Broth Filtrate Research Articles

Plant Growth Promotion and Biological Control against Rhizoctonia solani in Thai Local Rice Variety "Chor Khing" Using Trichoderma breve Z2-03.

Several strains of Trichoderma are applied in the field to control plant diseases due to their capacity to suppress fungal pathogens and control plant diseases. Some Trichoderma strains also are able to promote plant growth through the production of indole-3-acetic acid (IAA). In southern Thailand, the local rice variety "Chor Khing" is mainly cultivated in the Songkhla province; it is characterized by slow growth and is susceptible to sheath blight caused by Rhizoctonia solani. Therefore, this research aimed to screen Trichoderma species with the ability to promote plant growth in this rice variety and enact biological control against R. solani. A total of 21 Trichoderma isolates were screened for indole compound production using the Salkowski reagent. The Z2-03 isolate reacted positively to the Salkowski reagent, indicating the production of the indole compound. High-performance liquid chromatography (HPCL) confirmed that Z2-03 produced IAA at 35.58 ± 7.60 μg/mL. The cell-free culture filtrate of the potato dextrose broth (CF) of Z2-03 induced rice germination in rice seeds, yielding root and shoot lengths in cell-free CF-treated rice that were significantly higher than those of the control (distilled water and culture broth alone). Furthermore, inoculation with Trichoderma conidia promoted rice growth and induced a defense response against R. solani during the seedling stage. Trichoderma Z2-03 displayed an antifungal capacity against R. solani, achieving 74.17% inhibition (as measured through dual culture assay) and the production of siderophores on the CAS medium. The pot experiment revealed that inoculation with the Trichoderma sp. Z2-03 conidial suspension increased the number of tillers and the plant height in the "Chor Khing" rice variety, and suppressed the percentage of disease incidence (PDI). The Trichoderma isolate Z2-03 was identified, based on the morphology and molecular properties of ITS, translation elongation factor 1-alpha (tef1-α), and RNA polymerase 2 (rpb2), as Trichoderma breve Z2-03. Our results reveal the ability of T. breve Z2-03 to act as a plant growth promoter, enhancing growth and development in the "Chor Khing" rice variety, as well as a biological control agent through its competition and defense induction mechanism in this rice variety.

Anti-fouling tight ultrafiltration membrane for gastrodin purification

The issues of flux decline and irreversible membrane fouling must be considered in membrane separation. In this paper, the culture medium, bacterial cells, and proteins were removed using a one-step tight ultrafiltration (UF) membrane separation process. Although the membrane resistance of the tight UF membranes increased owing to their smaller pore size, the stable flux of the 6 nm membrane during fermentation broth filtration of gastrodin was 28.0% higher than that of loose UF membranes, and the flux recovery ratio reached 97.3%. During purification, a higher filtration flux was obtained by retaining the operating pressure within the range of 2–3 bar and the operating temperature range of 50–60 °C. The average flux of a 6 nm 19-channel membrane reached 56 L·m−2·h−1, and the total yield of gastrodin reached 96.2%. This study provides a basis for the large-scale application of tight UF membrane in food industry.

Biomass conversion through optimization of cellulase from Chryseobacterium junjuense Bp17 and their utility in bioethanol production

The search for economically viable and less laborous strategy for bioethanol production has increased globally in this quest bacterial cellulase treated biomass has been promising. Potential bacterium isolated from the forest soil near Bandipur of Karnataka, India exploiting its cellulolytic activity on the CMC agar medium. Molecular identification and characterization of isolate Bp17 revealed as Chryseobacterium junjuense Bp17. An optimization study, enhance the yield of the enzyme through varying parameters such as time, temperature, and pH. Enzymatic assays like β 1, 4 endoglucanase (148.55 U/ml), β 1, 4 exoglucanase (37.21 U/ml), and β glucosidase (42.21 U/ml) exhibit the enzyme activity. Endo, exo and β-glucosidase activities of hydrolyzed biomass broth like coconut husk; 212.88 ± 1.24 U/ml, 151.65 ± 1.24 U/ml and 176.63 ± 1.24 U/ml, rice bran; 223.72 ± 1.42 U/ml, 112.88 ± 1.42 U/ml and 133.43 ± 1.42 U/ml, Pongamia leaves; 389.69 ± 2.54 U/ml, 205.92 ± 2.54 and 187.99 ± 2.54 U/ml, and wood waste; 196.86 ± 0.2 U/ml, 138.90 ± 0.2 U/ml and 168.84 ± 0.2 U/ml, respectively. Hydrolyzed and control biomass differences analyzed through Scanning electron microscope (SEM), Energy dispersive X-ray (EDX), and Fourier transform infrared (FTIR) spectroscopy. Zymography reveals the activity and molecular weight of cellulolytic enzymes (40-130 KB). Hydrolyzed broth filtrate produced from biomass used as crude enzyme and further used for bioethanol production through the yeast fermentation process.

