scholarly journals Artificial Phylloplanes Resembling Physicochemical Characteristics of Selected Fresh Produce and Their Use in Bacteria Attachment/Removal Studies

2021 ◽  
Author(s):  
Sindy Palma-Salgado ◽  
Kang-Mo Ku ◽  
John A. Juvik ◽  
Thanh H. Nguyen ◽  
Hao Feng
Keyword(s):  
Fresh Produce ◽  
Physicochemical Characteristics ◽  
Surface Hydrophobicity ◽  
Epicuticular Wax ◽  
Ionic Surfactant ◽  
Human Pathogens ◽  
Hydrophilic Lipophilic Balance ◽  
Leaf Surfaces ◽  
Safety Interventions ◽  
Natural Leaf

Abstract The recurrence of food-borne illness outbreaks caused by consumption of fresh produce highlights the importance of developing a good understanding of the bacteria-leaf-surfaces interactions. In this study, we proposed and developed a new method to fabricate artificial phylloplanes that mimic the topographical and epicuticular characteristics of fresh produce, to be used as a platform for the development of food safety interventions for fresh produce. Romaine lettuce and spinach were selected to create phylloplane replicas using a double-cast procedure. The surface hydrophobicity of the artificial phylloplanes made from polydimethylsiloxane (PDMS) was modified by adding a non-ionic surfactant with different hydrophilic-lipophilic balance (HLB) values to match the hydrophobicity of produce leaves. Key epicuticular wax compounds identified from the natural spinach and lettuce leaves were coated on the leaf replica to mimic the chemical composition of natural leaf surfaces. These surrogate surfaces were used to study the attachment Escherichia coli O157:H7 and Listeria innocua. In addition, these surfaces are reusable, and have surface hydrophobicity, surface roughness values and epicuticular wax compositions similar to fresh produce. The artificial phylloplanes of fresh produce can be used as a platform for studying the interactions between human pathogens with produce surfaces and for developing new sanitation strategies.

scholarly journals Surfactant-induced enhancement of droplet adhesion in superhydrophobic soybean (Glycine max L.) leaves

2017 ◽  
Vol 8 ◽  
pp. 2345-2356 ◽  
Author(s):  
Oliver Hagedorn ◽  
Ingo Fleute-Schlachter ◽  
Hans Georg Mainx ◽  
Viktoria Zeisler-Diehl ◽  
Kerstin Koch
Keyword(s):  
Glycine Max ◽  
Leaf Surface ◽  
Pure Water ◽  
Epicuticular Wax ◽  
Hierarchical Organization ◽  
Water Contact ◽  
Hydrophilic Lipophilic Balance ◽  
Leaf Surfaces ◽  
Before And After ◽  
Soybean Leaf

This study performed with soybean (Glycine max L.), one of the most important crops for human and animal nutrition, demonstrates that changes in the leaf surface structure can increase the adhesion of applied droplets, even on superhydrophobic leaves, to reduce undesirable soil contamination by roll-off of agrochemical formulations from the plant surfaces. The wettability and morphology of soybean (Glycine max L.) leaf surfaces before and after treatment with six different surfactants (Agnique® SBO10 and five variations of nonionic surfactants) have been investigated. The leaf surface structures show a hierarchical organization, built up by convex epidermal cells (microstructure) and superimposed epicuticular platelet-shaped wax crystals (micro- to nanostructure). Chemical analysis of the epicuticular wax showed that 1-triacontanol (C30H61OH) is the main wax component of the soybean leaf surfaces. A water contact angle (CA) of 162.4° (σ = 3.6°) and tilting angle (TA) of 20.9° (σ = 10.0°) were found. Adherence of pure water droplets on the superhydrophobic leaves is supported by the hydrophilic hairs on the leaves. Agnique® SBO10 and the nonionic surfactant XP ED 75 increased the droplet adhesion and caused an increase of the TA from 20.9° to 85° and 90°, respectively. Scanning electron microscopy showed that surfactants with a hydrophilic–lipophilic balance value below 10 caused a size reduction of the epicuticular wax structures and a change from Cassie–Baxter wetting to an intermediate wetting regime with an increase of droplet adhesion.

scholarly journals Inhibition of Escherichia coli O157:H7 and Salmonella enterica Isolates on Spinach Leaf Surfaces Using Eugenol-Loaded Surfactant Micelles

Foods ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 575
Author(s):  
Songsirin Ruengvisesh ◽  
Chris R. Kerth ◽  
T. Matthew Taylor
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Limit Of Detection ◽  
Sodium Dodecyl ◽  
Microbial Pathogens ◽  
Escherichia Coli O157 ◽  
Human Pathogens ◽  
Surfactant Micelles ◽  
Leaf Surfaces ◽  
Spinach Leaf

