Inoculum Conditions Research Articles

Biogas potential of residues generated by the tomato processing industry under different substrate and inoculum conditions

Biogas potential of residues generated by the tomato processing industry under different substrate and inoculum conditions

Microbial communities mediating algal detritus turnover under anaerobic conditions.

BackgroundAlgae encompass a wide array of photosynthetic organisms that are ubiquitously distributed in aquatic and terrestrial habitats. Algal species often bloom in aquatic ecosystems, providing a significant autochthonous carbon input to the deeper anoxic layers in stratified water bodies. In addition, various algal species have been touted as promising candidates for anaerobic biogas production from biomass. Surprisingly, in spite of its ecological and economic relevance, the microbial community involved in algal detritus turnover under anaerobic conditions remains largely unexplored.ResultsHere, we characterized the microbial communities mediating the degradation of Chlorella vulgaris (Chlorophyta), Chara sp. strain IWP1 (Charophyceae), and kelp Ascophyllum nodosum (phylum Phaeophyceae), using sediments from an anaerobic spring (Zodlteone spring, OK; ZDT), sludge from a secondary digester in a local wastewater treatment plant (Stillwater, OK; WWT), and deeper anoxic layers from a seasonally stratified lake (Grand Lake O’ the Cherokees, OK; GL) as inoculum sources. Within all enrichments, the majority of algal biomass was metabolized within 13–16 weeks, and the process was accompanied by an increase in cell numbers and a decrease in community diversity. Community surveys based on the V4 region of the 16S rRNA gene identified different lineages belonging to the phyla Bacteroidetes, Proteobacteria (alpha, delta, gamma, and epsilon classes), Spirochaetes, and Firmicutes that were selectively abundant under various substrate and inoculum conditions. Within all kelp enrichments, the microbial communities structures at the conclusion of the experiment were highly similar regardless of the enrichment source, and were dominated by the genus Clostridium, or family Veillonellaceae within the Firmicutes. In all other enrichments the final microbial community was dependent on the inoculum source, rather than the type of algae utilized as substrate. Lineages enriched included the uncultured groups VadinBC27 and WCHB1-69 within the Bacteroidetes, genus Spirochaeta and the uncultured group SHA-4 within Spirochaetes, Ruminococcaceae, Lachnospiraceae, Yongiibacter, Geosporobacter, and Acidaminobacter within the Firmicutes, and genera Kluyvera, Pantoea, Edwardsiella and Aeromonas, and Buttiauxella within the Gamma-Proteobaceteria order Enterobacteriales.ConclusionsOur results represent the first systematic survey of microbial communities mediating turnover of algal biomass under anaerobic conditions, and highlights the diversity of lineages putatively involved in the degradation process.

Wide distribution of airborne ice-nucleation active Pseudomonas syringae in agricultural environments.

Pseudomonas syringae, a phytopathogen with a wide host range, inhabits various environments. Among these habitats, air is an important transport environment for microbes, allowing them to disperse over long distances; however, information on the distribution and composition of airborne P. syringae is limited. Here, we report the isolation of several groups of airborne P. syringae in Japan. Since 2013, we have trapped 43 strains of airborne P. syringae species complex, most of which were ice-nucleation active (INA), suggesting an important role for INA in atmospheric environments. Airborne P. syringae were isolated mainly between March and May, when the temperature is optimal for the epiphytic growth of P. syringae strains, indicates that plants are the main sources for airborne INA P. syringae. Multilocus sequence typing analyses categorized these strains into six clades. The most abundant clade, KID0033, clustered with strain UMAF0158, a pathogen of mango isolated in Spain, and Cit7, isolated in the USA. The second most abundant clade, KID0001, did not clustered with any pathovar or environmental strain reported previously. In addition, we isolated 14 P. syringae strains belonging to these two clades from asymptomatic and symptomatic leaves of kiwifruit, okra, and tea from different sites over the past decade. These strains are less virulent on originally isolated plants and other plant species under our inoculum conditions. These data indicate that certain groups of INA P. syringae, which were not previously recognized as pathogens, exist both in the air and on plants, and may be quite common throughout the world.

