Showing papers on "Agar plate published in 2018"

Isolation of Previously Uncultured Slow-Growing Bacteria by Using a Simple Modification in the Preparation of Agar Media.

Abstract: Most microorganisms living in the environment have yet to be cultured, owing at least in part to their slow and poor propagation properties and susceptibility to oxidative stress. Our previous studies demonstrated that a simple modification in the preparation of agar media, i.e., autoclaving the phosphate and agar separately (termed “PS” medium), can greatly improve the culturability of microorganisms by mitigating oxidative stress compared with the use of “PT” medium (autoclaving the phosphate and agar together). Here, we attempted to isolate phylogenetically novel bacteria by combining PS medium with prolonged cultivation. After inoculation with forest soil or pond sediment samples, significantly more colonies appeared on PS medium than on PT medium. A total of 98 and 74 colonies that emerged after more than 7 days of cultivation were isolated as slow growers from PS and PT media, respectively. Sequencing analysis of their 16S rRNA genes revealed that the slow growers recovered from PS medium included more phylogenetically novel bacteria than those from PT medium, including a strain that could be classified into a novel order in the class Alphaproteobacteria. Further physiological analysis of representative strains showed that they were actually slow and poor growers and formed small but visible colonies only on PS medium. This study demonstrates that the culturability of previously uncultured bacteria can be improved by using an isolation strategy that combines a simple modification in medium preparation with an extended incubation time. IMPORTANCE Most microbial species inhabiting natural environments have not yet been isolated. One of the serious issues preventing their isolation is intrinsically slow and/or poor growth. Moreover, these slow and/or poor growers are likely to be highly sensitive to environmental stresses, especially oxidative stress. We reported previously that interaction between agar and phosphate during autoclave sterilization generates hydrogen peroxide, which adversely affects the culturability of environmental microorganisms, in particular, slow-growing organisms vulnerable to oxidative stress. In this study, we successfully isolated many slow-growing bacterial strains with phylogenetic novelty by simply modifying their cultivation on agar plates, i.e., autoclaving the phosphate and agar separately. The current limited repertoire of culture techniques still has room for improvement in the isolation of microorganisms previously considered unculturable.

Evaluation of colistin stability in agar and comparison of four methods for MIC testing of colistin

Abstract: Susceptibility testing for colistin remains challenging primarily due to its inherent properties. We evaluated colistin stability in agar and reproducibility of colistin MICs obtained by agar dilution, broth macro- and micro-dilution and MIC gradient strips on 3–7 iterations of each method using clinical Klebsiella pneumoniae (susceptible-CS, and resistant-CR, n = 2 each), mcr-harboring Escherichia coli (n = 2), and reference strains E. coli ATCC25922 and Pseudomonas aeruginosa ATCC27853. MICs for reference strains were not in the given range using Etest and broth microdilution (ATCC25922, 0.125 and 4 μg/ml, respectively). MICs of CR-1 and CR-2, and of the mcr-harboring E. coli showed high concordance between agar and broth dilution varying up to one 2-fold dilution. However, remarkable variations were observed on broth dilution with CS-1 and CS-2 (MIC range 0.25–32 and 0.5–64 μg/ml, respectively); whereas for agar dilution the MIC for both CS strains was 0.5 μg/ml in all the runs. MICs obtained by MIC gradient strips were lower than those obtained by dilution methods (1–2 dilutions for CS and mcr strains, and up to five dilutions for CR strains). To confirm uniform distribution of colistin in agar, a single strain was spotted in five different regions of the same plate. All spots showed concordant growth with maximum one dilution difference. No effect on MIC was found due to storage of colistin-containing agar plates for 7 days at 4 °C. In our hands, agar dilution was superior in terms of reproducibility and robustness, compared to broth dilution methods, for colistin MIC determination.

Biodegradative potential of fungal isolates from sacral ambient: In vitro study as risk assessment implication for the conservation of wall paintings.

