Seed-borne bacterial synthetic community resists seed pathogenic fungi and promotes plant growthLuo, De-Lin; Huang, Shi-Yi; Ma, Chen-Yu; Zhang, Xiang-Yu; Sun, Kai; Zhang, Wei; Dai, Chuan-Chao
doi: 10.1093/jambio/lxae073pmid: 38520150
AimsIn this study, the control effects of synthetic microbial communities composed of peanut seed bacteria against seed aflatoxin contamination caused by Aspergillus flavus and root rot by Fusarium oxysporum were evaluated.Methods and resultsPotentially conserved microbial synthetic communities (C), growth-promoting synthetic communities (S), and combined synthetic communities (CS) of peanut seeds were constructed after 16S rRNA Illumina sequencing, strain isolation, and measurement of plant growth promotion indicators. Three synthetic communities showed resistance to root rot and CS had the best effect after inoculating into peanut seedlings. This was achieved by increased defense enzyme activity and activated salicylic acid (SA)-related, systematically induced resistance in peanuts. In addition, CS also inhibited the reproduction of A. flavus on peanut seeds and the production of aflatoxin. These effects are related to bacterial degradation of toxins and destruction of mycelia.ConclusionsInoculation with a synthetic community composed of seed bacteria can help host peanuts resist the invasion of seeds by A. flavus and seedlings by F. oxysporum and promote the growth of peanut seedlings.
Reviewing the evidence of antimicrobial activity of glycolsDuggan, Katrina; Ijaz, M Khalid; McKinney, Julie; Maillard, Jean-Yves
doi: 10.1093/jambio/lxae071pmid: 38573833
In the 1940s and 1950s, researchers seeking safe and novel ways to eliminate airborne pathogens from enclosed spaces, investigated glycol vapours as a method of disinfection. More recently, the COVID-19 pandemic highlighted the need for a non-toxic aerial disinfectant that can be used in the presence of people. This scoping review is intended to analyse the early and more recent literature on glycol disinfection, scrutinizing the methodologies used, and to determine if the use of glycols as modern-day disinfectants is justifiedPRISMA-ScR guidelines were used to assess the 749 articles retrieved from the Web of Science platform, with 46 articles retained after the search strategy was applied. Early studies generally demonstrated good disinfection capabilities against airborne bacteria and viruses, particularly with propylene glycol (PG) vapour. Vapour pressure, relative humidity, and glycol concentration were found to be important factors affecting the efficacy of glycol vapours. Contact times depended mainly on the glycol application method (i.e. aerosolization or liquid formulation), although information on how glycol efficacy is impacted by contact time is limited. Triethylene glycol (TEG) is deemed to have low toxicity, carcinogenicity, and mutagenicity and is registered for use in air sanitization and deodorization by the US Environmental Protection Agency. Glycols are also used in liquid formulations for their antimicrobial activity against a wide range of microorganisms, although when used as a non-active excipient in products, their contribution to antimicrobial efficacy is rarely assessed. The appropriate use of liquid glycol-containing formulations was found to positively impact the antimicrobial capabilities of disinfectants when used at temperatures <0, food preservatives, and dental medicaments. Providing modern delivery technology can accurately control environmental conditions, the use of aerosolized glycol formulations should lead to successful disinfection, aiding infection prevention, and control regimens.
Microbiological quality of irrigation water on highly diverse fresh produce smallholder farms: elucidating environmental routes of contaminationViviers, Sheldon A; Richter, Loandi; du Plessis, Erika M; Korsten, Lise
doi: 10.1093/jambio/lxae091pmid: 38632044
AimTo evaluate the microbiological safety, potential multidrug-resistant bacterial presence and genetic relatedness (DNA fingerprints) of Escherichia coli isolated from the water-soil-plant nexus on highly diverse fresh produce smallholder farms.Methods and resultsIrrigation water (n = 44), soil (n = 85), and fresh produce (n = 95) samples from six smallholder farms with different production systems were analysed for hygiene indicator bacterial counts and the presence of shigatoxigenic E. coli and Salmonella spp. using standard microbiological methods. Identities of isolates were confirmed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), and the genetic relatedness of the E. coli isolates determined using enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) analysis. Irrigation water E. coli levels ranged between 0 and 3.45 log MPN/100 ml−1 with five farms having acceptable levels according to the World Health Organization limit (3 log MPN/100 ml−1). Fresh produce samples on four farms (n = 65) harboured E. coli at low levels (<1 log CFU/g−1) except for one sample from kale, spring onion, green pepper, onion, and two tomato samples, which exceeded international acceptable limits (100 CFU/g−1). Only one baby carrot fresh produce sample tested positive for Salmonella spp. Of the 224 samples, E. coli isolates were identified in 40% (n = 90) of all water, soil, and fresh produce types after enrichment. Additionally, the DNA fingerprints of E. coli isolates from the water-soil-plant nexus of each respective farm clustered together at high similarity values (>90%), with all phenotypically characterized as multidrug-resistant.ConclusionsThe clustering of E. coli isolated throughout the water-soil-plant nexus, implicated irrigation water in fresh produce contamination. Highlighting the importance of complying with irrigation water microbiological quality guidelines to limit the spread of potential foodborne pathogens throughout the fresh produce supply chain.
