Evaluation of steam pasteurization in controlling Salmonella serotype Enteritidis on raw almond surfaces

Aim: To investigate the efficacy of steam pasteurization for reducing Salmonella serotype Enteritidis on raw almond surfaces. Methods and Results: Nonpareil almonds were inoculated to 10^7–8 CFU g^?1 with a Salm. Enteritidis cocktail (Salm. Enteritidis 43353, ME‐13, ME‐14) or Salm. Enteritidis phage type 30, dried overnight and subjected to steam treatments through a pilot‐sized vertical pasteurization machine for 5, 15, 25, 35, 45, 55 and 65 s to investigate the effect of steam on a single layer of almond. Survival of Salm. Enteritidis was evaluated with tryptic soy agar and xylose lysine desoxycholate overlay for total and healthy cells, respectively. No significant differences (P > 0·05) in reduction were observed between the Salm. Enteritidis cocktail and Salm. Enteritidis PT 30 inoculum. Reduction of Salm. Enteritidis increased as a function of treatment time, with 25 s being sufficient to achieve a 5‐log reduction. Discolouration and visible formation of wrinkles were observed following steam pasteurization of more than 35 s. Conclusions: Steam pasteurization of 25 s is sufficient to achieve a 5‐log reduction of Salm. Enteritidis inoculated on raw almonds without visual quality degradation. Significance and Impact of the Study: Steam pasteurization is an effective alternative to reduce or prevent Salm. Enteritidis contamination on raw almonds.     

Production of high levels of poly‐3‐hydroxybutyrate in plastids of Camelina sativa seeds

Poly‐3‐hydroxybutyrate (PHB) production in plastids of Camelina sativa seeds was investigated by comparing levels of polymer produced upon transformation of plants with five different binary vectors containing combinations of five seed‐specific promoters for expression of transgenes. Genes encoding PHB biosynthetic enzymes were modified at the N‐terminus to encode a plastid targeting signal. PHB levels of up to 15% of the mature seed weight were measured in single sacrificed T₁ seeds with a genetic construct containing the oleosin and glycinin promoters. A more detailed analysis of the PHB production potential of two of the best performing binary vectors in a Camelina line bred for larger seed size yielded lines containing up to 15% polymer in mature T₂ seeds. Transmission electron microscopy showed the presence of distinct granules of PHB in the seeds. PHB production had varying effects on germination, emergence and survival of seedlings. Once true leaves formed, plants grew normally and were able to set seeds. PHB synthesis lowered the total oil but not the protein content of engineered seeds. A change in the oil fatty acid profile was also observed. High molecular weight polymer was produced with weight‐averaged molecular weights varying between 600 000 and 1 500 000, depending on the line. Select lines were advanced to later generations yielding a line with 13.7% PHB in T₄ seeds. The levels of polymer produced in this study are the highest reported to date in a seed and are an important step forward for commercializing an oilseed‐based platform for PHB production.     

Germination responses of <Emphasis Type="Italic">Erica andevalensis</Emphasis> to different chemical and physical treatments

Erica andevalensis Cabezudo & Rivera is a threatened edaphic endemic species of Andalusia (SW Spain). Under natural conditions, the plants produce a very large number of small seeds (0.3–0.4 mm) but very few seedlings survive. Different treatments (high temperature, cold pre-treatment, nitrogen salts, and gibberellic acid applications) were tested to assess germination patterns in different populations and to determinate the most favorable conditions for germination. Gibberellic acid was provided in five different concentrations from 0 to 400 ppm GA₃, while nitrogen was applied as 10 mM of either KNO₃ or NH₄NO₃. The effect of pH on germination was also tested. The species always showed a low germination rate (6.50–22%) that was not stimulated either by 1 or 4 months in dry cold pre-treatment, nitrogen application, acid pH medium, or by high temperature (80°C for 10 min); although gibberellic acid application (100–400 ppm) significantly enhanced germination. The highest percentage of germination (41.6%) was achieved with a mean germination time to start germination (t ₀) of 7.6 ± 0.54 days when the seeds were subjected to 400 ppm gibberellic acid treatment. The population origin did not have a significant effect on germination percentage.     