Abstract: The principal purpose of the study was to evaluate in vitro the potential ability of fungal isolates obtained from the painted layer of frescoes and surrounding air to induce symptoms of fresco deterioration, associated with their growth and metabolism, so that the risk of such deterioration can be precisely assessed and appropriate conservation treatments formulated. Biodegradative properties of the tested microfungi were qualitatively characterized through the use of a set of special agar plates: CaCO3 glucose agar (calcite dissolution), casein nutrient agar (casein hydrolysis), Czapek-Dox minimal medium (pigment secretion); and Czapek-Dox minimal broth (acid and alkali production). Most of the tested isolates (71.05%) demonstrated at least one of the degradative properties, with Penicillium bilaiae as the most potent, since it tested positive in all four. The remaining isolates (28.95%) showed no deterioration capabilities and were hence considered unlikely to partake in the complex process of fungal deterioration of murals via the tested mechanisms. The obtained results clearly indicate that utilization of fast and simple plate assays can provide insight into the biodegradative potential of deteriogenic fungi and allow for their separation from allochthonous transients, a prerequisite for precise assessment of the amount of risk posed by a thriving mycobiota to mural paintings.

Isolation and characterization of a cold-active, alkaline, detergent stable α-amylase from a novel bacterium Bacillus subtilis N8.

Abstract: A cold-active alkaline amylase producer Bacillus subtilis N8 was isolated from soil samples. Amylase synthesis optimally occurred at 15°C and pH 10.0 on agar plates containing starch. The molecular...

Control of mould growth by Lactobacillus rhamnosus VT1 and Lactobacillus reuteri CCM 3625 on milk agar plates

Abstract: The possibility to control mould growth by Lactobacillus rhamnosus VT1 and Lactobacillus reuteri CCM 3625 in a milk environment was assessed using the milk agar plate method Higher antifungal activity was exhibited by actively growing cells of both lactobacilli strains compared with the MRS broth supernatants of both bacterial strains containing metabolites with antifungal activity The control of mould growth by Lactobacillus reuteri CCM 3625 was proved to be associated with the production of the mixture of lactic (09 % w/w), acetic (02 % w/w), and succinic (02 % w/w) acids The mechanism of mould growth control by Lactobacillus rhamnosus VT1 probably consists in the production of lactic acid (12 % w/w) together with some other metabolite(s) of non-proteinaceous and non-saccharidic nature with antifungal activity

Evaluation of Biofilm Formation and Presence of Ica Genes in Staphylococcus epidermidis Clinical Isolates.

Abstract: Objectives: Biofilm formation is one of the important features of Staphylococcus epidermidis, particularly in nosocomial infections. We aimed to investigate the biofilm production by phenotypic methods and the presence of ica genes in S epidermidis. Methods: A total of 41 S epidermidis isolates were recovered from different clinical specimens. Biofilm formation was evaluated by microtiter plate, tube method and Congo red agar method. The presence of icaA and icaD genes was investigated by PCR. Validity of methods (sensitivity and specificity), and metrics for test performance (positive/negative predictive value, and positive/negative likelihood ratio) were determined. Results: By both microtiter plate and tube method, 53.6 of S epidermidis isolates were able to produce biofilm, whilst only 24.4 of isolates provided a biofilm phenotype on Congo red agar plates. icaA and icaD genes were found in 100 and 95.1 of isolates, respectively. Biofilm phenotypes accounted for 4.8 by microtiter plate assay, despite the absence of the ica gene. Congo red agar and PCR exhibited a lower sensitivity (18 and 45.5, respectively) for identifying the biofilm phenotype in comparison to microtiter plate. Conclusion: The microtiter plate method remains generally a better tool to screen biofilm production in S epidermidis. In addition, the ability of S epidermidis to form biofilm is not always dependent on the presence of ica genes, highlighting the importance of ica-independent mechanisms of biofilm formation. The use of reliable methods to specifically detect biofilms can be helpful to treat the patients affected by such problematic bacteria. © 2018 Korea Centers for Disease Control and Prevention.

