Exploring virulence of new and less studied species of <Emphasis Type="Italic">Metarhizium</Emphasis> spp. from Brazil for two-spotted spider mite control

The two-spotted spider mite Tetranychus urticae is an important pest of strawberry crops in Brazil and many other countries. Focus for biocontrol studies involving entomopathogenic fungi has been on three species from the genus Metarhizium: M. anisopliae sensu stricto (s.s.), M. brunneum and M. robertsii. Also, the species Beauveria bassiana has been studied for spider mite control and one isolate (ESALQPL63) is commercially available in Brazil. New and undescribed Metarhizium species have been found recently in Brazil and provide a pool of isolates with potential for biocontrol in Brazil and probably also elsewhere. The mortality of adult females of T. urticae when exposed to four new Brazilian species of Metarhizium was compared to the mortality when exposed to M. anisopliae s.s., M. brunneum, M. pingshaense, M. robertsii and Beauveria bassiana ESALQPL63. Fungal suspensions were sprayed onto mites at 10⁷ conidia/mL with 0.05% Tween 80 in laboratory bio-assays. We measured total mortality and percentage sporulating cadavers 10 days after exposure and calculated median lethal time (LT₅₀). The lowest LT₅₀ (4.0 ± 0.17) was observed for mites treated with Metarhizium sp. Indet. 1 (ESALQ1638), which also performed well with respect to mortality after 10 days and capacity to sporulate from cadavers. Among the other little studied species tested, M. pingshaense (ESALQ3069 and ESALQ3222) and Metarhizium Indet. 2 (ESALQ1476) performed well and were comparable to B. bassiana (ESALQPL63). The new Metarhizium isolates and species thus showed potential for biological control.     

Comparative study between Larval Packet Test and Larval Immersion Test to assess the effect of <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> on <Emphasis Type="Italic">Rhipicephalus microplus</Emphasis> tick larvae

Entomopathogenic fungi, such as Metarhizium anisopliae, for the control of arthropods, have been studied for more than 20 years. The aim of this study was to determine the best methodology to evaluate the in vitro effect of the fungus M. anisopliae on Rhipicephalus microplus tick larvae. We compared a modified Larval Packet Test (LPT) and a Larval Immersion Test (LIT). For the LPT filter papers were impregnated with 1 mL of M. anisopliae suspension in Triton X-100 at 0.02%, in concentrations of 10⁶, 10⁷ and 10⁸ conidia/mL and subsequently folded to include the larval ticks. LIT was performed by immersing the larvae in M. anisopliae suspensions for 5 min using the same three concentrations, then the larvae were placed on filter paper clips. For LPT, the LT₅₀ values obtained were 134.6, 27.2 and 24.8 days for concentrations of 10⁶, 10⁷ and 10⁸ conidia/mL; and the mortality after 21 days was 17.3, 17.6 and 38%, respectively. The LT₅₀ values of LIT were 24.5, 20 and 9.2 days with mortality after 21 days of 50.5, 64.7 and 98% for 10⁶, 10⁷ and 10⁸ conidia/mL, respectively. For the same conidia concentration, LIT showed a higher mortality in a shorter time interval when compared with LPT. These differences between the methods tested must be taking into account in further screening and effect studies with M. anisopliae. The set of results shown here could optimize the protocol used to identify M. anisopliae strains pathogenic against R. microplus.     

Factors determining active dispersal capacity of adult Chinese mitten crab <Emphasis Type="Italic">Eriocheir sinensis</Emphasis> (Decapoda,Varunidae)

The Chinese mitten crab (Eriocheir sinensis) is an invasive crustacean with a widespread distribution, sometimes overlapping with the red swamp crayfish (Procambarus clarkii). E. sinensis performs long river migrations, often moving overland to cross obstacles, but the factors affecting its movement are not well known. We studied its movement speed in and out of water, the survival time out of water and also its interaction with the red swamp crayfish during dispersal. At 16°C the LT₅₀ (time to death of 50% of the individuals) was 70 h, with a mean weight loss of 20%, and at 24°C the LT₅₀ was 31 h, with a mean 22% weight loss. In and out of the water, these crabs moved with mean velocities of 0.074 and 0.016 m s^?1, respectively. P. clarkii did not affect the dispersion of E. sinensis. This crab was able to disperse under various environmental conditions and its speed was affected by density, temperature, relative humidity, carapace length, and condition of the individuals (Fulton index). Moreover, we found that this species has a great capacity to resist desiccation. These characteristics give them all the requirements to successfully invade and adapt to new areas.     