Comparison of ceramic microfiltration and ultrafiltration membranes for the clarification of simulated sebacic acid fermentation broth

Sebacic acid, an important chemical intermediate, is usually prepared by fermentation. However, the composition of the fermentation broth is complex, which causes significant difficulties in the purification of the product and is still a key problem in the industry. In this study, the application of ceramic membranes for the separation and purification of simulated fermentation broth was studied. Ceramic microfiltration (MF) and ultrafiltration (UF) membranes with average pore sizes of 100 and 6 nm, respectively, were systematically compared by analyzing their separation effects on different components in the fermentation broth and their permeation flux during filtration. Both ceramic MF and UF membranes can be used to clarify the fermentation broth with turbidity less than 0.01 NTU by the effective removal of emulsified oil and bacteria while allowing sodium sebacate to pass through freely. However, the ceramic UF membrane showed a higher protein rejection of more than 95%, whereas the removal rate of the MF membrane was only approximately 20%. In addition, the fouling process of ceramic UF membrane was analyzed. In the suitable operating conditions when the pH was 9.2, the temperature was 60 ℃, the pressure was 0.1 MPa and the cross-flow velocity was 1.8 m·s−1, the membrane fouling process was dominated by the reversible cake formation. A ceramic UF membrane with a smaller pore size can effectively avoid pollution in pore channels, and thus exhibits a higher permeation flux in the filtration of the fermentation broth.

Single‐use centrifugal separator enables intensification of the clarification process in biomanufacturing of recombinant proteins

AbstractBACKGROUNDThe need to produce more biologics at lower costs and hence intensify bioprocessing has significantly improved upstream productivity (cell culture titers ≥3 g L−1 and cell densities ≥20 × 106 cells mL−1), shifting the economic and production bottleneck to downstream manufacturing. The first downstream unit operation is the clarification of the cell culture broth to remove various insoluble (such as cells and cell debris) and soluble (such as host cell DNA and proteins) contaminants, producing a feed stream suitable for further downstream purification. The high cell‐density cultures obtained in modern intensified bioprocessing have made legacy single‐use clarification trains (based primarily on depth filtration of the cell culture broth) ineffective and impractical, significantly increasing the economic and material burden of the clarification process.RESULTSWe have developed and characterized approaches that enable intensification of the clarification operation, by increasing process capacities while reducing material requirements and footprint, for single‐use manufacturing facilities. These approaches are based on primary clarification using the Alfa Laval CultureOne™ centrifuge (a continuous solid discharge disc‐stack centrifuge with a single‐use flow path) followed by secondary clarification using single‐use disposable depth filters. We show that these intensified clarification trains are suitable for processing high cell‐density cultures (6–12% packed cell volume) with significantly high yields (≥90%) and impurity clearance, along with reduced operating costs (30–60% savings).CONCLUSIONIncorporating a single‐use continuous discharge centrifuge into the clarification train enables clarification of high cell‐density cultures in single‐use manufacturing facilities and enhances process economic and environmental sustainability. © 2023 Society of Chemical Industry (SCI).