Isolation, characterization and purification of xylanase producing bacteria from sea sediment

Abstract: Xylan is the most important natural hemicellulose which has several industrial applications such as food, textile, bleaching of cellulose pulp, seed germination, degumming and agro waste treatment. Micro-organisms play a major role in the production of xylanase enzyme. In the present research, an attempt has been made to produce the xylanase enzyme from bacterial strains. The sea sediment was collected from Kovalam beach, Chennai (Latitude: 8.4004° North, Longitude: 76.9787° East) and serial dilution was done. The serially diluted sample was plated on xylan agar medium. The isolates were characterized and identified based on morphological, biochemical and physiological characters. The zones of hydrolysis for twelve xylan utilizing bacterial isolates were obtained. Of the 12 bacterial isolates, the species obtained from the serial dilution of 10−8 showed higher activity. The single colonies from the xylan agar plate was isolated and grown in nutrient broth supplemented with xylan in shake flask. The culture medium was centrifuged and the supernatant was used as crude enzyme. The enzyme partially purified to homogeneity by a combination of Ammonium-sulphate precipitation and dialyzed using culture supernatant as crude enzyme. The activity of the enzyme xylanase was assayed by DNSA method. The enzyme was optimally active at temperature 55 oC and pH 9.0. The enzyme showed 95%, 90%, and 85% thermal stability at 55 °C, 60 °C and 65 °C. The enzyme was stable over a broad pH range of 8.0–10.0.

Evaluation of an aphid-rearing method using excised leaves and agar medium

Abstract: The present study evaluated the effectiveness of an aphid‐rearing method devised by Milner in 1981 using Acyrthosiphon pisum and its host plant Vicia faba. In the “agar‐leaf method,” excised leaves of V. faba were attached to the surface of 1% agar gel containing nutrient solution, and test aphids were transferred onto the leaves. Excised leaves grew in size and weight on the agar medium. Fecundity, longevity, body size and developmental time to adulthood were compared between aphids reared using the agar‐leaf method vs. those reared on V. faba seedlings under the same conditions. No significant difference was detected between the two treatments for any of the four parameters, suggesting that the aphids grew and reproduced on excised leaves as successfully as on V. faba seedlings. This method was also useful for inducing males and oviparous females at lower temperature and in short days. Therefore, the present study confirms the effectiveness of using excised leaves on agar and suggests that this method could be applied to the rearing of other aphids, phytophagous mites, leaf miners and leaf‐gall formers.

Resistance from agar medium impacts the helical growth of Arabidopsis primary roots.

Abstract: Agar is widely used in studies of root growth since it can be mixed at different concentrations to impact mechanical impedance. At high concentrations (1.2–1.5%), growth of Arabidopsis roots has been found to be wavy, but little research has explored this behavior based on a quantitative understanding of mechanical behavior. To this end, agar media with concentration ranging from 0.5% to 1.2% were prepared to produce gradient resistance during root penetration, and Young's moduli and penetrometer resistance were tested. Arabidopsis roots were then cultivated in these agar media with gradient stiffness. The result showed that Young's modulus increased linearly with the increase of concentration of agar media. For Arabidopsis primary roots, it was preferred to develop a helical pattern in agar media with concentration from 0.5% to 1.0%. As stiffness of agar increased, the percentage of helical roots and helix diameters in each agar medium declined; root lengths and auxin distributions showed variety. We demonstrate that the size of helical deformation decreases with agar stiffness as expected by theoretical analysis based on a combination of growth-induced mechanical buckling. In conclusion, the resistance from agar media impacts the properties of root helix, and helical roots growth is driven by growth force. Growth force and external mechanical forces contribute to root phenotypes in Arabidopsis.

Efficacy of Andrographis paniculata compared to Azadirachta indica, Curcuma longa, and sodium hypochlorite when used as root canal irrigants against Candida albicans and Staphylococcus aureus: An in vitro antimicrobial study.