Bacterial metabolites from intra- and inter-species influencing thermotolerance: the case of <Emphasis Type="Italic">Bacillus cereus</Emphasis> and <Emphasis Type="Italic">Geobacillus stearothermophilus</Emphasis>

Bacterial metabolites with communicative functions could provide protection against stress conditions to members of the same species. Yet, information remains limited about protection provided by metabolites in Bacillus cereus and inter-species. This study investigated the effect of extracellular compounds derived from heat shocked (HS) and non-HS cultures of B. cereus and Geobacillus stearothermophilus on the thermotolerance of non-HS vegetative and sporulating B. cereus. Cultures of B. cereus and G. stearothermophilus were subjected to HS (42 or 65 °C respectively for 30 min) or non-HS treatments. Cells and supernatants were separated, mixed in a combined array, and then exposed to 50 °C for 60 min and viable cells determined. For spores, D values (85 and 95 °C) were evaluated after 120 h. In most cases, supernatants from HS B. cereus cultures added to non-HS B. cereus cells caused their thermotolerance to increase (D ₅₀ 12.2–51.9) when compared to supernatants from non-HS cultures (D ₅₀ 7.4–21.7). While the addition of supernatants from HS and non-HS G. stearothermophilus cultures caused the thermotolerance of non-HS cells from B. cereus to decrease initially (D ₅₀ 3.7–7.1), a subsequent increase was detected in most cases (D ₅₀ 18–97.7). In most cases, supernatants from sporulating G. stearothermophilus added to sporulating cells of B. cereus caused the thermotolerance of B. cereus 4810 spores to decline, whereas that of B. cereus 14579 increased. This study clearly shows that metabolites in supernatants from either the same or different species (such as G. stearothermophilus) influence the thermotolerance of B. cereus.     

Extracellular Synthesis and Characterization of Gold Nanoparticles Using <Emphasis Type="Italic">Mycobacterium</Emphasis> sp. BRS2A-AR2 Isolated from the Aerial Roots of the Ghanaian Mangrove Plant, <Emphasis Type="Italic">Rhizophora racemosa</Emphasis>

Through the use of genomes that have undergone millions of years of evolution, marine Actinobacteria are known to have adapted to rapidly changing environmental pressures. The result is a huge chemical and biological diversity among marine Actinobacteria. It is gradually becoming a known fact that, marine Actinobacteria have the capability to produce nanoparticles which have reasonable sizes and structures with possible applications in biotechnology and pharmacology. Mycobacterium sp. BRS2A-AR2 was isolated from the aerial roots of the mangrove plant Rhizophora racemosa. The Mycobacterium was demonstrated for the first time ever to produce AuNPs with sizes that range between 5 and 55 nm. The highest level absorbance of the biosynthesized AuNPs was typical for actinobacterial strains (2.881 at 545 nm). The polydispersity index was measured as 0.207 in DLS and the zeta potential was negatively charged (? 28.3 mV). Significant vibration stretches were seen at 3314, 2358, 1635 and 667 cm^?1 in FT-IR spectra. This demonstrated the possible use of small aliphatic compounds containing –COOH, –OH, –Cl and –NH₂ functional groups in the stabilization of the AuNPs. The effect of the biosynthesized AuNPs on HUVEC and HeLA cell lines was measured at 48 h. IC₅₀ values were determined at 3500 µg/ml concentration for HUVEC and HeLA cell lines at 45.25 and 53.41% respectively.     