Spinach and other leafy green vegetables have been linked to foodborne disease outbreaks of Escherichia coli O157:H7 and Salmonella enterica around the globe. In this study, the antimicrobial activities of surfactant micelles formed from the anionic surfactant sodium dodecyl sulfate (SDS), SDS micelle-loaded eugenol (1.0% eugenol), 1.0% free eugenol, 200 ppm free chlorine, and sterile water were tested against the human pathogens E. coli O157:H7 and Salmonella Saintpaul, and naturally occurring microorganisms, on spinach leaf surfaces during storage at 5 °C over 10 days. Spinach samples were immersed in antimicrobial treatment solution for 2.0 min at 25 °C, after which treatment solutions were drained off and samples were either subjected to analysis or prepared for refrigerated storage. Whereas empty SDS micelles produced moderate reductions in counts of both pathogens (2.1–3.2 log10 CFU/cm2), free and micelle-entrapped eugenol treatments reduced pathogens by >5.0 log10 CFU/cm2 to below the limit of detection (<0.5 log10 CFU/cm2). Micelle-loaded eugenol produced the greatest numerical reductions in naturally contaminating aerobic bacteria, Enterobacteriaceae, and fungi, though these reductions did not differ statistically from reductions achieved by un-encapsulated eugenol and 200 ppm chlorine. Micelles-loaded eugenol could be used as a novel antimicrobial technology to decontaminate fresh spinach from microbial pathogens.

scholarly journals Curing Behavior of Waterborne Paint Containing Catalyst Encapsulated in Micelle

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 375
Author(s):  
Shuji Yomo
Keyword(s):  
Storage Stability ◽  
Catalytic Properties ◽  
Ionic Surfactant ◽  
Curing Behavior ◽  
Catalytic Function ◽  
Hydrophilic Lipophilic Balance ◽  
Pot Life

This research has studied the feasibility of fabricating a catalyst that activates at 80 °C to ensure the curing performance of two-pack isocyanate curable paints, while remaining inactive at 40 °C to ensure storage stability and pot life. The research examined whether the added dibutyl tin dilaurate (DBTL) provided a catalytic function for curing the waterborne paint, which remains almost inactive at 40 °C and activates at 80 °C or higher. It was confirmed that the use of a non-ionic surfactant with a hydrophilic-lipophilic-balance (HLB) of between 13 and 14 resulted in rapid curing at a temperature of 80 °C or higher, thereby demonstrating catalytic properties. The results also show that the viscosity of the paint remained virtually unchanged after exposure for 1 h at 40 °C. This wass presumed to be the result of the DBTL, which was constrained by the micelles up to a temperature of 70 °C, breaking down the micelles at a temperature of 80 °C or higher. It was also confirmed that the catalytic switching properties were not obtained at a lower or higher HLB. It was found that selecting the non-ionic surfactant by HLB can control the activating temperature of the catalytic properties.

Analysis of Native Microflora and Selection of Strains Antagonistic to Human Pathogens on Fresh Produce†

2001 ◽  
Vol 64 (8) ◽  
pp. 1110-1115 ◽  
Author(s):  
CHING-HSING LIAO ◽  
WILLIAM F. FETT
Keyword(s):  
Fresh Produce ◽  
Brain Heart Infusion ◽  
Erwinia Carotovora ◽  
Plate Count ◽  
Human Pathogens ◽  
Green Pepper ◽  
Significant Difference ◽  
Bell Peppers ◽  
Native Microflora ◽  
Baby Carrots

The native microflora of three types of produce (green bell peppers, Romaine lettuce, and prepeeled baby carrots) and two types of sprouting seeds (alfalfa and clover) were investigated. Aerobic plate count (APC) for each produce or seed type as determined on Pseudomonas agar F (PAF) with incubation at 28°C was in the range of 4 to 7 log CFU per g of tissue or seed. There was no significant difference (P ≥ 0.05) in APC when the determinations were made with three agar media including PAF, brain heart infusion agar, and plate count agar. However, the APC as determined from plates that were incubated at 28°C was significantly (P ≤ 0.05) higher than with incubation at 37°C. Fluorescent pseudomonads accounted for 23 to 73% of APC and 6 to 18% of APC recovered from carrots, pepper, and lettuce were pectolytic. Forty-eight strains of pectolytic bacteria were randomly isolated and identified, respectively, as members of the genera of Pseudomonas, Erwinia, Bacillus, Xanthomonas, or Flavobacterium. Lactic acid bacteria and/or yeast were consistently isolated from baby carrots, lettuce, and sprouting seeds (alfalfa or clover) but not from green bell peppers. Approximately 120 strains of indigenous microflora were tested for their ability to inhibit the growth of Salmonella Chester, Listeria monocytogenes, Escherichia coli, or Erwinia carotovora subsp. carotovora on PAF. Six isolates capable of inhibiting the growth of at least one pathogen were isolated and identified, respectively, as Bacillus spp. (three strains), Pseudomonas aeruginosa (one strain), Pseudomonas fluorescens (strain A3), and yeast (strain D1). When green pepper disks were inoculated with strains A3 and D1, the growth of Salmonella Chester and L. monocytogenes on the disks was reduced by 1 and 2 logs, respectively, over a period of 3 days. Application of strains A3 and D1 as potential biopreservatives for enhancing the quality and safety of fresh produce is discussed.