Enrichment of Secondary Wastewater Sludge for Production of Hydrogen from Crude Glycerol and Comparative Evaluation of Mono-, Co- and Mixed-Culture Systems.

Anaerobic digestion using mixed-culture with broader choice of pretreatments for hydrogen (H2) production was investigated. Pretreatment of wastewater sludge by five methods, such as heat, acid, base, microwave and chloroform was conducted using crude glycerol (CG) as substrate. Results for heat treatment (100 °C for 15 min) showed the highest H2 production across the pretreatment methods with 15.18 ± 0.26 mmol/L of medium at 30 °C in absence of complex media and nutrient solution. The heat-pretreated inoculum eliminated H2 consuming bacteria and produced twice as much as H2 as compared to other pretreatment methods. The fermentation conditions, such as CG concentration (1.23 to 24 g/L), percentage of inoculum size (InS) (1.23% to 24% v/v) along with initial pH (2.98 to 8.02) was tested using central composite design (CCD) with H2 production as response parameter. The maximum H2 production of 29.43 ± 0.71 mmol/L obtained at optimum conditions of 20 g/L CG, 20% InS and pH 7. Symbiotic correlation of pH over CG and InS had a significant (p-value: 0.0011) contribution to H2 production. The mixed-culture possessed better natural acclimatization activity for degrading CG, at substrate inhibition concentration and provided efficient inoculum conditions in comparison to mono- and co-culture systems. The heat pretreatment step used across mixed-culture system is simple, cheap and industrially applicable in comparison to mono-/co-culture systems for H2 production.

Impact of pH control and heat pre-treatment of seed inoculum in dark H2 fermentation: A feasibility report using mixed microalgae biomass as feedstock

This study investigated the effect of controlling pH (5.5) and heat pre-treatment of seed inoculum in dark fermentative hydrogen production. The results showed that only inoculum source plays an important role rather than pH and heat treatment. Seed source is vital factor despite, heat treatment and pH controlled at 5.5. Mesophilic fermentation resulted in CH4 generation, however, thermophilic fermentation while using thermophilic inoculum is opted for H2 generation. In contrast promoted mesophilic inoculum (mesophilic to thermophilic) still documented for CH4 generation. Peak hydrogen production rate (HPR) and methane production rate (MPR) were noted as 90 and 117 mL/L-d, during the conditions of thermo inoculum (thermophilic, pH 5.5) and pH no control (mesophilic) experiments, respectively. Peak, total solids (TS) and chemical oxygen demand (COD) removal were achieved as 56 and 42% at mesophilic condition. Volatile fatty acid (VFA) profiling revealed the background of the process performances. Microbial community analysis via fluorescent in-situ hybridization (FISH) narrated that bacteria and archaea communities were enriched during thermophilic and mesophilic experiments, respectively. Besides, the presence of methanogens revealed that heat treatment and controlling moderately acidic pH (5.5) could not completely eliminate them and resulted in CH4 generation, rather than H2 production.

Simultaneous Removal of Phenol and Dissolved Solids from Wastewater Using Multichambered Microbial Desalination Cell.

Microbial desalination cell (MDC) has great potential toward direct electricity generation from wastewater and concurrent desalination through potential difference developed due to microbial activity. Degradation of phenol by isolate Pseudomonas aeruginosa in anodic chamber and simultaneous desalination of water in middle desalination chamber of multichamber MDC is demonstrated in this study. Performance of the MDCs with different anodic inoculum conditions, namely pure culture of P. aeruginosa (MDC-1), 50% v/v mixture of P. aeruginosa and anaerobic mixed consortia (MDC-2) and anaerobic mixed consortia (MDC-3), was evaluated to compare the phenol degradation in anodic chamber, bioelectricity generation, and simultaneous total dissolved solids (TDS) removal from saline water in desalination chamber. Synergistic effect between P. aeruginosa and mixed anaerobic consortia as inoculum was evident in MDC-2 demonstrating phenol degradation of 90%, TDS removal of 75% in 72h of reaction time along with higher power generation of 27.5mW/m(2) as compared to MDC-1 (95%, 64%, 12.8mW/m(2), respectively) and MDC-3 (58%, 52%, 4.8mW/m(2), respectively). The results illustrate that the multichamber MDC-2 is effective for simultaneous removal of phenol and dissolved solids contained in industrial wastewaters.