First study on characterization of virulence and antibiotic resistance genes in verotoxigenic and enterotoxigenic <Emphasis Type="Italic">E</Emphasis>. <Emphasis Type="Italic">coli</Emphasis> isolated from raw milk and unpasteurized traditional cheeses in Romania

The study focused on the incidence of enterotoxigenic Escherichia coli (ETEC) and verotoxigenic E. coli (VTEC) in raw milk and traditional dairy cheeses marketed in Romania, characterizing the virulence and antibiotic resistance genes of these isolates. One hundred and twenty samples of raw milk and 80 samples of unpasteurized telemy cheese were collected and cultured according to the international standard protocol. All the characteristic E. coli cultures were analyzed for the presence of STa, STb, LT, stx1, and stx2 toxicity genes. The ETEC/VTEC strains were tested for the presence of antibiotic resistance genes, such as aadA1, tetA, tetB, tetC, tetG, dfrA1, qnrA, aaC, sul1, bla _SHV , bla _CMY , bla _TEM , and ere(A), using PCR. The results showed that 27 samples (18.62%) were positive for one of the virulence genes investigated. 48.1% (n = 13) tested positive at the genes encoding for tetracycline resistance, tetA being the most prevalent one (61.5%; n = 8). A high percent (33.3%; n = 9) revealed the beta-lactamase (bla _TEM ) resistance gene, and none of the samples tested positive for bla _CMY and bla _SHV genes. The genes responsible for resistance to sulfonamides (sul1) and trimethoprim (dfrA1) were detected in rates of 14.8% (n = 4) and 7.4% (n = 2), respectively. E. coli is highly prevalent in raw milk and unpasteurized cheeses marketed in Romania. These strains might represent an important reservoir of resistance genes which can easily spread into other European countries, given the unique market.     

Contrasting δ<Superscript>15</Superscript>N Values of Atmospheric Deposition and <Emphasis Type="Italic">Sphagnum</Emphasis> Peat Bogs: N Fixation as a Possible Cause

Nitrogen (N) isotope systematics were investigated at two high-elevation ombrotrophic peat bogs polluted by farming and heavy industry. Our objective was to identify N sources and sinks for isotope mass balance considerations. For the first time, we present a time-series of δ¹⁵Ν values of atmospheric input at the same locations as δ¹⁵Ν values of living Sphagnum and peat. The mean δ¹⁵Ν values systematically increased in the order: input NH₄ ⁺ (?10.0‰) < input NO₃ ^? (?7.9‰) < peat porewater (?5.6‰) < Sphagnum (?5.0‰) < shallow peat (?4.2‰) < deep peat (?2.2‰) < runoff (?1.4‰) < porewater N₂O (1.4‰). Surprisingly, N of Sphagnum was isotopically heavier than N of the atmospheric input (P < 0.001). If partial incorporation of reactive N from the atmosphere into Sphagnum was isotopically selective, the residual N would have to be isotopically extremely light. Such N, however, was not identified anywhere in the ecosystem. Alternatively, Sphagnum may have contained an admixture of isotopically heavier N. Ambient air contains such N in the form of N₂ (δ¹⁵Ν_N2 = 0‰). Because high energy is required to break the triple bond, microbial N fixation is likely to proceed only under limited availability of pollutant N. Also for the first time, a δ¹⁵Ν comparison is presented between anoxic deeper peat and porewater N₂O. Isotopically light N is removed from anoxic substrate by denitrification, whose final product, N₂, escapes into the atmosphere. Porewater N₂O is an isotopically heavy residuum following partial N₂O reduction to N₂.     