Isolation and genome characterization of Paenibacillus polymyxa 188, a potential biocontrol agent against fungiShih, Sra-Yh; Huang, You-Syu; Chou, Ker-Rui; Wu, Hung-Yi; Tsai, HsinYuan
doi: 10.1093/jambio/lxae075pmid: 38509027
AimsIn this work, we aimed to isolate marine bacteria that produce metabolites with antifungal properties.Methods and resultsPaenibacillus polymyxa 188 was isolated from a marine sediment sample, and it showed excellent antifungal activity against many fungi pathogenic to plants (Fusarium tricinctum, Pestalotiopsis clavispora, Fusarium oxysporum, F. oxysporum f. sp. Cubense (Foc), Curvularia plantarum, and Talaromyces pinophilus) and to humans (Aspergillus terreus, Penicillium oxalicum, and Microsphaeropsis arundinis). The antifungal compounds produced by P. polymyxa 188 were extracted and analyzed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The complete genome sequence and biosynthetic gene clusters of P. polymyxa 188 were characterized and compared with those of other strains. A total of 238 carbohydrate-active enzymes (CAZymes) were identified in P. polymyxa 188. Two antibiotic gene clusters, fusaricidin and tridecaptin, exist in P. polymyxa 188, which is different from other strains that typically have multiple antibiotic gene clusters.ConclusionsPaenibacilluspolymyxa 188 was identified with numerous biosynthetic gene clusters, and its antifungal ability against pathogenic fungi was verified.
Nonthermal plasma air disinfection for the inactivation of airborne microorganisms in an experimental chamber and indoor airLi, Ye; Wei, Lanfen; Lin, Junming; Xie, Zhongyi; Lu, Longxi; Pan, Xieshang; Xu, Ji; Cai, Ran
doi: 10.1093/jambio/lxae078pmid: 38520159
AimsAirborne transmission of diseases presents a serious threat to human health, so effective air disinfection technology to eliminate microorganisms in indoor air is very important. This study evaluated the effectiveness of a non-thermal plasma (NTP) air disinfector in both laboratory experiments and real environments.Methods and resultsAn experimental chamber was artificially polluted with a bioaerosol containing bacteria or viruses. Additionally, classroom environments with and without people present were used in field tests. Airborne microbial and particle concentrations were quantified. A 3.0 log10 reduction in the initial load was achieved when a virus-containing aerosol was disinfected for 60 min and a bacteria-containing aerosol was disinfected for 90 min. In the field test, when no people were present in the room, NTP disinfection decreased the airborne microbial and particle concentrations (P < 0.05). When people were present in the room, their constant activity continuously contaminated the indoor air, but all airborne indicators decreased (P < 0.05) except for planktonic bacteria (P = 0.094).ConclusionsNTP effectively inactivated microorganisms and particles in indoor air.
Strain specific Starmerella bacillaris and Saccharomyces cerevisiae interactions in mixed fermentationsEnglezos, Vasileios; Di Gianvito, Paola; Serafino, Gabriele; Giacosa, Simone; Cocolin, Luca; Rantsiou, Kalliopi
doi: 10.1093/jambio/lxae085pmid: 38549426
AimsYeast interactions have a key role in the definition of the chemical profile of the wines. For this reason, winemakers are increasingly interested in mixed fermentations, employing Saccharomyces cerevisiae and non-Saccharomyces strains. However, the outcome of mixed fermentations is often contradictory because there is a great variability among strains within species. Previously, it was demonstrated that the loss of culturability of Starmerella bacillaris in mixed fermentations with S. cerevisiae was due to the physical contact between cells. Therefore, to further explore previous observations, the interaction mechanisms among different strains of Starm. bacillaris and S. cerevisiae during mixed fermentations were investigated.Methods and resultsFermentations were conducted under conditions that allow physical contact between cells (flasks) but also using a double-compartment fermentation system in which cells of both species were kept separate. The role of competition for nutrients and antimicrobial compounds production on yeast–yeast interaction mechanisms was also investigated. Three Starm. bacillaris and three S. cerevisiae strains were used to investigate if interaction mechanisms are modulated in a strain-specific way. Both species populations were affected by physical contact, particularly Starm. bacillaris that lost its culturability during fermentation. In addition, loss of culturability of Starm. bacillaris strains was observed earlier in flasks than in the double-compartment system. The phenomena observed occurred in a strain couple-dependent way. Starm. bacillaris disappearance seemed to be independent of nutrient depletion or the presence of inhibitory compounds (which were not measured in this study).ConclusionOverall, the results of the present study reveal that cell-to-cell contact plays a role in the early death of non-Saccharomyces but the extent to which it is observed depends greatly on the Starm. bacillaris/S. cerevisiae strains tested.