Inactivation of Salmonella Typhimurium,Escherichia coli O157:H7 and Listeria monocytogenes on alfalfa seeds by the combination treatment of vacuumed hydrogen peroxide vapour and vacuumed dry heat

We evaluated the combined effects of vacuumed hydrogen peroxide vapour (VHPV) and vacuum-sealed dry heat (vacuum heat, VH) to inactivate food-borne pathogens (Salmonella Typhimurium, Escherichia coli O157:H7 and Listeria monocytogenes) on alfalfa seeds. Alfalfa seeds inoculated with food-borne pathogens were sequentially treated initially with 1·0 ml of 0 or 30% VHPV for 1 min and later with dry heat (DH) or VH for 2 h, and the rate of seed germination was evaluated. The combination treatment decreased the populations of three food-borne pathogens below the limit of detection (1·0 log CFU per gram) on alfalfa seeds without decreasing germinability. The sequential treatment using VHPV and VH greatly reduced the total treatment time needed to inactivate pathogens on alfalfa seeds by more than 5 log CFU per gram. These results demonstrate that a combination of VHPV and VH has potentially employed as a new method for pasteurization of alfalfa seeds without affecting their germinability.     

Survival of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium in manure and manure‐amended soil under tropical climatic conditions in Sub‐Saharan Africa

Aims: To establish the fate of Escherichia coli O157:H7 and Salmonella Typhimurium in manure and manure‐amended agricultural soils under tropical conditions in Sub‐Saharan Africa. Methods and Results: Survival of nonvirulent E. coli O157:H7 and Salm. Typhimurium at 4 and 7 log CFU g^?1 in manure and manure‐amended soil maintained at ≥80% r.h. or exposed to exclusive field or screen house conditions was determined in the Central Agro‐Ecological Zone of Uganda. Maintaining the matrices at high moisture level promoted the persistence of high‐density inocula and enhanced the decline of low‐density inocula in the screen house, but moisture condition did not affect survival in the field. The large majority of the survival kinetics displayed complex patterns corresponding to the Double Weibull model. The two enteric bacteria survived longer in manure‐amended soil than in manure. The 7 log CFU g^?1E. coli O157:H7 and Salm. Typhimurium survived for 49–84 and 63–98 days, while at 4 log CFU g^?1, persistence was 21–28 and 35–42 days, respectively. Conclusions: Under tropical conditions, E. coli O157:H7 and Salm. Typhimurium persisted for 4 and 6 weeks at low inoculum density and for 12 and 14 weeks at high inoculum density, respectively. Significance and Impact of the Study: Persistence in the tropics was (i) mostly shorter than previously observed in temperate regions thus suggesting that biophysical conditions in the tropics might be more detrimental to enteric bacteria than in temperate environments; (ii) inconsistent with published data isothermally determined previously hence indicating the irrelevance of single point isothermal data to estimate survival under dynamic temperature conditions.     

Effect of Vanadium on Testa,Seed Germination,and Subsequent Seedling Growth of Alfalfa (Medicago sativa L.)

Seed germination is the critical initial phase in the life cycle of plant and it is affected by various exogenous factors, including heavy metals. Seed germination and subsequent seedling growth of alfalfa (Medicago sativa L.) incubated in glass Petri dish in presence of elevated concentrations of pentavalent vanadium V(V) solution (0, 0.1, 0.5, 2, 4, 10, 50 mg L⁻¹ V, supplied as NaVO₃·2H₂O) were evaluated. Results showed that vanadium did not (P > 0.05) affect seed germination, final survival rate, and seedling height of alfalfa when exogenously treated dosages were ≤ 10 mg L⁻¹ V, whereas the root vitality and root elongation were distinctly inhibited at ≥ 0.5 mg L⁻¹ V treatments. A progressively deepened testa color at increasing vanadium concentrations during germination and an apparent modified structure of the seed coat at 50 mg L⁻¹ V compared to control in alfalfa were noted. Alfalfa seeds showed rapid and almost synchronous radicle emergence, independently of the vanadium concentration in the medium. The accumulation of vanadium in testa is beneficial to alleviate its toxicity to the seed germination of alfalfa. Leaf proline content was dramatically increased at ≥ 0.5 mg L⁻¹ V treatments compared with the control. Emerged seedlings displayed enough vigor and health to potentially colonize in the vanadium-contained matrix. Thus, alfalfa represents a good candidate for phytoremediation approach aimed at decontaminating environments when vanadium concentrations are within the determined thresholds.

