Types Of Solid Media Research Articles

The Cultural and Morphological Variability of Botrytis sp. isolates Causing Grey Mould of Gladiolus in India

The gladiolus is one of the important cut flower with the utmost commercial value in India. Gladiolus has about 180 species and over 30,000 cultivars, of which over 20 are produced in India for production of flowers commercially. Botrytis grey mould (BGM) caused by the fungus Botrytis cinerea is one of the most destructive disease of the gladiolus. In a present study, a total 35 isolates of Botrytis were obtained from the gladiolus surveyed area. Colony morphological studies (texture, form, color, production and degree of sporulation) has been conducted using three types of solid media i.e. PDA (Potato Dextrose Agar), Czapeck’sDox Agar, Kritzmen and Netzer Agar medium. All B. cinerea strains gave maximum fungal mycelium growth on PDA (90.0 mm to 87.5mm) and CDA than K and N medium. Spores of Botrytis cinerea was also observed under Scanning Electron Microscope (SEM) and Phase Contrast Microscope (PCM) for conidial size and number of conidia. Maximum conidial size was recorded on PDA in comparison to CDA and KN media.

Production of conidia using different culture media modifies the virulence of the entomopathogenic fungus Metarhiziumys against Aedes aegypti larvae.

Entomopathogenic fungi are being investigated for the biological control of a range of mosquitoes. Metarhizium conidiospores (conidia) effectively kill Aedes aegypti larvae and could be deployed as an alternative to chemical insecticides. Conidial yield and virulence of fungi when cultured on three different types of solid media, was investigated. Three culture media were tested: a) Sabouraud dextrose agar (SDA); b) rice flour yeast agar (RYA) and c) rice grains. Conidia produced using these substrates were tested for virulence against Ae. aegypti larvae obtained from field collected eggs. Larvae (2nd - 3rd instar) were exposed to aqueous conidial suspensions and survival monitored over 7 days. Survival analysis was performed using Log-Rank and Kaplan Meier tests, while fungal growth and conidial yields were analyzed using a two-way ANOVA. There were only small differences between growth rates on RYA and SDA; however, ESALQ 818 showed the highest conidial yield on rice. Conidia produced on rice grains were more virulent, rapidly reducing survival rates of mosquito larvae. ESALQ 818 conidia produced on rice grains, RYA and SDA killed 100% of the larvae on the 2nd, 3rd and 4th day of exposure, respectively. IP 46 virulence of was consistently lower than ESALQ 818 for all the media tested. The choice of culture media can influence the virulence of fungal conidia to Ae. aegypti larvae, demonstrating the importance of not only selecting the most virulent isolate but also standardizing growth conditions when screening for virulence.

Bacillus subtilis Biofilm Development - A Computerized Study of Morphology and Kinetics.

Biofilm is commonly defined as accumulation of microbes, embedded in a self-secreted extra-cellular matrix, on solid surfaces or liquid interfaces. In this study, we analyze several aspects of Bacillus subtilis biofilm formation using tools from the field of image processing. Specifically, we characterize the growth kinetics and morphological features of B. subtilis colony type biofilm formation and compare these in colonies grown on two different types of solid media. Additionally, we propose a model for assessing B. subtilis biofilm complexity across different growth conditions. GFP-labeled B. subtilis cells were cultured on agar surfaces over a 4-day period during which microscopic images of developing colonies were taken at equal time intervals. The images were used to perform a computerized analysis of few aspects of biofilm development, based on features that characterize the different phenotypes of B. subtilis colonies. Specifically, the analysis focused on the segmented structure of the colonies, consisting of two different regions of sub-populations that comprise the biofilm – a central “core” region and an “expanding” region surrounding it. Our results demonstrate that complex biofilm of B. subtillis grown on biofilm-promoting medium [standard lysogeny broth (LB) supplemented with manganese and glycerol] is characterized by rapidly developing three-dimensional complex structure observed at its core compared to biofilm grown on standard LB. As the biofilm develops, the core size remains largely unchanged during development and colony expansion is mostly attributed to the expansion in area of outer cell sub-populations. Moreover, when comparing the bacterial growth on biofilm-promoting agar to that of colonies grown on LB, we found a significant decrease in the GFP production of colonies that formed a more complex biofilm. This suggests that complex biofilm formation has a diminishing effect on cell populations at the biofilm core, likely due to a combination of reduced metabolic rate and increased levels of cell death within this region.