In vitro phenotypic differentiation towards commensal and pathogenic oral biofilms

Commensal oral biofilms, defined by the absence of pathology-related phenotypes, are ubiquitously present. In contrast to pathological biofilms commensal biofilms are rarely studied. Here, the effect of the initial inoculum and subsequent growth conditions on in vitro oral biofilms was studied. Biofilms were inoculated with saliva and grown anaerobically for up to 21 days in McBain medium with or without fetal calf serum (FCS) or sucrose. Pathology-related phenotypes were quantified and the community composition was determined. Biofilms inoculated with pooled saliva or individual inocula were similar. Denaturing gradient gel electrophoresis (DGGE) analysis allowed differentiation of biofilms grown with sucrose, but not with FCS. Lactate production by biofilms was significantly increased by sucrose and protease activity by FCS. McBain grown biofilms showed low activity for both phenotypes. Three clinically relevant in vitro biofilm models were developed and could be differentiated based on pathology-related phenotypes but not DGGE analysis. These models allow analysis of health-to-disease shifts and the effectiveness of prevention measures.

A strain-independent method to induce progressive and lethal pneumococcal pneumonia in neutropenic mice.

BackgroundExperimental models of pneumonia with penicillin non-susceptible Streptococcus pneumoniae (PNSSP) are hard to reproduce because the majority of strains with clinical relevance (like serotypes 6B, 9 V and 19 F) have low murine virulence. By optimization of culture and inoculum conditions of PNSSP (using porcine mucin), our aim was to develop a suitable, reliable and reproducible pneumonia mouse model for anti-infective pharmacology research.ResultsSeven PNSSP strains, including serotypes 6B, 9 V, 14 and 19 F were included. Strain INS-E611 displayed the highest murine virulence and was chosen to validate the lung model. Nose-instilled pneumococci grew between 2.1 and 2.5 log10 CFU/g of lung in 24 hours when an optimized culture of bacterial cells was used, but animals were all alive and recovered of infection after 36 h. In contrast, inoculum supplementation with mucin led to 100% mortality related to a successful lung infection confirmed by histopathology. These findings were reproduced with all seven PNSSP strains in neutropenic mice. Immunocompetent animals cleared all strains spontaneously.ConclusionsThis pneumonia model produces a progressive and uniformly fatal lung infection with diverse serotypes of PNSSP independently of their intrinsic murine virulence.

New steady-state microbial community compositions and process performances in biogas reactors induced by temperature disturbances.

BackgroundThe microbial community in a biogas reactor greatly influences the process performance. However, only the effects of deterministic factors (such as temperature and hydraulic retention time (HRT)) on the microbial community and performance have been investigated in biogas reactors. Little is known about the manner in which stochastic factors (for example, stochastic birth, death, colonization, and extinction) and disturbance affect the stable-state microbial community and reactor performances.ResultsIn the present study, three replicate biogas reactors treating cattle manure were run to examine the role of stochastic factors and disturbance in shaping microbial communities. In the triplicate biogas reactors with the same inoculum and operational conditions, similar process performances and microbial community profiles were observed under steady-state conditions. This indicated that stochastic factors had a minor role in shaping the profile of the microbial community composition and activity in biogas reactors. On the contrary, temperature disturbance was found to play an important role in the microbial community composition as well as process performance for biogas reactors. Although three different temperature disturbances were applied to each biogas reactor, the increased methane yields (around 10% higher) and decreased volatile fatty acids (VFAs) concentrations at steady state were found in all three reactors after the temperature disturbances. After the temperature disturbance, the biogas reactors were brought back to the original operational conditions; however, new steady-state microbial community profiles were observed in all the biogas reactors.ConclusionsThe present study demonstrated that temperature disturbance, but not stochastic factors, played an important role in shaping the profile of the microbial community composition and activity in biogas reactors. New steady-state microbial community profiles and reactor performances were observed in all the biogas reactors after the temperature disturbance.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-014-0182-y) contains supplementary material, which is available to authorized users.

