongly inhibited the growth of the pathogens via the action of their antimicrobial diffusible compounds and antimicrobial volatile organic compounds (VOCs). Crude enzymes, solvent extracts, and biosurfactants of the two strains exhibited antimicrobial activities. Liquid chromatography/electrospray ionization time-of-flight mass spectrometric analysis of the partially purified active fractions revealed that the two antagonists produced three cyclic lipopeptides, including iturin A, fengycin A, and surfactin, and a polyketide, oxydifficidin. In a detached leaf assay, pre-treatment and co-treatment of FC leaves with the CFCFs led to a large reduction in the severity of the leaf spots caused by Epicoccum tobaicum and Bukholderia contaminans, respectively. In addition, the two antagonists produced indole-3-acetic acid, siderophore, and a series of hydrolytic enzymes, along with the formation of a substantial biofilm. To our knowledge, this is the first report of the antimicrobial activities of the diffusible compounds and VOCs of B. velezensis against the SH pathogens and their efficiency in the biocontrol of SH.

• Molecules and Cells
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• v.45 no.7
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• pp.502-511
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• 2022

Bacterial volatile compounds (BVCs) exert beneficial effects on plant protection both directly and indirectly. Although BVCs have been detected in vitro, their detection in situ remains challenging. The purpose of this study was to investigate the possibility of BVCs detection under in situ condition and estimate the potentials of in situ BVC to plants at below detection limit. We developed a method for detecting BVCs released by the soil bacteria Bacillus velezensis strain GB03 and Streptomyces griseus strain S4-7 in situ using solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS). Additionally, we evaluated the BVC detection limit in the rhizosphere and induction of systemic immune response in tomato plants grown in the greenhouse. Two signature BVCs, 2-nonanone and caryolan-1-ol, of GB03 and S4-7 respectively were successfully detected using the soil-vial system. However, these BVCs could not be detected in the rhizosphere pretreated with strains GB03 and S4-7. The detection limit of 2-nonanone in the tomato rhizosphere was 1 µM. Unexpectedly, drench application of 2-nonanone at 10 nM concentration, which is below its detection limit, protected tomato seedlings against Pseudomonas syringae pv. tomato. Our finding highlights that BVCs, including 2-nonanone, released by a soil bacterium are functional even when present at a concentration below the detection limit of SPME-GC-MS.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.678-683
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• 2007

We isolated a toluene-degrading bacterium, TDB-4, from a bioreactor which designed to remove volatile organic compounds (VOCs) from the contaminated air. Based on the results of 16S rRNA gene analysis, it was classified as Pseudomonas sp. The toluene degradability was estimated in the variable toluene and bacterial concentrations. The bacterial growth and degradation rate was higher in the samples supplied with 50 ${\mu}mole/vial$ of toluene than with 10 ${\mu}mole/vial$. It was decreased, however, in the samples with 100 ${\mu}mole/vial$, indicating that toluene inhibit the growth or degradation activity of TDB-4 at high concentration. When the degradation ability of other compounds was examined, TDB-4 can degrade other VOCs such as styrene, benzene, and xylene. These results will be helpful to optimize the operating conditions to improve the efficiency of a bioreactor in detoxification of VOCs.

• Research in Plant Disease
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• v.28 no.1
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• pp.1-18
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• 2022

Volatiles exist ubiquitously in nature. Volatile compounds produced by plants and microorganisms confer inter-kingdom and intra-kingdom communications. Autoinducer signaling molecules from contact-based chemical communication, such as bacterial quorum sensing, are relayed through short distances. By contrast, biogenic volatiles derived from plant-microbe interactions generate long-distance (>20 cm) alarm signals for sensing harmful microorganisms. In this review, we discuss prior work on volatile compound-mediated diagnosis of plant diseases, and the use of volatile packaging and dispensing approaches for the biological control of fungi, bacteria, and viruses. In this regard, recent developments on technologies to analyze and detect microbial volatile compounds are introduced. Furthermore, we survey the chemical encapsulation, slow-release, and bio-nano techniques for volatile formulation and delivery that are expected to overcome limitations in the application of biogenic volatiles to modern agriculture. Collectively, technological advances in volatile compound detection, packaging, and delivery provide great potential for the implementation of ecologically-sound plant disease management strategies. We hope that this review will help farmers and young scientists understand the nature of microbial volatile compounds, and shift paradigms on disease diagnosis and management to aromatic (volatile-based) agriculture.

• Journal of Microbiology and Biotechnology
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• v.26 no.4
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• pp.648-658
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• 2016

Preservation of fresh algae plays an important role in algae seed subculture and aquaculture. The determination and examination of the changes of cell viability, composition, and bacterial species during storage would help to take suitable preservation methods to prolong the preservation time of fresh algae. Nostoc flagelliforme is a kind of edible cyanobacterium with important herbal and dietary values. This article investigated the changes of bacterial species and biochemical characteristics of fresh N. flagelliforme concentrate during natural storage. It was found that the viability of cells decreased along with the storage time. Fourteen bacteria strains in the algae concentrate were identified by PCR-DGGE and were grouped into four phyla, including Cyanobacteria, Firmicutes, Proteobacteria, and Bacteroidetes. Among them, Enterococcus viikkiensis may be a concern in the preservation. Eleven volatile organic compounds were identified from N. flagelliforme cells, in which geosmin could be treated as an indicator of the freshness of N. flagelliforme. The occurrence of indole compound may be an indicator of the degradation of cells.