Abstract: Aim: The aim is to test the antimicrobial activity of Andrographis Paniculata, Azadirachta indica (neem), and Curcuma Longa (curcumin) as a root canal irrigant, against Staphylococcus aureus and Candida albicans using agar diffusion test. Sodium hypochlorite (NaOCl) served as a standard control for comparisons. Materials and Methods: The bacterial strains of C. albicans and S. aureus culture were grown overnight (18–20 h) in the brain heart infusion broth at 37°C and inoculated in Mueller–Hinton agar plates. Antibacterial inhibition was assessed using agar well-diffusion method using the methanolic extracts of the three plants to be tested and NaOCl. Bacterial inhibition zone around each well was recorded. The results were tabulated and analyzed statistically for significance. Results: The novel A. paniculata showed significantly higher zone of inhibition against C. albicans (P 0.05). Conclusion: Zones of inhibition exhibited by novel herbal agent A. paniculata were higher against C. albicans and similar against S. aureus, when compared to NaOCl.

Acanthamoeba S13WT relies on its bacterial endosymbiont to backpack human pathogenic bacteria and resist Legionella infection on solid media.

Abstract: Soil-borne amoeba Acanthamoeba S13WT has an endosymbiotic relationship with an environmental Neochlamydia bacterial strain. However, regardless of extensive experiments in liquid media, the biological advantage of the symbiosis remained elusive. We therefore explored the role of the endosymbiont in predator-prey interactions on solid media. A mixed culture of the symbiotic or aposymbiotic amoebae and GFP-expressing Escherichia coli or Salmonella Enteritidis was spotted onto the centre of a LB or B-CYE agar plate preinoculated with a ring of mCherry-expressing Legionella pneumophila (Legionella 'wall'). The spread of the amoebae on the plate was assessed using a fluorescence imaging system or scanning electron microscopy. As a result, in contrast to the aposymbiotic amoebae, the symbiotic amoebae backpacked these GFP-expressing bacteria and formed flower-like fluorescence patterns in an anticlockwise direction. Other bacteria (Pseudomonas aeruginosa and Stenotrophomonas maltophilia), but not Staphylococcus aureus, were also backpacked by the symbiotic amoebae on LB agar, although lacked the movement to anticlockwise direction. Furthermore, in contrast to the aposymbiotic amoebae, the symbiotic amoebae backpacking the E. coli broke through the Legionella 'wall' on B-CYE agar plates. Thus, we concluded that Acanthamoeba S13WT required the Neochlamydia endosymbiont to backpack human pathogenic bacteria and resist Legionella infection on solid agar.

Isolation, screening and determination of α-amylase activity from marine streptomyces species

Abstract: Objective: This study was aimed to isolate potent amylase producing Streptomyces from the marine source. Methods: Soil samples were collected from less explored mangrove regions of Muthupet, Tamilnadu. Isolation of Streptomyces was performed by serial dilution plate technique using starch casein agar (SCA) (pH 7.2 and temp 28 °C). Morphological and biochemical characteristics were studied using Bergey’s manual of systematic bacteriology. Preliminary screening and quantification of amylase activities were analysed in selected Streptomyces isolates by starch agar plate and dinitrosalicylic acid (DNS) method respectively. Results: Totally 65 isolates were separated from the marine soil. Among them, 23 strains showed different morphological features. These strains were subjected to amylase activity. Eight Streptomyces isolates (S1-S8) exhibited positive for amylase activity. The zone of clearance was exhibited in the range of diameters between 4-20 mm. Fermentation was prompted with inorganic salt starch agar, international Streptomyces project (ISP-4) media at 28 °C and incubated in an orbital shaker at 250 rpm for 96 h (pH 7.5). The quantitative estimation of amylase activity was exhibited selected eight isolates in the range between 2.4±0.002-5.9±0.005 (U/ml). The Streptomyces species S4, S5 and S6 exhibited strong amylase activity in both qualitative and quantitative level. Conclusion: This work motivating the amylase producing Streptomyces are originated in mangroves and it proved Streptomyces sp. S6 has a more efficient source of amylase production.