A study on cell surface hydrophobicity, growth and metabolism of Zymomonas mobilis influenced by PEG as a pretreatment agent

RSC Advances ◽  
2015 ◽  
Vol 5 (60) ◽  
pp. 48176-48180
Author(s):  
Niloofar Nasirpour ◽  
Seyyed Mohammad Mousavi ◽  
Seyed Abbas Shojaosadati
Keyword(s):  
Polyethylene Glycol ◽  
Cell Surface ◽  
Zymomonas Mobilis ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Ionic Surfactant ◽  
Peg 4000

This study investigates the effects of polyethylene glycol (PEG) 4000, a non-ionic surfactant, on the cell surface hydrophobicity (CSH) ofZymomonas mobilis, as well as its growth and metabolism.

scholarly journals Good and bad lettuce leaf microbes? Unravelling the genetic architecture of the microbiome to inform plant breeding for enhanced food safety and reduced food waste

2021 ◽  
Author(s):  
Annabelle Damerum ◽  
Elizabeth C Arnold ◽  
Villo Bernad ◽  
Hazel K Smith ◽  
Gail Taylor
Keyword(s):  
Bacterial Diversity ◽  
Food Waste ◽  
Genetic Architecture ◽  
Leaf Surface ◽  
Surface Characteristics ◽  
Surface Hydrophobicity ◽  
Human Pathogens ◽  
Host Genotype ◽  
Spoilage Bacteria ◽  
Bacterial Microbiome

Lettuce is a high value food crop, consumed raw around the world. Engineering of the leaf microbiome could provide significant benefits for enhanced crop yield and stress resistance and help to reduce food waste caused by microbial spoilage. Lettuce leaves also act as a vector for human pathogens, implicated in several high-profile food-borne disease outbreaks. Since host genotype helps determine microbiome composition, we hypothesize that leaf surface traits can be defined that associate with "good" bacterial microbiomes providing benefits to the crop and that "bad" microbiomes, where spoilage organisms and human pathogens are abundant, can also be associated to underlying leaf genetics, providing key targets for future crop breeding. Using a Recombinant Inbred Line (RIL) population, we show that cultivated and wild parental genotypes differ with reduced bacterial diversity, larger leaves and fewer, larger stomata, smaller epidermal cells and more hydrophilic leaf surfaces found in the cultivated compared to wild lettuce. Functional analysis of the associated microbiome revealed increased abundance of genes associated with disease virulence for the cultivated lettuce genotype, suggesting domestication has had broad impacts on leaf and associated bacterial microbiome traits. We defined the core lettuce bacterial microbiome from 171 RILs, comprised of 45 taxa in the phyla Proteobacteria, Actinobacteria, Firmicutes, Chloroflexi and Deinococcus-Thermus. Leaf surface characteristics important in influencing bacterial diversity and abundance were identified as stomatal size (length and width), epidermal cell area and number and leaf surface hydrophobicity of the abaxial leaf surface. Quantitative trait loci (QTL) for leaf surface traits, frequently mapped alongside those for the extended phenotype of bacterial taxa abundance, including for human pathogens Campylobacter spp., Escherichia-Shigella spp., Clostridium spp. (LG 4, 5 and 6) and spoilage bacteria, Pseudomonas spp. (LG 1, 3, 4, 6 and 9). Candidate genes underlying these QTL were enriched in GO terms for cell wall assembly and modification, defence response, hormone-mediated signalling and biosynthesis and anatomical structure development. This work provides the first insight into the genetic architecture of host surface traits in a leafy crop alongside the mapped genetic architecture of bacterial communities and has identified areas of the lettuce genome as important targets for future microbiome engineering.

scholarly journals Differential Survivability of Two Genetically Similar Salmonella Thompson Strains on Pre-harvest Sweet Basil (Ocimum basilicum) Leaves

2021 ◽  
Vol 12 ◽  
Author(s):  
Ye Htut Zwe ◽  
Michelle Mei Zhen Ten ◽  
Xinyi Pang ◽  
Chun Hong Wong ◽  
Dan Li
Keyword(s):  
Gene Expression ◽  
Fresh Produce ◽  
Ocimum Basilicum ◽  
Survival Strategies ◽  
Post Inoculation ◽  
Human Pathogens ◽  
Adaxial Surface ◽  
Macroscopic Lesion ◽  
Better Than ◽  
Expression Polymorphism