Ocean bacteria: performance on CODCr and NH4(+)-N removal in landfill leachate treatment.

An experiment was carried out to investigate the performance of mixed ocean bacteria, isolated from the ocean sediment, on landfill leachate treatment. In this treatment, ocean bacteria were the only constituent added to remove organics and NH(4)(+)-N. Given their considerable influence on wastewater purification, factors such as inoculum, initial pH, processing time and oxygen condition, were directly involved in this research. As indicated by laboratory test results, chemical oxygen demand (CODCr) and NH(4)(+)-N removal could reach 94.45% and 67.87%, respectively, after 3 days of treatment, in conditions of natural pH 6.3 and with the application of oxygen. The volt-ampere characteristics of the bacteria solution verified the redox-active ability of the bacteria in landfill leachate treatment.

Improvement of ε-poly-L-lysine production through seed stage development based on in situ pH monitoring.

Nissin, natamycin, and ε-poly-L-lysine (ε-PL) are three safe, microbial-produced food preservatives used today in the food industry. However, current industrial production of ε-PL is only performed in several countries. In order to realize large-scale ε-PL production by fermentation, the effects of seed stage on cell growth and ε-PL production were investigated by monitoring of pH in situ in a 5-L laboratory-scale fermenter. A significant increase in ε-PL production in fed-batch fermentation by Streptomyces sp. M-Z18 was achieved, at 48.9g/L, through the optimization of several factors associated with seed stage, including spore pretreatment, inoculum age, and inoculum level. Compared with conventional fermentation approaches using 24-h-old shake-flask seed broth as inoculum, the maximum ε-PL concentration and productivity were enhanced by 32.3 and 36.6%, respectively. The effect of optimized inoculum conditions on ε-PL production on a large scale was evaluated using a 50-L pilot-scale fermenter, attaining a maximum ε-PL production of 36.22g/L in fed-batch fermentation, constituting the first report of ε-PL production at pilot scale. These results will be helpful for efficient ε-PL production by Streptomyces at pilot and plant scales.

Performance Evaluation of a Bubble Column Photobioreactor for Carbon Dioxide Sequestration by Chlorella vulgaris

Biosequestration of carbon dioxide is a promising technique for global warming reduction. The present work evaluates the performance of a bubble column photobioreactor for simulated industrial effluent treatment using Chlorella vulgaris. C. vulgaris was cultivated under various conditions of initial size inoculum and initial carbon dioxide feed percentages. The maximum growth rate constant achieved was equal to 0.056 h−1 for the culture of an initial size of 0.01 g/L fed with 10% CO2. The mass of carbon fixed as a per cent of carbon sequestered was calculated for all cultures, and a maximum value of 40% was calculated for the culture of an initial size of 0.1 g/L fed with 5% CO2, indicating that not all carbon sequestered by the reactor is effectively fixed in biomass cells. The energy output (calculated as the higher heating value of produces biomass) as a per cent of light energy input was calculated to account for the energetic performance of the reactor, and the maximum calculated per cent was equal to 12.21% achieved for the culture of an initial size of 0.1 g/L fed with 5% CO2. Biomass subjected to a 16:8 and a 12:12 light/dark cycle yielded carbon fixation rate, which represents 86 and 18.8% of that obtained under continuous illumination respectively.

Inoculation of drought-stressed strawberry with a mixed inoculum of two arbuscular mycorrhizal fungi: effects on population dynamics of fungal species in roots and consequential plant tolerance to water deficiency.