     

Probiotic‐mediated competition,exclusion and displacement in biofilm formation by food‐borne pathogens

The objective of this study was to examine the inhibitory effect of probiotic strains on pathogenic biofilm formation in terms of competition, exclusion and displacement. Probiotic strains (Lactobacillus acidophilus KACC 12419, Lact. casei KACC 12413, Lact. paracasei KACC 12427 and Lact. rhamnosus KACC 11953) and pathogens (Salmonella Typhimurium KCCM 40253 and Listeria monocytogenes KACC 12671) were used to evaluate the auto‐aggregation, hydrophobicity and biofilm formation inhibition. The highest auto‐aggregation abilities were observed in Lact. rhamnosus (17·5%), Lact. casei (17·2%) and Lact. acidophilus (15·1%). Salm. Typhimurium had the highest affinity to xylene, showing the hydrophobicity of 53·7%. The numbers of L. monocytogenes biofilm cells during the competition, exclusion and displacement assays were effectively reduced by more than 3 log when co‐cultured with Lact. paracasei and Lact. rhamnosus. The results suggest that probiotic strains can be used as alternative way to effectively reduce the biofilm formation in pathogenic bacteria through competition, exclusion and displacement.

Significance and Impact of the Study

This study provides new insight into biofilm control strategy based on probiotic approach. Probiotic strains effectively inhibited the biofilm formation of Listeria monocytogenes through the mechanisms of competition, exclusion and displacement. These findings contribute to better understand the probiotic‐mediated competition, exclusion and displacement in biofilm formation by pathogens.     

Reduction of Escherichia coli O157:H7 on radish seeds by sequential application of aqueous chlorine dioxide and dry‐heat treatment

Aims: To assess the effectiveness of sequential treatments of radish seeds with aqueous chlorine dioxide (ClO₂) and dry heat in reducing the number of Escherichia coli O157:H7. Methods and Results: Radish seeds containing E. coli O157:H7 at 5·5 log CFU g^?1 were treated with 500 μg ml^?1 ClO₂ for 5 min and subsequently heated at 60°C and 23% relative humidity for up to 48 h. Escherichia coli O157:H7 decreased by more than 4·8 log CFU g^?1 after 12 h dry‐heat treatment. The pathogen was inactivated after 48 h dry‐heat treatment, but the germination rate of treated seeds was substantially reduced from 91·2 ± 5·0% to 68·7 ± 12·3%. Conclusions: Escherichia coli O157:H7 on radish seeds can be effectively reduced by sequential treatments with ClO₂ and dry heat. To eliminate E. coli O157:H7 on radish seeds without decreasing the germination rate, partial drying of seeds at ambient temperature before dry‐heat treatment should be investigated, and conditions for drying and dry‐heat treatment should be optimized. Significance and Impact of the study: This study showed that sequential treatment with ClO₂ and dry‐heat was effective in inactivating large numbers of E. coli O157:H7 on radish seeds. These findings will be useful when developing sanitizing strategies for seeds without compromising germination rates.     

Survival of Murine Norovirus,Tulane Virus,and Hepatitis A Virus on Alfalfa Seeds and Sprouts during Storage and Germination