Dose rate effects of low-LET ionizing radiation on fish cells

Radiobiological responses of a highly clonogenic fish cell line, eelB, to low-LET ionizing radiation and effects of dose rates were studied. In acute exposure to 0.1–12 Gy of gamma rays, eelB’s cell survival curve displayed a linear–quadratic (LQ) relationship. In the LQ model, α, β, and α/β ratio were 0.0024, 0.037, and 0.065, respectively; for the first time that these values were reported for fish cells. In the multi-target model, n, D _o, and D _q values were determined to be 4.42, 2.16, and 3.21 Gy, respectively, and were the smallest among fish cell lines being examined to date. The mitochondrial potential response to gamma radiation in eelB cells was at least biphasic: mitochondria hyperpolarized 2 h and then depolarized 5 h post-irradiation. Upon receiving gamma rays with a total dose of 5 Gy, dose rates (ranging between 83 and 1366 mGy/min) had different effects on the clonogenic survival but not the mitochondrial potential. The clonogenic survival was significantly higher at the lowest dose rate of 83 mGy/min than at the other higher dose rates. Upon continuous irradiation with beta particles from tritium at 0.5, 5, 50, and 500 mGy/day for 7 days, mitochondria significantly depolarized at the three higher dose rates. Clearly, dose rates had differential effects on the clonogenic survival of and mitochondrial membrane potential in fish cells.     

Xylem anatomy and calculated hydraulic conductance of four <Emphasis Type="Italic">Nothofagus</Emphasis> species with contrasting distribution in South-Central Chile

Nothofagus obliqua, N. dombeyi, N. alpina and N. antarctica are characteristic tree species of the temperate forests on the western slopes of the Andes with centres of distribution that differ in their temperature and moisture regimes. We tested branch wood from co-occurring specimens of these species for the inherent differences in xylem anatomy and theoretical hydraulic conductance to evaluate their resistance to drought or frost. The hydraulic conductivity of the xylem was calculated using a modified Hagen–Poiseuille equation and related to wood density. Conduit dimensions were used to predict the water potential that would cause 50 % loss of hydraulic conductivity (Ψ ₅₀). Nothofagus alpina, which mainly grows at sites with low frost frequency, exhibited the largest conduits and the highest mean values for conduit area, fraction of conduit area in the cross-section and hydraulic conductivity, but the lowest wood density. Opposite relationships were found in the plastic N. antarctica, whose xylem seems to be least vulnerable to freezing-induced, but also to drought-induced embolism. Calculated Ψ ₅₀ was highest (least negative) in N. alpina, indicating a relatively high susceptibility to cavitation. The xylem of the thermophilic N. obliqua and of N. dombeyi, which mainly occurs under oceanic climate, but can also survive at sporadically dry and warm sites, is not particularly adapted to periods of drought stress. Across all species, wood density was negatively correlated with the calculated hydraulic conductance. The xylem traits of N. alpina might contribute to its relatively high growth rate and facilitate its spread into forest gaps.     

Modeling seed germination of unprimed and primed seeds of sweet sorghum under PEG-induced water stress through the hydrotime analysis

The effects of reduced water potential (ψ) on seed germination at 25 and 15 °C in unprimed (UP) and primed (P) seeds of two cultivars of sweet sorghum (cv. Keller and cv. Makueni local), were analyzed through the hydrotime model. Six ψ (from 0 to ?1.0 MPa) in polyethylene glycol 6000 (PEG) solutions were used for the tests. Seeds were primed in 250 g/L PEG solution at 15 °C for 48 h. Decreasing ψ of imbibition solution reduced and delayed germination. At 15 °C seeds germinated less and slower than at 25 °C at any ψ. Seeds of cv. Makueni local exhibited a greater sensitivity to water stress in terms of germination percentage, than seeds of cv. Keller, but they were faster in germination. Osmopriming was beneficial for seed germination, both in terms of final percentage and rate, at any temperature and ψ. The hydrotime analysis revealed that predicted θ _H constant was increased when temperature was reduced to 15 °C and at this temperature median base water potential [ψ _b(50)] for germination was higher (less negative) than at 25 °C. Seed priming shifted ψ _b(50) towards more negative values and reduced θ _H requirements for germination. At 25 °C the two cultivars behaved similarly while at 15 °C cv. Keller exhibited a ψ _b more negative but required a greater θ _H to germinate, indicating a greater water-stress tolerance but a slower germination, than cv. Makueni local. The application of the model allows to identify water stress tolerant cultivars during germination, to include into breeding programs for the selection of well-performing cultivars under stress conditions.     