Rapid detection and differentiation of Staphylococcus colonies using an optical scattering technology.

Abstract: Staphylococcus species are a major pathogen responsible for nosocomial infections and foodborne illnesses. We applied a laser-based BARDOT (bacterial rapid detection using optical scattering technology) for rapid colony screening and detection of Staphylococcus on an agar plate and differentiate these from non-Staphylococcus spp. Among the six growth media tested, phenol red mannitol agar (PRMA) was found most suitable for building the Staphylococcus species scatter image libraries. Scatter image library for Staphylococcus species gave a high positive predictive value (PPV 87.5-100%) when tested against known laboratory strains of Staphylococcus spp., while the PPV against non-Staphylococcus spp. was 0-38%. A total of nine naturally contaminated bovine raw milk and ready-to-eat chicken salad samples were tested, and BARDOT detected Staphylococcus including Staphylococcus aureus with 80-100% PPV. Forty-five BARDOT-identified bacterial isolates from naturally contaminated foods were further confirmed by tuf and nuc gene-specific PCR and 16S rRNA gene sequence. This label-free, non-invasive on-plate colony screening technology can be adopted by the food industries, biotechnology companies, and public health laboratories for Staphylococcus species detection including S. aureus from various samples for food safety and public health management. Graphical abstract.

A novel design to screen chlorogenic acid-producing microbial strains from the environment.

Abstract: The present study aimed to develop a plate-screening method, based on the specific color development of complexes formed between chlorogenic acid, a valuable plant-derived compound, and aluminum (III), to detect chlorogenic acid-producing microbial strains. Modified media with 0.75 mM aluminum chloride were developed to identify CGA-producing bacteria (based on beef extract agar medium) or fungi (based on the potato dextrose agar medium). Compared with conventional screening, the modified media let to 3.3 times more CGA producers from plants, at 90.9% selective accuracy. Novel chlorogenic acid-biosynthesizing strains included Brevibacillus borstelensis B14, Bacillus amyloliquefaciens B17, Bacillus badius B19, Sphingomonas yabuuchiae N21, Enterobacter tabaci N22, and Lodderomyces elongisporus S216 and P212. Strain S216 produced the highest chlorogenic acid yield (23.39 mg L−1). This study provides a highly efficient and low-cost tool for quick detection and subsequent identification of several newly isolated strains with chlorogenic acid-producing potential.

A combination of rapid and easy assays of biosurfactant producing bacterial strain isolated from automobiles repairing workshop in Aligarh

Abstract: Routine washing, cleaning, repairing, maintenance of cars, bikes, scooters and disposal of waste of all kinds are carried out in automobile workshops are common observations in Aligarh. Considering the likelihood of existence of biosurfactant producing organisms at hydrocarbon contaminated site, a large number of soil samples were collected and isolation was carried out. A total of ten bacterial strains ALIG (01–10) were isolated out of which only isolate АLIG01 grown on GSP agar, Maconkey agar as well as on Pseudomonas agar plates which indicated suspected Pseudomonas spp . and exhibits positive biosurfactant activity through penetration assay, oil spreading technique, beta hemolytic activity and ЕI24 (96%), positive blue plate agar plate (> 2сm), qualatitative analysis, tolerance against hydrocarbon m -xylene, and microplate assay. This isolate АLIG01 is a valuable source to investigate further for future agriculture plant pathology and industrial applications.

Isolation and identification of bacteria from fresh guava (Psidium guajava) sold at local markets in Mymensingh and their antibiogram profile.