The effect of inoculation with two arbuscular mycorrhizal fungi (AMF) on growth and drought tolerance of cultivated strawberry (Fragaria × ananassa) was studied. Three treatments (a single treatment either of Funneliformis mosseae BEG25, Funneliformis geosporus BEG11 or a 50:50 mixed inoculation treatment of both species) were compared to uninoculated plants. Species-specific primers for qPCR quantification of F. geosporus and F. mosseae DNA were developed to quantify the relative abundance of each fungus in roots of strawberry under different conditions of water stress. Co-occupation of the same root by both species was shown to commonly occur, but their relative abundance varied with water stress (reduced irrigation of up to 40%). Greater root colonisation was observed microscopically under water stress, but this increased colonisation was often accompanied with decreased amounts of fungal DNA in the root. F. mosseae tended to become more abundant under water stress relative to F. geosporus. There was significant correlation in the fungal colonisation measurements from the microscopic and qPCR methods under some conditions, but the nature of this relationship varied greatly with AMF inoculum and abiotic conditions. Single-species inoculation treatments gave similar benefits to the host to the mixed inoculation treatment regardless of irrigation regime; here, amount of colonisation was of greater importance than functional diversity. The addition of AMF inocula to plants subjected to reduced irrigation restored plant growth to the same or higher values as the non-mycorrhizal, fully-watered plants. The water use efficiency of plants was greater under the regulated deficit irrigation (RDI) regime and in AMF-inoculated plants, but there were no significant differences between plants inoculated with the single or combined inoculum. This study demonstrated that the increase in plant growth was directly influenced by an increase in root colonisation by AMF when individual plants were examined.

Bioproduction of Conjugated Linoleic Acid in Yogurt by Probiotic Bacteria

Conjugated linoleic acid as unique fatty acid of milk fat has beneficial properties including antioxidant‚ anticarcinogen‚ antidiabetic‚ antiblood pressure‚ stimulating the body immune system and reducing cholesterol. The aim of this study was assessing ability of some probiotics for biotransformation of linoleic acid to conjugated linoleic acid. Effect of process variables were investigated on production of conjugated linoleic acid in probiotic yogurt. An 8 run Plackett-Burman design was used to study the effect of 7 variables included: addition of supplements (whey powder‚ the amount of added grape seed oil), fermentation (temperature, pH, incubation time) and inoculum condition (age and size) on biomass and conjugated linoleic acid production in probiotic yogurt containing strains of Lactobacillus acidophilus La5, Bifidobacterium bifidum and Propionibacterium freudenerchii grown in medium containing free linoleic acid. The highest amount of conjugated linoleic acid was obtained by addition of 8% w/v whey powder, addition of 4%v/v grape seed oil in pH=6.0, inoculation of 0.7%v/v Inoculum of 36 h age and fermentation at temperature of 35°C for 27 h. This research showed that at the optimized conditions‚ the amount of conjugated linoleic acid in probiotic yogurt was increased by 40% from an average of 8.01 mg/g fat in non-treated yogurt to 11.03 mg/g fat of probiotic yogurt containing grape seed oil.

Uncoupling of Bacterial and Terrigenous Dissolved Organic Matter Dynamics in Decomposition Experiments