Human norovirus (huNoV) and hepatitis A virus (HAV) have been involved in several produce-associated outbreaks and identified as major food-borne viral etiologies. In this study, the survival of huNoV surrogates (murine norovirus [MNV] and Tulane virus [TV]) and HAV was investigated on alfalfa seeds during storage and postgermination. Alfalfa seeds were inoculated with MNV, TV, or HAV with titers of 6.46 ± 0.06 log PFU/g, 3.87 ± 0.38 log PFU/g, or 7.01 ± 0.07 log 50% tissue culture infectious doses (TCID₅₀)/g, respectively. Inoculated seeds were stored for up to 50 days at 22°C and sampled during that storage period on days 0, 2, 5, 10, and 15. Following storage, virus presence was monitored over a 1-week germination period. Viruses remained infectious after 50 days, with titers of 1.61 ± 0.19 log PFU/g, 0.85 ± 0.21 log PFU/g, and 3.43 ± 0.21 log TCID₅₀/g for MNV, TV, and HAV, respectively. HAV demonstrated greater persistence than MNV and TV, without a statistically significant reduction over 20 days (<1 log TCID₅₀/g); however, relatively high levels of genomic copies of all viruses persisted over the testing time period. Low titers of viruses were found on sprouts and were located in all tissues as well as in sprout-spent water sampled on days 1, 3, and 6 following seed planting. Results revealed the persistence of viruses in seeds for a prolonged period of time, and perhaps of greater importance these data suggest the ease of which virus may transfer from seeds to sprouts and spent water during germination. These findings highlight the importance of sanitation and prevention procedures before and during germination.     

Inactivation of Bacillus cereus by Na‐chlorophyllin‐based photosensitization on the surface of packaging

Aims: This study was focused on the possibility to inactivate food‐borne pathogen Bacillus cereus by Na‐chlorophyllin (Na‐Chl)‐based photosensitization in vitro and after attachment to the surface of packaging material. Methods and Results: Bacillus cereus in vitro or attached to the packaging was incubated with Na‐Chl (7·5 × 10^?8 to 7·5 × 10^?5 mol l^?1) for 2–60 min in phosphate buffer saline. Photosensitization was performed by illuminating cells under a light with a λ of 400 nm and an energy density of 20 mW cm^?2. The illumination time varied 0–5 min and subsequently the total energy dose was 0–6 J cm^?2. The results show that B. cereus vegetative cells in vitro or attached to the surface of packaging after incubation with 7·5 × 10^?7 mol l^?1 Na‐Chl and following illumination were inactivated by 7 log. The photoinactivation of B. cereus spores in vitro by 4 log required higher (7·5 × 10^?6 mol l^?1) Na‐Chl concentration. Decontamination of packaging material from attached spores by photosensitization reached 5 log at 7·5 × 10^?5 mol l^?1 Na‐Chl concentration. Comparative analysis of different packaging decontamination treatments indicates that washing with water can diminish pathogen population on the surface by <1 log, 100 ppm Na‐hypochlorite reduces the pathogens about 1·7 log and 200 ppm Na‐hypochlorite by 2·2 log. Meanwhile, Na‐Chl‐based photosensitization reduces bacteria on the surface by 4·2 orders of magnitude. Conclusions: Food‐borne pathogen B. cereus could be effectively inactivated (7 log) by Na‐Chl‐based photosensitization in vitro and on the surface of packaging material. Spores are more resistant than vegetative cells to photosensitization‐based inactivation. Comparison of different surface decontamination treatments indicates that Na‐Chl‐based photosensitization is much more effective antibacterial tool than washing with water or 200 ppm Na‐hypochlorite. Significance and Impact of the Study: Our data support the idea that Na‐Chl‐based photosensitization has great potential for future application as an environment‐friendly, nonthermal surface decontamination technique.     

<Emphasis Type="Italic">In vitro</Emphasis> germination and micropropagation of <Emphasis Type="Italic">Givotia rottleriformis</Emphasis> Griff.

The propagation of Givotia rottleriformis Griff. is difficult as a result of long seed dormancy associated with poor seed germination. The present study was undertaken to develop a protocol to overcome seed dormancy by culture of zygotic embryo axes and then develop an efficient method for micropropagation of Givotia. Best germination frequency (78.3%) was achieved from mature zygotic embryo axes isolated from acid-scarified fresh seeds when cultured on Murashige and Skoog (MS) medium (half-strength major salts) with 28.9 μM gibberellic acid (GA₃). Efficient plant conversion was achieved by transfer of 10-d-old germinated embryos to MS medium (half-strength major salts) supplemented with 1.2 μM kinetin (KN) and 0.5 μM indole-3-butyric acid (IBA). However, acid scarification of 1-yr-old seeds decreased the germination frequency of zygotic embryo axes in comparison to those obtained from non-acid-scarified seeds which germinated (96.2%) and converted into plants (80.3%) on MS basal (half-strength major salts) medium. Multiple shoot bud induction was achieved by culture of shoot tips derived from in vitro germinated seedlings on MS medium with 0.5 μM thidiazuron for 4 wk, and the shoots elongated after transfer to a secondary medium with 1.2 μM KN. A maximum number of 7.8 shoots per explant with an average shoot length of 3.2 cm was achieved after two subcultures on this medium. The in vitro regenerated shoots rooted (41.5%) on half-strength MS medium with 0.5 μM IBA. The in vitro generated seedlings and micropropagated plants were established in soil with a survival frequency of 70% and 60%, respectively.     