Abstract: Aim The study was conducted for the isolation, identification, and antibiogram of bacteria obtained from fresh guava (Psidium guajava). Materials and methods A total of 25 fresh guavas were collected from five markets located in Mymensingh city. Guava samples were cultured onto various selective media such as eosin methylene blue, xylose lysine deoxycholate, thiosulfate-citrate-bile salts-sucrose, blood agar, and mannitol salt agar for the isolation of bacteria. Biochemical tests (dextrose, maltose, lactose, sucrose, mannitol, methyl red, Voges-Proskauer, and indole) were performed to identify the bacteria. Results Total viable counts of guava were ranged between log 6.56 colony-forming unit (cfu)/ml and 6.62 cfu/ml. A total of 106 bacterial isolates belonged to five genera (Escherichia coli, Salmonella spp., Vibrio spp., Bacillus spp., and Staphylococcus spp.) were identified. Salmonella spp. (23.6%) was the most prevalent, followed by E. coli (22.64%), Bacillus spp. (19.81%), Staphylococcus spp. (17.92%), and Vibrio spp. (16.03%). The results of antibiotic sensitivity test showed that Salmonella spp., Bacillus spp., and E. coli were sensitive to chloramphenicol, ciprofloxacin, and gentamicin and resistant to ampicillin and cephalexin. Vibrio spp. was sensitive to chloramphenicol and gentamicin, intermediately sensitive to ciprofloxacin and ampicillin and resistant to cephalexin. Conclusion The results of this study indicate that fresh guava contains multidrug-resistant bacteria which might pose a public health risk.

Evaluation of efficacy of repeated decontamination and sterilization of single‐incision laparoscopic surgery ports intended for 1‐time use

Abstract: Objective To determine the efficacy of repeated decontamination and sterilization of a disposable port intended for 1-time use during single-incision laparoscopy. Study design Experimental; prospective, controlled design. Methods Six single-access ports used 4 times and 6 single-access ports used 8 times to perform various clean, minimally invasive surgeries were evaluated. Ports were decontaminated in an enzymatic cleaner (dilution, 3:100) and cleaned with a scrub brush for 5 minutes. The ports were then sterilized with hydrogen peroxide vapor for 50 minutes using a standard protocol at a concentration of 6 mg/L, followed by a vapor diffusion phase. Samples taken from the foam, insufflating tubing, and rigid cannula portion of each port were collected with aseptic technique for aerobic-anaerobic cultures. Port material samples were set up on a tryptic soy agar plate with 5% sheep blood, a MacConkey agar plate, and a Columbia agar plate with 5% sheep blood (CAP). Anaerobic isolate cultures were set up on Centers for Disease Control and Prevention (CDC) blood agar and CAP. Results None of the ports used 4 times had positive bacteriologic culture. Two of the ports used 8 times had a light growth of bacteria. The first positive sample cultured Staphylococcus spp. and Micrococcus spp. The second positive sample cultured Staphylococcus epidermidis. The positive cultures were obtained from the foam component in an enriched broth. Conclusion Single-incision ports could be used safely 4 times and pose a low risk of infection to the patient under conditions of this study.

Antibiotic Resistance Pattern of Bacteria Isolated from patients with upper respiratory tract infections; a four year study in Tripoli city

Abstract: Introduction: Respiratory tract infections have been known to be a significant health concern for mortality and morbidity since many years. This study was aimed at determining the prevalence of bacterial pathogen causing upper respiratory tract (URTIs) and the susceptibility patterns to frequently used antibiotics among patients attending Abusetta hospital in Tripoli district. Methods: A total of 1,110 throat swabs were collected between Jan, 2011 to December, 2014 and inoculated onto Blood agar, MacCkonkey agar and Chocolate agar then incubated at 37 oC for 24 hours. Bacterial pathogens were determined by bacteriological culture methods and antibiotic susceptibility of the isolates was identified following Clinical Laboratory Standard Institute guidelines (CLSI). Results: Of the 1,110 respiratory samples tested, 71.1% (n = 789) of specimens were positive cultures with the dominant bacterial pathogens being Streptococcus pneumoniae 43.3% (n = 342), followed by Pseudomona aeruginosa 22.8% (n = 180), Staphylococcus aureus 13.8% (n = 109), Escherichia coli 6.9% (n = 55), Enterobacter spp 6.2% (n = 49), Citrobacter 4.5% (n = 36), and Klebsiella 2.2% (n = 18). Most isolates exhibited resistance against the commonly used antibiotics and to at least one antibiotic. Conclusion: The level of antibiotic resistance in this study is alarming and brings to light the timely and suitable diagnosis of the common bacteria causes of URTIs and proper antibiotic administration based on susceptibility test.