Genetic population structure and low genetic diversity in the over-exploited sea cucumber <Emphasis Type="Italic">Holothuria edulis</Emphasis> Lesson, 1830 (Echinodermata: Holothuroidea) in Okinawa Island

Understanding genetic connectivity is fundamental for ecosystem-based management of marine resources. Here we investigate the metapopulation structure of the edible sea cucumber Holothuria edulis Lesson, 1830 across Okinawa Island, Japan. This species is of economic and ecological importance and is distributed from the Red Sea to Hawai‘i. We examined sequence variation in fragments of mitochondrial cytochrome oxidase subunit I (COI) and 16S ribosomal RNA (16S), and nuclear histone (H3) at six locations across Okinawa Island. We found higher haplotype diversity for mtDNA (COI: Hd = 0.69 and 16S: Hd = 0.67) and higher heterozygosity of nDNA (H3: H _E = 0.39) in populations from the west coast of Okinawa compared to individuals from populations on the east coast (COI: Hd = 0.40; 16S: Hd = 0.21; H3: H _E = 0.14). Overall population structure was significant (AMOVA results for COI: Φ _ST = 0.49, P < 0.0001; 16S: Φ _ST = 0.34, P < 0.0001; H3: Φ _ST = 0.12, P < 0.0001). One population in the east, Uruma, showed elevated pairwise Φ _ST values in comparisons with all other sites and a marked reduction of genetic diversity (COI: Hd = 0.25 and 16S: Hd = 0.24), possibly as a consequence of a shift to a more dominant asexual reproduction mode. Recent reports have indicated that coastal development in this area influences many marine organisms, and ecosystem degradation in this location could cause the observed decrease of genetic diversity and isolation of H. edulis in Uruma. Our study should provide valuable data to help with the urgently needed management of sea cucumber populations in Okinawa, and indicates particular attention needs to be paid to vulnerable locations.     

Using hydrothermal time concept to describe sesame (<Emphasis Type="Italic">Sesamum indicum</Emphasis> L.) seed germination response to temperature and water potential

To quantify both temperature (T) and water potential (ψ) effects on sesame (Sesamum indicum L.) seed germination (SG) and also to determine the cardinal T _s for this plant, a laboratory experiment was carried out using hydrothermal time model (HTT). For this purpose, four sesame cultivars (‘Asbomahalleh’, ‘Darab’, ‘Dashtestan’ and ‘Yellowhite’) were germinated at seven constant T _s (20, 25, 30, 35, 37, 39 and 43 °C) at each of the following ψ _s (0, ? 0.12, ? 0.24 and ? 0.36 MPa; provided by PEG 8000). Germination rate (GR) and germination percentage (GP) significantly influenced by ψ, T and their interactions in all cultivars (P ≤ 0.01). There was no significant difference, based on the confidence intervals of the model coefficients, between cultivars, so an average of cardinal T _s was 14.7, 35.4 and 47.2 °C for the minimum (T _b), optimum (T _o) and maximum (T _c) T _s, respectively, in the control condition (0 MPa). Hydrotime values in all cultivars decreased when T was increased to T _o and then remained constant at T _s > T _o (15 MPa h^?1). An average value of ψ _b(50) was estimated to be ? 1.23 MPa at T _s ≤ T _o and then increased linearly (0.1041 MPa°Ch^?1, the slope of the relationship between ψ _b(50) and supra-optimal T _s) with T when T _s increased above T _o and finally reached to zero at T _c. The T _b and T _o values were not influenced by ψ, but T _c value decreased (from 47.2 for zero to 43.5 °C for ? 0.36 MPa) at supra-optimal T _s as a result of the effect of ψ on GR. Based on our findings, this model (as a predictive tool) and or the estimated parameter values in this study can easily be used in sesame SG simulation models to quantitatively characterize the physiological status of sesame seed populations at different T _s and ψ _s.     