Manganese sulfide nanospheres as mycocidal material and priming agent for fungi-infested rice seeds

Manganese sulfide nanospheres (MnS-NSs) prepared in situ via sonochemical process were characterized to investigate the effect of nanoscale MnS on antifungal potential against mycopathogens of rice viz. Fusarium verticillioides, Drechslera oryzae and Curvularia lunata. MnS-NSs dispersed in aqueous medium resulted in significant inhibition of growth of all the test fungi (ED₅₀ ≤ 18 μg/ml) at concentration much lower than standard commercial fungicides (captan and carbendazim with ED₅₀ ≥ 230 μg/ml) against respective fungi. The maximum per cent inhibition (98 ± 1.4) was recorded against C. lunata with a minimum ED₅₀ value of 14 μg/ml, followed by D. oryzae and F. verticillioides with ED₅₀ values of 17 and 18 μg/ml, respectively. Nanopriming of rice seeds with MnS-NSs at 35 μg/ml for 8 hr resulted in significant reduction in seed rot (76%) and seedling blight (89.13%) along with enhancement in percent germination, root length, shoot length, dry weight and vigour index of seedlings by 33.7%, 55%, 66.3%, 85.3% and 89.3%, respectively, compared with control. Hydropriming of seeds was found to control the seed health parameters less effectively than nanopriming.     

Cellular and molecular responses of Salmonella Typhimurium to antimicrobial-induced stresses during the planktonic-to-biofilm transition

Aim: To characterize the cellular and molecular properties of Salmonella Typhimurium exposed to antimicrobials in association with physicochemical property, biofilm formation ability and gene expression patterns. Methods and Results: The antimicrobial susceptibilities against Salmonella Typhimurium were evaluated to determine the MICs of allyl isothiocyanate (AITC), thymol, eugenol and polyphenol. Cell surface hydrophobicity, aggregation and biofilm formation assays were conducted to assess the physicochemical properties of Salm. Typhimurium treated with sublethal concentrations (SLC_2D) of antimicrobials. The expression patterns of adhesion‐related genes (adrA, csgD, fimA and lpfE), virulence‐related genes (hilA and stn) and efflux‐related genes (acrA, acrB, ompD and tolC) were evaluated by real‐time RT‐PCR. Thymol exhibited the highest antimicrobial activity against Salm. Typhimurium planktonic, biofilm and dispersed cells, showing 0·18, 0·96 and 0·42 mg ml^?1 of SLC_2D values, respectively. The antimicrobial‐treated Salm. Typhimurium showed low hydrophobicity. The highest auto‐aggregation ability (67%) of polyphenol‐treated Salm. Typhimurium was positively associated with the enhanced ability to form biofilms. The csgD, fimA, hilA and lpfE genes were up‐regulated in the polyphenol‐treated Salm. Typhimurium planktonic and biofilm cells. Conclusion: The results suggest that the antimicrobial resistance and virulence potential varied depending on the physiological states of Salm. Typhimurium during the transition from planktonic to biofilm cell growth. Significance and Impact of the Study: This study can expand our understanding of cellular and molecular mechanisms of biofilm formation and also provide useful information for reducing biofilm‐associated virulence potential.     