Isolation and characterization of starch degrading rhizobacteria from soil of Jimma University Main Campus, Ethiopia

Abstract: Starch degrading bacteria are important for different industries such as food, fermentation, textile, and paper. The aim of this study is to isolate and characterize bacteria able to degrade starch from the rhizospheres of various plants at four sites located in Jimma University main campus. Collected soil samples were labeled as kobo (AJUMC), Avocado (BJUMC), Banana (CJUMC), and Cana indica (DJUMC) respectively. Soil samples were serially diluted in sterilized peptone water, poured on sterilized starch agar plates, and incubated at 32oC for 48 h. The representative colonies showing different morphology was randomly picked up using the streaking method on nutrient agar. A total of 53 bacterial isolates were obtained from the soils rhizospheres. Microscopic characteristics showed that among the 53 isolates, 38 (72%) were Gram-positive rod shaped bacteria, while 15 (28%) were Gram-negative rod shaped bacteria. Based on the biochemical tests, the results revealed that the 38 isolates belonged to the genera Bacillus while the remaining isolates belonged to the genera Pseudomonas. All isolates were catalase positive and only 15 isolates (Pseudomonas) were KOH positive with negative growth at 80°C, while the 38 (Bacillus) isolates have positive growth at 80oC. The highest values of starch degrading index were the Gram positive bacteria isolates. The amylase activity was also carried out with respect to time, temperature and pH of the media. The maximum activity of amylase at different temperatures from 35 to 45°C was recorded at 35°C (0.94 U/ml) within 24 h, while maximum activity at different pH from 5 to 9 was recorded at pH 7 (1 U/ml). Key words: Rhizobacteria, starch degrading, amylase enzyme, Bacillus, Pseudomonas.

Growth of a common planktonic diatom quantified using solid medium culturing.

Abstract: The ability to grow on solid culture medium is a pre-requisite for a successful microbial genetic model organism. Skeletonema marinoi, a bloom-forming, planktonic marine microalga, is widely used in ecological, evolutionary and population genetics studies. We have tested and confirmed the ability of this common organism to grow on solid culture medium (agar) under experimentally manipulated conditions. We established a protocol for quantifying growth characteristics - length of lag phase, growth rate, maximum biomass yield - on agar medium. The procedure was tested under experimental treatments and the resulting growth changes correlated with those observed in standard liquid culture. The ability to grow on solid medium broadens the use of S. marinoi as a molecular model, where agar is routinely used for various purposes (growth, selection, storage); and the possibility to quantify colony growth opens the way for high throughput, automated, or semi-automated phenotyping solutions.

Physiological and Molecular Characterization of Cephaleuros virescens Occurring in Mango Trees.

Abstract: The objective of this work was to accomplish the isolation, molecular identification and characterizing the physiology of the causal agent of the algal spot in mango trees. For this purpose, the pathogen growth was assessed in different culture media, with subsequent observation and measurements of the filamentous cells. The molecular identification was made using mycelium obtained from leaf lesions and pure algae colonies grown in culture medium. Descriptions based on DNA sequencing indicated that the algae is Cephaleuros virescens. The algae must be isolated primarily in liquid medium for further pricking into agar medium. The highest mycelial growth average in Petri dishes occurred when the algae were grown in Trebouxia and BBM. Trebouxia enabled larger cells in the filamentous cells when compared to other culture media.