Estimating stable carbon isotope values of microphytobenthos in the Arctic for application to food web studies

Most studies on Arctic food webs have neglected microphytobenthos as a potential food source because we currently lack robust measurements of δ¹³C values for microphytobenthos from this environment. As a result, the role of microphytobenthos in high latitude marine food webs is not well understood. We combined field measurements of the concentration of aqueous carbon dioxide and the stable carbon isotopic composition of dissolved inorganic carbon (δ¹³C_DIC) from bottom water in the Beaufort and Chukchi seas with a set of stable carbon isotopic fractionation factors reflecting differences in algal taxonomy and physiology to estimate the stable carbon isotope composition of microphytobenthos-derived total organic carbon (δ¹³C_p). The δ¹³C_p for Phaeodactylum tricornutum, a pennate diatom likely to be a dominant microphytobenthos taxon, was estimated to be ?23.9 ± 0.4 ‰ as compared to a centric diatom (Porosira glacialis, δ¹³C_p = ?20.0 ± 1.6 ‰) and a marine haptophyte (Emiliana huxleyi, δ¹³C_p = ?22.7 ± 0.5 ‰) at a growth rate (µ) of 0.1 divisions per day (d^?1). δ¹³C_p values increased by ~2.5 ‰ when µ increased from 0.1 to a maximum growth rate of 1.4 d^?1. We compared our estimates of δ¹³C_p values for microphytobenthos with published measurements for other carbon sources in the Arctic and sub-Arctic. We found that microphytobenthos values overlapped with pelagic sources, yet differed from riverine and ice-derived carbon sources. These model results provide valuable insight into the range of possible isotopic values for microphytobenthos from this region, but we remain cautious in regard to the conclusiveness of these findings given the paucity of field measurements currently available for model validation.     

Assessing biodegradation of furfuryl alcohol using <Emphasis Type="Italic">Pseudomonas putida</Emphasis> MTCC 1194 and <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> MTCC 1034 and its kinetics

The biodegradation of furfuryl alcohol (FA) in shake flask experiments using a pure culture of Pseudomonas putida (MTCC 1194) and Pseudomonas aeruginosa (MTCC 1034) was studied at 30 °C and pH 7.0. Experiments were performed at different FA concentrations ranging from 50 to 500 mg/l. Before carrying out the biodegradation studies, the bacterial strains were acclimatized to the concentration of 500 mg/l of FA by gradually raising 100 mg/l of FA in each step. The well acclimatized culture of P. putida and P. aeruginosa degraded about 80 and 66% of 50 mg/l FA, respectively. At higher concentration of FA, the percentage of FA degradation decreased. The purpose of this study was to determine the kinetics of biodegradation of FA by measuring biomass growth rates and concentration of FA as a function of time. Substrate inhibition was calculated from experimental growth parameters using the Haldane equation. Data for P. putida were determined as µ _max ?=?0.23 h^?1, K _s ?=?23.93 mg/l and K _i ?=?217.1 mg/l and for P. aeruginosa were determined as µ _max ?=?0.13 h^?1, K _s ?=?21.3 mg/l and K _i ?=?284.9 mg/l. The experimental data were fitted in Haldane, Aiba and Edwards inhibition models.     

Characterization and virulence of <Emphasis Type="Italic">Lecanicillium lecanii</Emphasis> against different aphid species

Seven isolates of Lecanicillium lecanii (Zimmermann) Zare &; Gams isolated in Spain from infected aphids were characterized using sequences of the Internal Transcribed Spacer (ITS) regions and also based on morphological and physiological characteristics. Four of these seven L. lecanii isolates were selected to assess their virulence against nymphs of Myzus persicae (Sulzer), Nasonovia ribisnigri (Mosley), Macrosiphum euphorbiae (Thomas) and Aphis gossypii Glover. Mortality (%), lethal concentration 50 (LC₅₀) and lethal time 50 (TC₅₀) were calculated. The analysis of the sequences of ITS region confirmed that the new isolates were clearly Lecanicillium lecanii. The set of isolates had similar radial growth (51.5–54.0 mm), except for ICAL1 (39 mm). The germination time 50 (GT₅₀) varied between 10.7 h (ICAL3) and 13 h (ICAL5). The isolate ICAL6 showed the highest value for conidial production (3.4 × 10⁸ con ml^?1) and also produced the highest mortality for M. persicae (95%) and was more virulent than the commercial product Vertalec^® (91.6%).     