The biodegradability of terrigenous dissolved organic matter (tDOM) exported to the sea has a major impact on the global carbon cycle, but our understanding of tDOM bioavailability is fragmentary. In this study, the effects of preparative tDOM isolation on microbial decomposition were investigated in incubation experiments consisting of mesocosms containing mesohaline water from the Baltic Sea. Dissolved organic carbon (DOC) consumption, molecular DOM composition, bacterial activities, and shifts in bacterial community structure were compared between mesocosms supplemented with riverine tDOM, either as filtered, particle-free river water or as a concentrate obtained by lyophilization/tangential ultrafiltration, and those containing only Baltic Sea water or river water. As shown using ultra-high-resolution mass spectrometry (15 Tesla Fourier-transform ion cyclotron resonance mass spectrometry, FT-ICR-MS) covering approximately 4600 different DOM compounds, the three DOM preparation protocols resulted in distinct patterns of molecular DOM composition. However, despite DOC losses of 4–16% and considerable bacterial production, there was no significant change in DOM composition during the 28-day experiment. Moreover, tDOM addition affected neither DOC degradation nor bacterial dynamics significantly, regardless of the tDOM preparation. This result suggested that the introduced tDOM was largely not bioavailable, at least on the temporal scale of our experiment, and that the observed bacterial activity and DOC decomposition mainly reflected the degradation of unknown, labile, colloidal and low-molecular weight DOM, both of which escape the analytical window of FT-ICR-MS. In contrast to the different tDOM preparations, the initial bacterial inoculum and batch culture conditions determined bacterial community succession and superseded the effects of tDOM addition. The uncoupling of tDOM and bacterial dynamics suggests that mesohaline bacterial communities cannot efficiently utilize tDOM and that in subarctic estuaries other factors are responsible for the removal of imported tDOM.

Optimized fermentation conditions for improved antibody yield in hybridoma cells

Background Traditionally antibody producing cells like hybridoma cells sank into oblivion since other suspension cell lines have captured the biopharmaceutical production market. However, they are still of particular interest in academic and industrial diagnostic research. Hence, fast and sufficient antibody production is needed as proof of concept, for toxicology and in vivo studies. Although, hybridoma cultivation in fetal bovine serum (FBS) containing animal derived ingredients, like contaminating IgG, is undesirable and leads to difficulties in purification. When reducing the serum to a minimum other key components of the FBS have to be replaced. Therefore, human insulinlike growth factor (IGF) [1] and the surfactant Pluronic F68 were supplemented to improve overall cell performance and to reduce shear stress during shaking respectively employing Design of Experiment (DoE)[2]. Compared to the original basal medium an improvement in cell growth, viability and antibody titer was achieved. These optimized inoculum conditions were used for subsequent bioreactor fermentations. Furthermore, these conditions were used in order to test feeding strategies. For this purpose a fed-batch process with a double bolus feed was simulated in shake flasks with two different glucose feeding strategies with and without Hyclone Cell Boost 6 (CB6). Finally, the result from shake flasks could be verified and improved antibody yield was achieved in a controlled 2L fed-batch process.

The first engagement of partners in the Euprymna scolopes–Vibrio fischeri symbiosis is a two‐step process initiated by a few environmental symbiont cells

We studied the Euprymna scolopes-Vibrio fischeri symbiosis to characterize, in vivo and in real time, the transition between the bacterial partner's free-living and symbiotic life styles. Previous studies using high inocula demonstrated that environmental V. fischeri cells aggregate during a 3 h period in host-shed mucus along the light organ's superficial ciliated epithelia. Under lower inoculum conditions, similar to the levels of symbiont cells in the environment, this interaction induces haemocyte trafficking into these tissues. Here, in experiments simulating natural conditions, microscopy revealed that at 3 h following first exposure, only ∼ 5 V. fischeri cells aggregated on the organ surface. These cells associated with host cilia and induced haemocyte trafficking. Symbiont viability was essential and mutants defective in symbiosis initiation and/or production of certain surface features, including the Mam7 protein, which is implicated in host cell attachment of V. cholerae, associated normally with host cilia. Studies with exopolysaccharide mutants, which are defective in aggregation, suggest a two-step process of V. fischeri cell engagement: association with host cilia followed by aggregation, i.e. host cell-symbiont interaction with subsequent symbiont-symbiont cell interaction. Taken together, these data provide a new model of early partner engagement, a complex model of host-symbiont interaction with exquisite sensitivity.