Anti-cyanobacterial activity of <Emphasis Type="Italic">Moringa oleifera</Emphasis> seeds

Filtrates from crushed Moringa oleifera seeds were tested for their effects on growth and Photosystem II efficiency of the common bloom-forming cyanobacterium Microcystis aeruginosa. M. aeruginosa populations exhibited good growth in controls and treatments with 4- and 8-mg crushed Moringa seeds per liter, having similar growth rates of 0.50 (±0.01) per day. In exposures of 20- to 160-mg crushed Moringa seeds L⁻¹, growth rates were negative and on average −0.23 (±0.05) .day⁻¹. Presumably, in the higher doses of 20- to 160-mg crushed seeds per liter, the cyanobacteria died, which was supported by a rapid drop in the Photosystem II efficiency (Φ_PSII), while the Φ_PSII was high and unaffected in 0, 4, and 8 mg L⁻¹. High-density populations of M. aeruginosa (chlorophyll-a concentrations of ∼270 μg L⁻¹) were reduced to very low levels within 2 weeks of exposure to ≥80-mg crushed seeds per liter. At the highest dosage of 160 mg L⁻¹, the Φ_PSII dropped to zero rapidly and remained nil during the course of the experiment (14 days). Hence, under laboratory conditions, a complete wipeout of the bloom could be achieved. This is the first study that yielded evidence for cyanobactericidal activity of filtrate from crushed Moringa seeds, suggesting that Moringa seed extracts might have a potential as an effect-oriented measure lessening cyanobacterial nuisance.     

Effects of <Emphasis Type="Italic">Lactobacillus buchneri</Emphasis> and <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> on fermentation,aerobic stability,bacteria diversity and ruminal degradability of alfalfa silage

Silages are important feedstuffs. Homofermentative lactic acid bacterial inoculants are often used to control silage fermentation. However, some research pointed out those homofermentative lactic acid bacteria (LAB) impaired the aerobic stability of wheat, sorghum, and corn silages. Adding heterofermentative LAB can produce more acetic acid, thereby stabilizing silages during aerobic exposure. Alfalfa is difficult to ensile. The present work was to study the effects of L. buchneri (heterofermentative LAB), alone or in combination with L. plantarum (homofermentative LAB) on the fermentation, aerobic stability, bacteria diversity and ruminal degradability of alfalfa silage. After 90 days ensiling, the pH, NH₃-N/TN, butyric acid content and molds counts of control were the highest. The inoculated silages had more lactic acid, acetic acid content and more lactic acid bacteria than the control. Inoculating LAB inhibited harmful microorganisms, such as Enterobacterium and Klebsiella pneumoniae. The L. buchneri + L. plantarum-inoculated silage had more acetic acid and less yeasts than other three treatments (P < 0.05), and lower NH₃-N/TN than control (P < 0.05). The CO₂ production of L. buchneri + L. plantarum-inoculated silage was less than that of L. plantarum-inoculated silage (P < 0.05). Inoculating LAB in alfalfa silages can decrease pH, increase the production of lactic and acetic acids, reduce the number of yeasts and molds, and inhibit Enterobacterium and K. pneumoniae. Inoculating with L. buchneri or L. buchneri + L. plantarum can improve aerobic stability of alfalfa silages. A combination of L. buchneri and L. plantarum is preferable because it enhanced alfalfa silage quality and aerobic stability.     

Effects of various pretreatments on seed germination of<Emphasis Type="Italic">Calystegia soldanella</Emphasis> (Convolvulaceae), a coastal sand dune plant

We tested various pretreatments to enhance the germination of ‘Sea bells’ (Calystegia soldanella Roem. et Schult). One experiment, which improved the germination rate by 70%, involved first scarifying the seed coats, then immersing the seeds in 50 ppm GA₃ for 24 h. A GA₃-alone pretreatment did not increase germination. However, the most effective method, with a 100% success rate, included 3 h of acid pretreatment with 98% H₂SO₄. We also used scanning electron microscopy (SEM) to examine the seed-coat surfaces and cross-sections of dry seeds. SEM showed structural differences between seeds that were not treated and those exposed to 98% H₂SO₄. The latter treatment allowed the seed coats to crack and break, thereby disrupting their physical dormancy.     