ANTIMICROBIAL AND PHYTOCHEMICAL SCREENING OF EXTRACTS PRODUCED BY ENDOPHYTIC FUNGI ISOLATED FROM THE ROOT OF Lawsonia inermis ANTIMICROBIAL AND PHYTOCHEMICAL SCREENING OF EXTRACTS PRODUCED BY ENDOPHYTIC FUNGI ISOLATED FROM THE ROOT OF Lawsonia inermis

Endophytic fungi produced a secondary metabolite similar to their host plant; therefore it can be used as a source of producing active metabolites which lead in drug discoveries. The present study evaluate the antimicrobial activity of endophytic fungi from Lawsonia inermis and isolation of bioactive compounds for new antimicrobial agent. Fresh plant root materials were used for the isolation process, Aspergillus niger was identified as the species present on the plant. The screening of fungal for biological active secondary metabolites was carried out on malt broth fermentation. The broth filtrate was extracted with ethyl acetate and partitioned using a separating funnel. Disc diffusion methods of an antimicrobial sensitivity test at 100μg/disc, 50μg/disc, 25μg/disc 12.5μg/disc was adopted in testing the bioactivity of the extract against two clinical bacterial isolates of staphylococcus Aureus, Escheria coli and two clinical fungal isolates of Candida Albican and Aspergillus Flavus using disc diffution techniques. The extract were further subjected to phytochemical screening to detect the presence of secondary metabolites using standard procedures. The sensitivity test results showed that all the tested isolates are sensitive to extract at 12.5µg/disc as follows: Staphylococcus Aureus (10mm) , Escheria coli (11mm) , Candida Albican (7mm) and Aspergillus Flavus (8mm) . The result of phytochemical screening indicates the presence of alkaloids, cardical glycosides ,resins , saponins ,tannins , triterpenoids .The bioassay from the ethyl acecate fraction (HR) of the metabolite using column chromatography ,lead to the isolation of three pure compounds. The results of the antimicrobial activity of the isolated compounds indicated that (HR-102) was more potent against candida albican (11mm) at 12.5μg/disc followed by staphylococcus aureus (10mm) at 12.5μg/disc, escheria coli (9mm) at 12.5μg/disc, aspergillus flavus (8mm) at 12.5μg/disc. This signifies the potency for the development of therapeutic agent against pathogenic microorganisms. phytochemical screening of the three extracts fraction revealed the presence of alkaloids , steroids ,resins , triterpenoids .

Novel hyperthermophilic crenarchaeon Infirmifilum lucidum gen. nov. sp. nov., reclassification of Thermofilum uzonense as Infirmifilum uzonense comb. nov. and assignment of the family Thermofilaceae to the order Thermofilales ord. nov.

A novel hyperthermophilic crenarchaeon, strain 3507LTT, was isolated from a terrestrial hot spring near Tinguiririca volcano, Chile. Cells were non-motile thin, slightly curved filamentous rods. It grew at 73–93 °C and pH range of 5 to 7.5 with an optimum at 85 °C and pH 6.0–6.7. The presence of culture broth filtrate of another hyperthemophilic archaeon as well as yeast extract was obligatory for growth of the novel isolate. Strain 3507LTT is an anaerobic chemoorganoheterotroph, fermenting monosaccharides, disaccharides and polysaccharides (lichenan, starch, xanthan gum, xyloglucan, alpha-cellulose and amorphous cellulose). No growth stimulation was detected when nitrate, thiosulfate, selenate or elemental sulfur were added as the electron acceptors. The complete genome of strain 3507LTT consisted of a single circular chromosome with size of 1.63 Mbp. The DNA G+C content was 53.9%. According to the 16S rRNA gene sequence as well as conserved protein sequences phylogenetic analyses, strain 3507LTT together with Thermofilum uzonense formed a separate cluster within a Thermofilaceae family (Thermoproteales/Thermoprotei/Crenarchaeota). Based on phenotypic characteristics, phylogeny as well as AAI comparisons, a novel genus and species Infirmifilum lucidum strain 3507LTT (=VKM B-3376T = KCTC 15797T) gen. nov. sp. nov. was proposed. Its closest relative, Thermofilum uzonense strain 1807–2T should be reclassified as Infirmifilum uzonense strain 1807–2T comb. nov. Finally, based on phylogenomic and comparative genome analyses of representatives of Thermofilaceae family and other representatives of Thermoproteales order, a proposal of transfer of the family Thermofilaceae into a separate order Thermofilales ord. nov. was made.

Influence of Ceramic Membrane Surface Characteristics on the Flux Behavior of a Complex Fermentation Broth.