The efficacy and sterilisation of human decellularised dermal allografts with combinations of cupric ions and hydrogen peroxide

Decellularised tissue allografts have been used in reconstructive surgical applications and transplantation for many years. Some of the current methods of sterilisation have a detrimental effect on the tissue graft structure and function. The anti-microbial activity of cupric ions and hydrogen peroxide (H₂O₂) are well known however their combined application is not currently utilised as a decontamination agent in the tissue banking world sector. The aim of this study was to determine the combined concentrations of copper chloride (CuCl₂) and H₂O₂ that have the optimal bactericidal and sporicidal activity on decellularised (dCELL) human dermis. The first part of this study established the decimal reduction time (D-value) of CuCl₂ (0.1 mg/L and 1 mg/L) together with H₂O₂ (0.01, 0.1, 0.5 and 1%) for Staphylococcus epidermidis, Escherichia coli and Bacillus subtilis spores. The second part of this study identified the most effective CuCl₂ and H₂O₂ concentration that decontaminated dCELL human dermis inoculated with these pathogens. Of all the concentrations tested, 0.1 mg/L CuCl₂ in combination with 1% H₂O₂ had the shortest D-value; S. epidermidis D = 3.15 min, E. coli D = 2.62 min and B. subtilis spores D = 18.05 min. However when adsorbed onto dCELL dermis, S. epidermidis and E. coli were more susceptible to 1 mg/L CuCl₂ together with 0.5% H₂O₂. These studies show promise of CuCl₂–H₂O₂ formulations as potential sterilants for decellularised dermal allografts.     

Hydrothermal time analysis of watermelon (<Emphasis Type="Italic">Citrullus vulgaris</Emphasis> cv. ‘Crimson sweet’) seed germination

This study evaluated the ability of a hydrothermal time model (HTT) to describe the kinetics of watermelon (Citrullus vulgaris cv. ‘Crimson sweet’) seed germination under different temperatures (T) and water potentials (ψ) and also to determine the cardinal temperatures of watermelon. Results indicated that ψ influenced germination rate and germination percentage. For this seed lot, cardinal temperatures were 10 °C for T _b, 28.34 °C for T _o and 40.8 °C for T _c in the control (0 MPa) treatment. There was a decrease in hydrotime constant (θ _H) when T was increased to T _o and then remained constant at supra-optimal temperatures (30 MPah^?1). Also, at temperatures above T _o, ψ _b(50) values increased linearly with T. The k _T value (the slope of the relationship between ψ _b(50) and T exceeds T _o) of this seed lot was calculated as 0.076 MPa°Ch^?1. Results this study show that when the HTT model is applied, it can accurately describe ψ _b(g) and the course of germination around Ts (R ² = 0.82). Moreover, the ψ _b(50) was estimated to be ?0.96 MPa based on this model. Consequently, the germination response of watermelon for all Ts and ψs can be adequately described by the HTT model and enabling it to be used as a predictive tool in watermelon seed germination simulation models.     

Evaluation of Potential Probiotics Isolated from Human Milk and Colostrum

Several studies have demonstrated a diversity of bacterial species in human milk, even in aseptically collected samples. The present study evaluated potential probiotic bacteria isolated from human milk and associated maternal variables. Milk samples were collected from 47 healthy women and cultured on selective and universal agar media under aerobic and anaerobic conditions. Bacterial isolates were counted and identified by Biotyper Matrix-Assisted Laser Desorption Ionization–Time of Flight mass spectrometry and then tested for probiotic properties. Total bacteria in human milk ranged from 1.5 to 4.0 log₁₀ CFU/mL. The higher bacterial counts were found in colostrum (mean = 3.9 log₁₀ CFU/mL, 95% CI 3.14–4.22, p = 0.00001). The most abundant species was Staphylococcus epidermidis (n = 76). The potential probiotic candidates were Lactobacillus gasseri (n = 4), Bifidobacterium breve (n = 1), and Streptococcus salivarius (n = 4). Despite the small sample size, L. gasseri was isolated only in breast milk from mothers classified into a normal weight range and after a vaginally delivered partum. No potential probiotics showed antagonism against pathogens, but all of them agglutinated different pathogens. Nine bacterial isolates belonging to the species L. gasseri, B. breve, and S. salivarius were selected as potential probiotics. The present study confirms the presence in breast milk of a bacterial microbiota that could be the source of potential probiotic candidates to be used in the formula of simulated maternal milk.     