Water-soluble phenolic compounds in the coat control germination and peroxidase reactivation in <Emphasis Type="Italic">Triticum aestivum</Emphasis> seeds

In this work, we investigated the inhibitory effects of water-soluble phenolic compounds (WSPCs) in the coat of after-ripening wheat (Triticum aestivum L.) seeds on the processes of germination and peroxidase reactivation. Wheat bran has a WSPC content of 862.5 μg gallic acid equivalent g⁻¹ dry weight. When seeds were incubated in the water extract of bran, germination, peroxidase reactivation, and coleoptile and radicle growth were suppressed in a WSPC concentration-dependent manner. The inhibitory effects were significantly ameliorated by removing WSPCs from bran extract by treating with 1% insoluble polyvinylpolypyrrolidone. Pretreatment of seeds with 0.1% H₂O₂ reduced the WSPC content in the coat, which was confirmed using Fourier transform infrared microspectroscopy. With H₂O₂ pretreatment, seed germination, peroxidase reactivation, and post-germination seedling growth were significantly stimulated. Application of the known phenolics caffeic acid, feruic acid, or vanillin to the germination medium blocked seed germination and suppressed peroxidase reactivation. The results described here indicate that WSPCs act as endogenous inhibitors in the coat to control germination of Triticum aestivum seeds, and that inhibition of germination is at least partially caused by suppressing peroxidase reactivation.     

<Emphasis Type="Italic">Blighia unijugata</Emphasis> and <Emphasis Type="Italic">Luffa cylindrica</Emphasis> Seed Oils: Renewable Sources of Energy for Sustainable Development in Rural Africa

Self-sufficiency in energy requirement is critical to the success of any developing economy. Apart from the search for alternatives, there is a need to achieve energy independence, directing much focus on biofuels. Biodiesel is simple to use, biodegradable, nontoxic, and essentially free of sulfur and aromatics. Oil was extracted from the seeds of Blighia unijugata and Luffa cylindrica, subjected to chemical characterization and biodiesel production. The oil yield from the seed of B. unijugata was 50.82 ± 1.20% while that of L. cylindrica was 39.10 ± 0.20%. The biodiesel produced had ester content above 98%. The flash point of the biodiesel from B. unijugata and L. cylindrica was above 120°C while the phosphorus content was also below 1 ppm in both cases. The oxidative stability of B. unijugata was 44.30 ± 0.30 h, while that of L. cylindrica was lower than this value due to its high unsaturation. The copper strip corrosion value of the biodiesel was also found to be 1A. This study showed that the high free fatty acid content of B. unijugata and L. cylindrica seed oil can be reduced in a one-step pretreatment of esterification reaction using H₂SO₄ as catalyst thus reducing the problem of soap formation encountered when using oil with high free fatty acid for the production of biodiesel.     

Pogonomyrmexcunicularius as the keystone disperser of elaiosome‐bearing Jatropha excisa seeds in semi‐arid Argentina

Myrmecochory or seed dispersal by ants is often described as a diffuse mutualism, because many of the ant species that function as partners are considered to be similar in terms of the frequency and consequences of their interactions. In this work, we test this assumption by conducting ant community surveys and seed removal experiments in six study sites located within a semi‐arid region of northwest Argentina. At each site, we characterized the ant assemblage that interacted with the seeds of Jatropha excisa Griseb. (Euphorbiaceae), an ant‐dispersed native shrub. Our results demonstrate that seed removal was dominated by one species, Pogonomyrmex cunicularius Mayr (Hymenoptera: Formicidae: Myrmicinae), which was responsible of 84% of the observed seed removal events. Although several ant species were attracted to the elaiosome‐bearing seeds of J. excisa, seed removal did not depend on ant community composition (species richness and ant activity) but was significantly influenced by the abundance of P. cunicularius. Its physical, behavioral, and ecological attributes are common with other ant species that have been characterized as keystone seed dispersers in other regions of the world. Nest feeding with marked seeds revealed that once P. cunicularius ants consume the elaiosomes, seeds are left inside the nests undamaged and at an appropriate depth for emergence. Our results support the hypothesis that myrmecochory is often an unevenly diffuse mutualism (i.e., one partner species is particularly important) and that at a local scale P. cunicularius is the keystone seed disperser of J. excisa.