The valorization of agro-industrial residues using yeasts as biocatalysts requires efficient methods for biomass separation. Filtration with ceramic membranes is suitable for this task, however, the challenge of flux decline and the unavoidable cleaning must be taken into account. We investigated the filtration of fermentation broth and its components using tubular microfiltration and ultrafiltration membranes, and hollow-fiber ultrafiltration membranes, with cut-offs of 30 and 200 nm. The steady-state flux was limited by fouling under comparable wall shear stress conditions but increased when the wall shear stress was higher. Single-component filtration with two 30 nm tubular ultrafiltration membranes, whose average surface roughness ranged from 1.0 to 3.9 µm, showed that smoother surfaces experience less biomass fouling under more intense hydrodynamic conditions. Furthermore, we showed experimentally and by scanning electron microscopy in filtration with 30 nm tubular membranes that the thickness of the first separation layer is responsible for the degree of irreversible resistance caused by the deposition of organic material in the membrane pores. The thickness of this layer should therefore be minimized without compromising mechanical stability.

Growth Inhibition of Phytopathogenic Fungi and Oomycetes by Basidiomycete Irpex lacteus and Identification of its Antimicrobial Extracellular Metabolites.

In dual culture confrontation assays, basidiomycete Irpex lacteus efficiently antagonized Fusarium spp., Colletotrichum spp., and Phytophthora spp. phytopathogenic strains, with growth inhibition percentages between 16.7–46.3%. Antibiosis assays evaluating the inhibitory effect of soluble extracellular metabolites indicated I. lacteus strain inhibited phytopathogens growth between 32.0–86.7%. Metabolites in the extracellular broth filtrate, identified by UPLC-QTOF mass spectrometer, included nine terpenes, two aldehydes, and derivatives of a polyketide, a quinazoline, and a xanthone, several of which had antifungal activity. I. lacteus strain and its extracellular metabolites might be valuable tools for phytopathogenic fungi and oomycete biocontrol of agricultural relevance.

Lachancea thermotolerans acts as a resistance inducer in soybean infected with Meloidogyne incognita

The worldwide interest in sustainable agriculture has contributed to the development of alternative methods for the control of plant pests and diseases. This study aimed to assess the efficiency of Lachancea thermotolerans CCMA 0763 and its metabolites in controlling Meloidogyne incognita in soybean and their effects on plant defense enzymes and glyceollin synthesis. The following treatments were applied as foliar spray 4 days before nematode inoculation: fermentation broth, broth filtrate, yeast cells, sugarcane juice, acibenzolar-S-methyl (ASM). An inoculated untreated control and an absolute control were also included. The same treatments were used in the glyceollin assay. For analysis of resistance induction, the treatments were fermentation broth, broth filtrate, yeast cells, ASM, and water (control). Fermentation broth and yeast cells reduced total nematode number, population density and reproduction factor. Yeast-based treatments and ASM enhanced glyceollin synthesis compared with sugarcane juice and water. Peroxidase activity was highest at 4 and 10 days after treatment in plants treated with yeast-based treatmentss. Broth filtrate and yeast cells increased polyphenol oxidase activity at 4 days after treatment. Phenylalanine ammonia-lyase and glucanase activities were not influenced by treatment. L. thermotolerans stimulated phytoalexin synthesis in soybean cotyledons and defense enzyme activity in soybean roots, showing potential as a biopesticide.

Antimicrobial and antioxidant activities and chemical profiling of Curvularia tsudae endophytic in Cynodon dactylon (L.) Pers.

There is a growing body of evidence that endophytic fungal metabolites possess important biological activities. Cynodon dactylon (L.) Pers., a well-known grass species with potential medicinal properties, is under-explored for the diversity of endophytic fungal species and their metabolites. We report here the diversity of endophytic fungi in the culm, leaf and inflorescence of Cynodon dactylon when cultured on moist blotter (MB), potato dextrose agar (PDA) and malt extract agar (MEA). Species richness, Shannon and Simpson diversity and evenness indices showed that PDA followed by MEA supported the growth of the largest number of fungal species. Amongst four fungal species tested, Curvularia tsudae was selected for further studies on antimicrobial and antioxidant activities. The mycelial mat (MM) and culture filtrate (CF) of PD broth grown Curvularia tsudae extracted with ethyl acetate and methanol, respectively, were subjected to antimicrobial assay against five bacterial and four fungal test isolates. Results indicated that the ethyl acetate extract of CF had moderate activity against Enterococcus faecalis, Escherichia coli, Pseudomonas fluorescence and Staphylococcus aureus whereas the methanolic MM extract showed high to moderate activity to Aspergillus flavus, A. niger and Fusarium oxysporum. Cyclic voltammetric analysis of ethyl acetate extract showed very good antioxidant activity and the extract contained coumarins when determined by HPLC. High-resolution orbitrap LC-MS of ethyl acetate extract revealed the presence of metabolites with antimicrobial and antioxidant and other biological activities. Finding of the present study suggested that Curvularia tsudae could be exploited for pharmaceutical applications.