Mycotoxin production of Fusarium langsethiae and Fusarium sporotrichioides on cereal-based substrates

The present study investigated and compared the mycotoxin production of two Fusarium species, F. sporotrichioides and F. langsethiae, isolated from grain samples. Fusarium strains were cultivated at 25°C for 7 days on two types of solid media, i.e. rice-flour and cereal-flour agar. Toxins produced were measured after the incubation period with a multi-mycotoxin method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS). Both F. sporotrichioides and F. langsethiae synthesised type-A trichothecenes, i.e. T-2 and HT-2 toxins, diacetoxyscirpenol (DAS) and neosolaniol (NEO). In addition, both species could be verified as beauvericin producers. The toxin production occurred in both cereal-based assays but was more predominant on the carbohydrate-rich rice-flour medium. The two species were potent producers of T-2 toxin, the highest amounts measured being at a level of 20,000μg/kg after 7 days' incubation. Differences between the species were observed regarding the quantitative production of the other trichothecenes: F. sporotrichioides was a more prolific producer of HT-2 toxin and beauvericin, whereas F. langsethiae produced higher amounts of DAS and NEO. On rice-flour assay, the toxin production was monitored during the growth period. The production started rapidly at an early growth phase and several toxins could be detected already after the 1st day of incubation, the highest concentrations being at mg/kg level. The results also indicated that the biosynthesis by F. sporotrichioides and F. langsethiae shifted towards the other type-A trichothecenes at the expense of T-2 toxin at the end of the cultivation.

Evaluation of inoculum performance for enhancing gamma-linolenic acid production from Mucor rouxii

To facilitate a cost-effective preparation of spore inoculum with good capacity for gamma-linolenic acid (GLA) production from Mucor rouxii. Sporangiospore production, mycelial growth ability and fatty acid composition of M. rouxii were determined. Compared with fungal cultivation on solid semi-synthetic media, high spore production was achieved from M. rouxii grown on rice grains, particularly polished rice (30.7 g kg(-1) initial substrate). Variations in the fatty acid profiles were found in the spores grown on different types of solid media, whereas the spores obtained at different ages from cultivated polished rice showed a similar fatty acid profile. Using the inocula from different spore-forming media and culture ages, and low temperature storage, not much change in the vegetative growth of submerged cultures or fatty acid composition of mycelia was observed. The spores generated on polished rice exhibited a high performance for GLA production. Age of spore and timing of spore storage at low temperature did not affect on fatty acid profile of the mycelial cultures. The simple, low cost method of inoculum preparation can be applied for large-scale production of GLA-rich oils, which reduce a time constraint and variation in fatty acid composition.

Study of pyrene biodegradation capacity in two types of solid media

Removal of pyrene, a representative PAH, was studied using laboratory tests in two different types of solid media: an organic matter collected on the surface of a vertical flow constructed wetland (VFCW) and a formulated clay silicate sand (inorganic matter). The aim of this study was to evaluate the capacity of pyrene biodegradation in these media in order to use them for treating run-off water. The sorption process, the kinetics of pyrene biodegradation and the influence of selected bacteria were also investigated. The sorption process was evaluated by adsorption isotherms and desorption kinetics using a batch equilibration method. The adsorption coefficient values of 28.8 and 2.1 for the organic and the inorganic matter respectively, confirmed the relationship of adsorption with organic carbon content. A small proportion of the sorbed pyrene was available for desorption (8% and 15% for the organic and the inorganic matter, respectively), indicating that sorption was partially irreversible, with the presence of hysteresis. For the formulated clay silicate sand inoculated with a specific bacteria (Mycobacterium sp.6PY1), selected for its ability to degrade PAHs, pyrene removal was complete in 32 days. With the organic matter, these values ranged from 40% to 95% for the different experiments, following a lag time of 3 weeks before observation of a significant degradation. Indigenous bacterial species in the organic medium had the metabolic capacity to degrade pyrene, and microbial populations pre-exposed to the PAH degraded pyrene faster than similar unexposed populations. Three metabolites of pyrene degradation by Mycobacterium were found. They accumulated in both organic and inorganic matter, indicating that the enzymes catalyzing them have slow kinetics.