Novel aromatic polyketides from soil <Emphasis Type="Italic">Streptomyces</Emphasis> spp.: purification,characterization and bioactivity studies

Aromatic polyketides are important therapeutic compounds which include front line antibiotics and anticancer drugs. Since most of the aromatic polyketides are known to be produced by soil dwelling Streptomyces, 54 Streptomyces strains were isolated from the soil samples. Five isolates, R1, B1, R3, R5 and Y8 were found to be potent aromatic polyketide producers and were identified by 16S rRNA gene sequencing as Streptomyces spectabilis, Streptomyces olivaceus, Streptomyces purpurascens, Streptomyces coeruleorubidus and Streptomyces lavendofoliae respectively. Their sequences have been deposited in the GenBank under the accession numbers KF468818, KF681280, KF395224, KF527511 and KF681281 respectively. The Streptomyces strains were cultivated in the media following critically optimised culture conditions. The resulting broth extracts were fractionated on a silica gel column and preparative TLC to obtain pure compounds. The pure compounds were tested for bioactivity and the most potent compound from each isolate was identified by UV–Vis, IR and NMR spectroscopic methods. Isolated S. spectabilis (R1), yielded one potent compound identified as dihydrodaunomycin with an MIC of 4 µg/ml against Bacillus cereus and an IC₅₀ value of 24 µM against HeLa. S. olivaceus (B1), yielded a comparatively less potent compound, elloramycin. S. purpurascens (R3) yielded three compounds, rhodomycin, epelmycin and obelmycin. The most potent compound was rhodomycin with an MIC of 2 µg/ml against B. cereus and IC₅₀ of 15 µM against HeLa. S. coeruleorubidus (R5), yielded daunomycin showing an IC₅₀ of 10 µM and also exhibiting antimetastatic properties against HeLa. S. lavendofoliae (Y8), yielded a novel aclacinomycin analogue with IC₅₀ value of 2.9 µM and potent antimetastatic properties at 1 µM concentration against HeLa. The study focuses on the characterization of aromatic polyketides from soil Streptomyces spp., which can serve as potential candidates for development of chemotherapeutic drugs in future.     

Characterization of chickpea (<Emphasis Type="Italic">Cicer arietinum</Emphasis> L.) lectin for biological activity

Lectins are proteins that are subject of intense investigations. Information on lectin from chickpea (Cicer arietinum L.) with respect to its biological activities are very limited. In this study, we purified lectin from the seeds of chickpea employing DEAE-cellulose and SP-Sephadex ion exchange chromatography and identified its molecular subunit mass as 35 kDa. The free radical scavenging activity of lectin measured by the DPPH assay has IC₅₀ of 0.88 µg/mL. Lectin exerted antifungal activity against Candida krusei, Fusarium oxysporium oxysporium, Saccharomyces cerevisiae and Candida albicans, while antibacterial activity against E. coli, B. subtilis, S. marcescens and P. aeruginosa. The minimum inhibitory concentrations were 200, 240, 160 and 140 µg for C. krusei, F. oxysporium, S. cerevisiae and C. albicans respectively. Lectin was further examined for its antiproliferative potential against cancerous cell line. The cell viability assay indicated a high inhibition activity on Ishikawa, HepG2, MCF-7 and MDA-MB-231 with IC₅₀ value of 46.67, 44.20, 53.58 and 37.46?µg/mL respectively. These results can provide a background for future research into the benefits of chickpea lectin to pharmacological perspective.