Determinación del potencial nematicida y nematostático in vitro de Pleurotus ostreatus (Jacq. ex Fr.) sobre larvas J2 de Globodera pallida (Stone)

Globodera pallida genera pérdidas de hasta el 30 % en el rendimiento cultivo de papa en el Ecuador. El control quí­mico de la plaga supone riesgos de toxicidad al suelo y para el agricultor. En este estudio se determinó el potencial nematicida y nematostático in vitro del micelio en agar agua y del filtrado del caldo de cultivo de Pleurotus ostreatus en medio Sabouraud sobre larvas J2 de G. pallida. En el efecto del micelio se observó un mayor porcentaje de nemátodos inmóviles (34 %) a las 24 horas de exposición, y el efecto nematicida más efectivo a las 72 horas, con una mortalidad del 80,3 %. No existió relación entre el porcentaje de J2 inmóviles, el tiempo de exposición y la concentración del filtrado en la actividad nematostática; sin embargo, el tratamiento con 100 % de concentrado y 8 h de exposición, dio como resultado un mayor porcentaje de nemátodos inmóviles (65,2 %). El efecto nematicida del filtrado a una concentración del 100 % y 24 horas de exposición, fue la más efectiva, con una tasa de mortalidad de larvas del 41,6 %. El micelio y el filtrado de P. ostreatus presentaron actividad nematostática y nematicida in vitro frente a larvas de G. pallida.

Effects of addition of elicitors on rimocidin biosynthesis in Streptomyces rimosus M527.

The polyene macrolide rimocidin, produced by Streptomyces rimosus M527, is highly effective against a broad range of fungal plant pathogens, but at low yields. Elicitation is an effective method of stimulating the yield of bioactive secondary metabolites. In this study, the biomass and filtrate of a culture broth of Escherichia coli JM109, Bacillus subtilis WB600, Saccharomyces cerevisiae, and Fusarium oxysporum f. sp. cucumerinum were employed as elicitors to promote rimocidin production in S. rimosus M527. Adding culture broth and biomass of S. cerevisiae (A3) and F. oxysporum f. sp. cucumerinum (B4) resulted in an increase of rimocidin production by 51.2% and 68.3% respectively compared with the production under normal conditions in 5-l fermentor. In addition, quantitative RT-PCR analysis revealed that the transcriptions of ten genes (rimA to rimK) located in the gene cluster involved in rimocidin biosynthesis in A3 or B4 elicitation experimental group were all higher than those of a control group. Using a β-glucuronidase (GUS) reporter system, GUS enzyme activity assay, and Western blot analysis, we discovered that elicitation of A3 or B4 increased protein synthesis in S. rimosus M527. These results demonstrate that the addition of elicitors is a useful approach to improve rimocidin production.Key Points • An effective strategy for enhancing rimocidin production in S. rimosus M527 is demonstrated. • Overproduction of rimocidin is a result of higher expressed structural genes followed by an increase in protein synthesis.

Optimization of the simultaneous production of cellulase and xylanase by submerged and solid-state fermentation of wheat chaff

Wheat chaff as an agricultural waste represents a cheap raw material for biotechnological processes. With its lignocellulosic composition, it is suitable for producing hydrolytic enzymes for second generation renewable fuel production technologies. The aim of this work was to optimize the process parameters (cultivation temperature 25?35?C, pH value 4?6 and cultivation time 3?7 days) of the cultivating fungi (Trichoderma reesei QM 9414) on a media based on wheat chaff by submerged and solid-state techniques, in order to enhance and compare the two types of simultaneous cellulase and xylanase production. Optimal conditions for the submerged fermentation were 29.65?C for temperature, pH 4.27 and 7 days of cultivation, while for the solid-state fermentation, the optimal conditions were 28.01?C, pH 6.00 and 7 days. The cellulolytic and xylanolytic activities of the obtained cultivation broth filtrates were 0.0535 and 0.1676 U mL-1 for the submerged fermentation, and 0.0407 and 0.1401 U mL-1 for the solid-state fermentation, respectively, and with a 26.77 and 13.39 % enhancement of enzyme activity for submerged fermentation, and a 22.96 and 42.66 % enhancement for solid-state fermentation, respectively, compared to the results obtained before optimization.