TWO DISTINCT COLONIAL MORPHOTYPES OF AMPHORA COFFEAEFORMIS (BACILLARIOPHYCEAE) CULTURED ON SOLID MEDIA1

ABSTRACTWhen cultured on different types of solid media, the marine‐fouling diatom Amphora coffeaeformis (Ag.) Kütz. consistently formed two distinct colonial morphotypes named tight and fuzzy. Tight colonies were comprised mainly of small, morphologically distorted, nonmotile cells, whereas morphologically normal and highly motile cells formed the fuzzy colonies. Cells from tight colonies were less adherent to glass, grew more slowly in liquid media, and had a slightly decreased viability on plates with copper than cells from fuzzy colonies. Whereas the protein profiles of the two types of cells were nearly identical in polyacrylamide gels stained with Coomassie blue, cells from tight colonies produced a significantly lower amount of a protease‐resistant, low Mr polysaccharide or glycoconjugate as detected in silver‐stained gels. The frequency of appearance of the fuzzy and tight morphotypes was not influenced by the mode of nutrition or the type of substratum to which the algal cells adhered. However, certain formulations of solid medium and the presence of growth‐inhibitory concentrations of copper in agar plates favored the formation of tight colonies. Due to their frequencies and patterns of appearance, it was clear that the two naturally formed morphotypes were not the consequence of spontaneous mutations, genetic rearrangement, or selection of stable natural variants, and we have hypothesized that they were linked to a normal physiological behavior. The tight colonial morphotype was used as a valuable marker to screen for true motility/adhesion mutants within an ultraviolet‐mutagenized population of A. coffeaeformis. Seven mutants were isolated that were non‐motile on agar plates, poorly adherent to glass, and distinguished from naturally formed cells from tight colonies by their inability to form fuzzy colonies upon subculture on solid media.

Selection of representative Alternaria strain groups on the basis of morphology, enzyme profile, and allergen content

In an attempt to identify representative strains, 12 strains of Alternaria alternata were contributed by four different research groups. Each was grown on two types of solid media and characterized with descriptions of pigmentation and morphology. Enzyme profiles were determined on both the cellular antigen and the culture filtrate material with use of a commercial kit. Concentrations of a previously described Alt a I and a 70 kd allergen, GP70, were measured by a two-antibody “sandwich” ELISA. Allergenic proteins were visualized by IgE immunoblots. With use of these criteria, four separate strains were identified that might serve as representative of Alternaria for further research.

Effects of certain variables on the L-colony production in Staphylococcus aureus in the presence of methicillin.

AbstractThe effect of certain variables on L-colony production in Staphylococcus aureus in the presence of methicillin was studied. All the 20 strains studied produced L-colonies. Two types of solid media were compared. A higher frequency of L-colony production as well as better reproducibility was obtained using a serum-free medium. Using 5-hr bacterial cultures as inocula usually resulted in a 10-fold increase in the frequency of L-colony production compared to 24-hr inoculum. 50% CO2 in the incubation atmosphere resulted in a lower L-colony production than 5% CO2. Seven strains producing L-colonies in 5% CO2 failed to do so in 50% CO2 on blood agar medium with 24-hr inoculum. One third of the strains producing L-colonies on serum-free medium in a high frequency were found to have low titres of alpha-hemolysin on the same medium. The possibility is discussed that alpha-hemolysin, or a factor associated with alpha-hemolysin production, is a limiting factor for the L-colony production.

Light regime effect on the growth rate variability ofScenedesmus quadricauda (Turp.) Bréb. Clones originating from cells treated by a mutagen when grown on the surface of a solid medium

The light regime effect on the growth rate variability of clones of one chlorococcal alga strain growing on the surface of a solid medium was studied from the point of view of the clone selections manifesting the desired grade of this complex character. Several combinations of light regimes used for the cultivation of coenobia treated by UV-light and untreated control on two types of solid media proved the significance of manifestation degree changes of this character due to the given light conditions. The sizes of the alga colonies after a certain growth time on the surface of solid medium were evaluated statistically and the values obtained indicated the degree of growth rate manifested by the clones of a given population. The\(\bar x\) and sx values of their growth rate variability were considered as the indicators facilitating the choice of selec-tion type and screening level. This paper is a partial contribution to the solution of the problems concerning the primary selection of alga clones on the surface of solid media.