In Vitro Activity of Daptomycin against Enterococcus faecalis under Various Conditions of Growth-Phases, Inoculum and pH

Enterococcus faecalis (E. faecalis) has become a major leading cause of nosocomial endocarditis. Treatment of such infections remains problematic and new therapeutic options are needed. Nine E. faecalis strains were tested: six obtained from patients presenting endocarditis, one with isolated bacteremia, and two reference strains. Antibiotics included daptomycin, alone or in combination, linezolid, tigecycline, rifampicin, gentamicin, teicoplanin, ceftriaxone and amoxicillin. Time-kill studies included colony counts at 1, 4 and 24 h of incubation. Significant bactericidal activity was defined as a decrease of ≥3log10CFU/ml after 24 h of incubation. Antibiotics were tested at a low (106 CFU/ml) and high (109 CFU/ml) inoculum, against exponential- and stationary-phase bacteria. We also performed time kill studies of chemically growth arrested E. faecalis. Various pH conditions were used during the tests. In exponential growth phase and with a low inoculum, daptomycin alone at 60 µg/ml and the combination amoxicillin-gentamicin both achieved a 4-log10 reduction in one hour on all strains. In exponential growth phase with a high inoculum, daptomycin alone was bactericidal at a concentration of 120 µg/ml. All the combinations tested with this drug were indifferent. In stationary phase with a high inoculum daptomycin remained bactericidal but exhibited a pH dependent activity and slower kill rates. All combinations that did not include daptomycin were not bactericidal in conditions of high inoculum, whatever the growth phase. The results indicate that daptomycin is the only antibiotic that may be able of overcoming the effects of growth phase and high inoculum.

Impact of Bispyribac-sodium Application on Annual Bluegrass Control and Brown Patch Severity in Tall Fescue

Annual bluegrass (Poa annua L.) is a problematic weed in tall fescue [Festuca arundinacea (Schreb.) S.J. Darbyshire], with limited options available for postemergence control. Field research was conducted to evaluate bispyribac-sodium application rates (37 or 74 g ai·ha−1) (0.033 or 0.066 lb ai·A−1) and timings (March, April or May) as well as iron supplementation on brown patch (Rhizoctonia solani) severity, annual bluegrass control, and tall fescue quality. In general, applying bispyribac-sodium to tall fescue did not result in significantly more brown patch than in untreated plots in field trials. Applying bispyribac-sodium in March or April resulted in significantly higher annual bluegrass control than applications in May. In greenhouse experiments, bispyribac-sodium at 37 and 74 g ai·ha−1 (0.033 or 0.066 lb ai·A−1) was applied to brown patch-inoculated tall fescue plants. Under conditions of high inoculum and humidity in those greenhouse studies, applications of bispyribac-sodium increased the number of brown patch lesions relative to untreated plants. Tall fescue plant height was initially reduced after being treated with bispyribac-sodium; however, six weeks after application tall fescue plants in treated with herbicide were taller than the nontreated plants.

Antifungal activity of Meyerozyma guilliermondii: Identification of active compounds synthesized during dough fermentation and their effect on long-term storage of wheat bread

Preliminarily, 146 strains of yeasts were screened for the antifungal activity toward the indicator Penicillium roqueforti DPPMAF1. The strain Meyerozyma guilliermondii LCF1353 was selected and used for dough fermentation. The water/salt soluble extract of the dough was analyzed by HPLC and GC/MS-SPME. The synthesis of the extracellular cell wall-degrading enzyme β-1,3-glucanase and ethyl-acetate was shown. The effect on conidia germination mainly suggested a fungistatic activity. M. guilliermondii LCF1353 was used as starter for dough fermentation in combination with Wickeramomyces anomalus 1695 and Lactobacillus plantarum 1A7, which were previously selected for antifungal activity. The growth of the strains was monitored by plate count and molecular techniques, and competitive or antagonistic interactions among them were excluded. Bread started with the combination of M. guilliermondii LCF1353, W. anomalus LCF1695 and L. plantarum 1A7 showed a more prolonged shelf life compared to the other breads. Fungal growth was delayed at least until 14 days of storage, under conditions of high artificial inoculum. The bread manufactured with the above combination showed good chemical and textural characteristics and, as shown by sensory analysis, it was appreciated for elasticity, color and taste.