Improving α, ω-dodecanedioic acid productivity from n-dodecane and hydrolysate of Candida cells by membrane integrated repeated batch fermentation

The aim of the present study is to develop an effective production process for α, ω-dodecanedioic acid (DC12) biosynthesis using n-dodecane and hydrolysate of Candida cells as substrates by membrane integrated repeated batch fermentation. Cells and n-dodecane were simultaneously recycled during the filtration of fermentation broth (FB) with a 150 kDa ceramic membrane under a cross-flow velocity of 4 m/s and a trans-membrane pressure of 0.2 MPa, and it was also revealed that the cells in the broth could alleviate the membrane fouling during the FB filtration. Moreover, the hydrolysate of the collected cells could be successfully used as a nitrogen source to replace 50% yeast extract for decreasing the DC12 production cost. With repeated-batch culture in a membrane bioreactor, the maximal DC12 productivity could be enhanced by 57.8% compared with the batch culture, meanwhile n-dodecane and cells could be recovered and used for the next fermentation cycle.

Nematicidal activity of grammicin produced by Xylaria grammica KCTC 13121BP against Meloidogyne incognita.

The endolichenic fungus Xylaria grammica KCTC 13121BP showed strong nematicidal activity against Meloidogyne incognita. This study aimed to identify the nematicidal metabolites and to evaluate the efficacy of the strain as a biocontrol agent under pot and field conditions. Bioassay-guided fractionation and instrumental analyses led to grammicin being identified as the nematicidal metabolite. Because patulin is a mycotoxic isomer of grammicin and is known to have strong antibacterial and cytotoxic activities, several biological activities of the two compounds were compared. Grammicin showed strong second-stage juvenile killing and egg-hatching inhibitory effects, with a 50% effective concentration at 72 h (EC50/72 h ) of 15.9 µg/mL and a 50% effective concentration at 14 days (EC50/14 days ) of 5.87 µg/mL, respectively, whereas patulin was virtually inactive in both respects. Patulin was strongly active toward various phytopathogenic bacteria in vitro, whereas grammicin was weakly so. Patulin at the concentration range of 0.1-10 µg/mL also showed dose-dependent cytotoxicity toward the human first-trimester trophoblast cell line SW.71, whereas grammicin was not toxic toward this cell line. In pot and field experiments, a wettable powder-type formulation and fermentation broth filtrate of X. grammica KCTC 13121BP effectively suppressed the development of root-knot nematode disease on tomato and melon plants. The results suggest that X. grammica and grammicin may have potential applications for control of root-knot nematode disease of various crops. © 2017 Society of Chemical Industry.

ANTIOXIDANT ACTIVITIES OF MYCELIA AND BROTH FILTRATE EXTRACTS OF ASPERGILLUS SPP

The antioxidant activities of mycelia and broth filtrate ethyl acetate extracts produced from the cultures of 12 Aspergillus spp. were investigated. Extracts showed a concentration-dependent antioxidant activity by inhibiting DPPH radicals. Broth filtrate extracts showed higher activity than mycelia filtrate extracts. A. fumigatus showed the best activity (with 92.5% inhibition at the concentration of 0.8 mg ml-1). The extracts exhibited potent nitric oxide-scavenging activity. Broth filtrate extract of A. fumigatus showed the best activity (with 79.6 % inhibition at 1.6 mg ml-1) followed by the A. ostianus and A. terreus. Reducing powers of extracts also increased with the increases in their concentrations. Two broth filtrate extracts, A. terreus and A. fumigatus, have shown potent reducing power. In chelating ability, mycelia filtrate extracts showed higher activity. A. flavus showed the best activity (with 49.1% inhibition at 1.6 mg ml-1). The present study demonstrates the potential of soil fungi to have antioxidant activity similar to plants and represent them as new sources of natural antioxidants.