Although conventionally considered an animal pathogen, recent evidence increasingly suggests that fresh produce may act as significant transmission vehicles and alternative hosts to Salmonella. This study reports the differential survivability of two genetically similar Salmonella Thompson strains (ST 889B and ST 688C) on the adaxial surface of pre-harvest basil (Ocimum basilicum) leaves. Upon inoculation, two distinct phenomena, a dried water-print or a macroscopic lesion, were observed within 24 h. ST 889B survived better than ST 688C on healthy-looking leaves without lesions, possibly due to its higher biofilm-forming ability. Both strains survived better on the leaves with lesions than on the healthy-looking leaves (ST 688C: 4.39 ± 0.68 vs. 2.18 ± 0.29; ST 889B: 4.78 ± 0.12 vs. 2.83 ± 0.18 log CFU per sample at 6 days post-inoculation). ST 889B caused the formation of lesions at a higher frequency [70/117 leaves (59.8%)] than ST 688C [35/96 leaves (36.5%)]. Thus, we highlighted two distinct Salmonella survival strategies in the basil pathosystem and demonstrated gene expression polymorphism (variations in the expression of the same set of genes) as an indispensable strategy in the colonization of plants as hosts by the human pathogens.

Bacterial Communities Associated with Retail Alfalfa Sprouts

2008 ◽  
Vol 71 (1) ◽  
pp. 200-204 ◽  
Author(s):  
CINDY LOUI ◽  
GRIGOR GRIGORYAN ◽  
HAOHAO HUANG ◽  
LEE W. RILEY ◽  
SANGWEI LU
Keyword(s):  
Bacterial Community ◽  
Bacterial Communities ◽  
Fresh Produce ◽  
Growth Conditions ◽  
Human Pathogens ◽  
Culture Independent ◽  
Foodborne Outbreaks ◽  
Total Bacterial Community ◽  
Alfalfa Sprouts ◽  
Alfalfa Sprout

Fresh produce, including salad, is increasingly implicated in foodborne outbreaks. Although studies have been carried out to detect specific human pathogens from fresh produce, the total bacterial community associated with fresh produce is poorly understood. In this study, we characterized the bacterial community associated with alfalfa sprouts, using a culture-independent method. Four retail-purchased alfalfa sprout samples were obtained from different producers, and the bacterial community associated with each sample was determined by 16S rDNA profiling. Our results indicate that alfalfa sprouts sampled in our study shared significant similarities in their bacterial communities. Proteobacteria was the dominant phylum detected from all alfalfa sprout samples, with Enterobacteriaceae, Oxalobacteraceae, Moraxellaceae, and Sphingomonadaceae as the most frequently detected families. These results indicate that growth conditions of alfalfa sprouts should be taken into consideration to prevent the proliferation of pathogenic proteobacteria such as Escherichia coli O157 and Salmonella.

scholarly journals Deciphering the microbiome shift during fermentation of medicinal plants

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Martina Köberl ◽  
Sabine Erschen ◽  
Mohammad Etemadi ◽  
Richard Allen White ◽  
Tarek F. El-Arabi ◽  
...  
Keyword(s):  
Medicinal Plants ◽  
Time Course ◽  
Human Microbiome ◽  
Fermented Food ◽  
Gene Profiling ◽  
Rrna Gene ◽  
Positive Health ◽  
Leaf Surfaces ◽  
Natural Leaf ◽  
Positive Health Outcomes

Abstract The importance of the human-microbiome relationship for positive health outcomes has become more apparent over the last decade. Influencing the gut microbiome via modification of diet represents a possibility of maintaining a healthy gut flora. Fermented food and lactic acid bacteria (LAB) display a preventive way to inhibit microbial dysbioses and diseases, but their ecology on plants is poorly understood. We characterized the microbiome of medicinal plants (Matricaria chamomilla L. and Calendula officinalis L.) using 16S rRNA gene profiling from leaves that were fermented over a six-week time course. The unfermented samples were characterized by a distinct phyllosphere microbiome, while the endosphere revealed a high similarity. During fermentation, significant microbial shifts were observed, whereby LAB were enhanced in all approaches but never numerically dominated. Among the LAB, Enterococcaceae were identified as the most dominant family in both plants. M. chamomilla community had higher relative abundances of Lactobacillaceae and Carnobacteriaceae, while C. officinalis showed a higher presence of Leuconostocaceae and Streptococcaceae. The natural leaf microbiome and the indigenous LAB communities of field-grown Asteraceae medicinal plants are plant-specific and habitat-specific and are subjected to significant shifts during fermentation. Leaf surfaces as well as leaf endospheres were identified as sources for biopreservative LAB.

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