Rapid Phenotypic Detection of Microbial Resistance in Gram-Positive Bacteria by a Real-Time Laser Scattering Method.

We developed a methodology for antimicrobial susceptibility testing (AST) based on the BacterioScanTM216R laser scattering technology, using methicillin resistance in Staphylococcus aureus and vancomycin resistance in enterococci as exemplar for important resistance phenotypes. Fifty methicillin-resistant (MRSA) and 50 methicillin-susceptible (MSSA) S. aureus, as well as 50 vancomycin-resistant enterococci (VRE) and 50 vancomycin-susceptible enterococci (VSE) isolates were used for the study. Optimal test conditions were derived by investigating the effects of inoculum size, medium, incubation temperature and broth filtration. We proposed four different statistical approaches for rapid discrimination between resistant and susceptible bacteria. The statistical approach based on raw measurements of bacterial concentrations delivered sensitivity of 100% and specificity of 94% for discrimination between MRSA and MSSA already after 3 hours of incubation. Categorical agreement of ≥90% was achieved after 140 min with this approach. Differentiation between VRE and VSE was possible with 98% sensitivity and 92% specificity after 3 hours, using a sophisticated statistical approach based on concentration slopes derived from the raw concentration measurements. This approach provided categorical agreement of ≥90% after 165 min. The sensitivity and specificity estimates were confirmed by leave-one-out cross validation. In conclusion, the phenotypic AST methods developed in this study are promising for rapid detection of MRSA and VRE. The development and application of this technology would allow early detection of the resistant pathogens, thus facilitating swift change to the targeted antimicrobial treatment as well as timely initiation of appropriate infection control measures. Further studies are warranted to validate this approach for the detection of other resistance phenotypes, including direct testing from clinical specimens.

Tilted membrane panel: A new module concept to maximize the impact of air bubbles for membrane fouling control in microalgae harvesting

Microalgae harvesting using membrane technology is challenging because of its high fouling propensity. As an established fouling mitigation technique, efficacy of air bubbles can be improved by maximizing the impact of shear-rates in scouring foulant. In this study, it is achieved by tilting the membrane panel. We investigate the effect of tilting angle, switching period as well as aeration rate during microalgal broth filtration. Results show that higher tilting angles (up to 20°) improve permeability of up to 2.7 times of the vertical panel. In addition, operating a one-sided panel is better than a two-sided panel, in which the later involved switching mode. One-sided membrane panel only require a half of area, yet its performance is comparable with of a large-scale module. This tilted panel can lead to significant membrane cost reductions and eventually improves the competitiveness of membrane technology for microalgae harvesting application.

Antibacterial activities of penicillic acid isolated from Aspergillus persii against various plant pathogenic bacteria.

The emergence of pathogenic bacterial strains resistant to agrochemicals and the increasing demand for organic foods have led to the discovery of new antibacterial metabolites that can be used either directly or as a lead molecule for development of synthetic bactericides. During the screening of antibacterial fungal cultures, we found that one fungal strain, Aspergillus persii EML-HPB1-11, showed strong invitro antibacterial activity against Xanthomonas arboricola pv.pruni (Xap) with a minimum inhibitory concentration (MIC) of 10% of fermentation broth filtrate. The active compound was identified as penicillic acid (PA: 3-methoxy-5-methyl-4-oxo-2,5-hexadienoic acid) by mass and NMR spectroscopy. The invitro antibacterial activity of PA was tested against 12 phytopathogenic bacteria. All of the bacterial pathogens tested were highly inhibited by PA with MIC values of 12·3-111·1μgml(-1) . It also effectively suppressed the development of bacterial spot disease in detached peach leaves, showing control values of 82·4 and 94·1% at concentrations of 111·1 and 333·3μgml(-1) respectively. This is the first report on the production of PA by A.persii. This study suggests that PA can be used as a lead molecule for development of synthetic bactericides for control of various plant diseases. Penicillic acid (PA) produced by the seed-borne fungus Aspergillus persii EML-HPB1-11 showed antibacterial activity against various plant pathogenic bacteria. The compound effectively inhibited the growth of 12 plant pathogenic bacteria and successfully controlled bacterial spot disease on peach leaf. These results suggest that PA can be used as a lead molecule for development of synthetic agrochemicals to control plant bacterial diseases.