Influence Of Inoculum Concentration Research Articles

Modifications of antifungal sensibility testing as suggested by CLSI document M27-A4: proposal for using different culture medium and buffer

A common strategy in antifungal susceptibility testing is the utilization of the standardized protocol based on the microbroth dilution assay approach as described by the Clinical Laboratory Standards Institute (CLSI) (M27-A4). One major problem for laboratories in resource-limited countries with this protocol arises from the use of expensive culture media like RPMI-1640 and 3-N-morpholinopropanesulfonic acid (MOPS) buffer. One approach of circumventing this problem in cases of economic need is the evaluation of alternative culture media and buffers. The overall goal of this work was to investigate the influence of modifications in the protocol M27-A4 on diagnostic reliability. We performed univariate analyses evaluating (1) 2 different culture media (YNB and modified SAB); (2) three different buffers (sodium bicarbonate, Tris-HCL, and phosphate), as well as the influence of inoculum concentration (102, 103, 104, 105 cells/mL), the influence of incubation time, and the influence of the assessment mode (visual, biological dye, and spectrophotometer). Our results suggested that (1) RPMI-1640 may be substituted by modified SAB and (2) MOPS buffer may be substituted by Tris-HCl buffer for defined analyses. By comparing the CLSI protocol and the alternative protocol proposed in the present study (modified SAB and Tris-HCl buffer) for the assessment of fluconazole susceptibility of eighteen yeasts (clinical isolates), similar results with both methodologies were recorded. We feel that this study should stimulate a discussion on the feasibility and evolution of the M27-A4 protocol in order to include pragmatic alternatives for resource-limited settings.

A New Identification Method Reveals the Resistance of an Extensive-Source Radish Collection to Plasmodiophora brassicae Race 4

Raphanus sativus, an important cruciferous vegetable, has been increasingly affected by clubroot disease. Establishing a stable and accurate resistance identification method for screening resistant germplasms is urgently needed in radish. In this study, the influence of inoculum concentration, inoculation methods, and pH of the substrate on disease occurrence was studied. The result showed that the disease index (DI) was highest at 2 × 108 spores/mL, the efficiency of two-stage combined inoculation methods was higher than others, and pH 6.5 was favorable for the infection of P. brassicae. By using this new method, DIs of 349 radish germplasms varying from 0.00 to 97.04, presented significantly different levels of resistance. Analysis showed that 85.06% germplasms from China were susceptible to P. brassicae, whilst 28 accessions were resistant and mainly distributed in east, southwest, northwest, and south-central China. Most of the exotic germplasms were resistant. Repeated experiments verified the stability and reliability of the method and the identity of germplasm resistance. In total, 13 immune, 5 highly resistant and 21 resistant radish accessions were identified. This study provides an original clubroot-tolerance evaluation technology and valuable materials for the development of broad-spectrum resistant varieties for sustainable clubroot management in radish and other cruciferous crops.

<b>Inoculum concentration and inoculation time for propionic acid production from whey using mixed culture of <i>Lactobacillus helveticus</i> and <i>Propionibacterium freudenreichii</i> PS-1

The production of propionic acid using skim serum by-products of the dairy industry was investigated, and the influence of inoculum concentration of Propionibacterium freudenreichii PS-1 and its time of inoculation for the production of propionic acid was evaluated using mixed culture of Lactobacillus helveticus and Propionibacterium freudenreichii . Initially, the adjustment of propionic bacteria to higher concentrations of propionic acid was tested and kinetic parameters were determined for growth. A central composite rotational design (CCRD) with 11 experiments was carried out, using different inoculum concentrations of P. freudenreichii , which were added to the cultures of lactic bacteria at different times. The maximum specific growth rate for P. freudenreichii decreased from 0.11 to 0.03 hour -1 and the growth time increased from 32h to 100h when concentration of propionic acid in lactate broth increased to 0.25%. The best result for propionic acid production was 3.78 g L -1 , inoculating 5.10 8 CFU mL -1 of propionic bacteria after 6 h. For lactose consumption, the best conditions were inoculum concentration above 5.10 8 CFU mL -1 and inoculation time of P. freudenreichii after 6 hours. Therefore, it was demonstrated that skimmed whey can be used as a renewable, low-cost raw material for propionic acid production by mixed culture.

Septorioza pomidora. I. Rozwój choroby w warunkach szklarniowych i polowych [Septoria leaf spot of tomato. I. Development of septoria leaf spot on tomato plants under greenhouse and field conditions

The number of <i>Septoria lycopersici</i> pycnospores necessary for inducing tomato infection was reported. In addition to this, the influence of inoculum concentration and site of tomato infection as well as the influence of air humidity and temperature on diseasee expression have been researched. Studies upon the character of <i>S. lycopersici</i> penetration and host-plant parasite interaction were made with the susceptible Bounty tomato under greenhouse conditions. The results of observations concerning the appearance and development of septoria leaf spot in the fields of central Poland were also described.

Influence of Inoculum Concentration in the Ethanol Production by Klebsiella pneumoniae

Influence of Inoculum Concentration in the Ethanol Production by Klebsiella pneumoniae

Effects of inoculum concentration, temperature, and carbon sources on tannase production during solid state fermentation of cashew apple bagasse

In this study, the optimization of tannase production by solid state fermentation was investigated using cashew apple bagasse (CAB), an inexpensive residue produced by the cashew apple agroindustry, as a substrate. To accomplish this, CAB was enriched with 2.5% (w/w) tannic acid and 2.5% (w/w) ammonium sulphate and then moistened with water (60 mL/100 g of dry CAB). The influence of inoculum concentration (104 to 107 spores/g), temperature (20, 25, 30, and 35°C) and several additional carbon sources (glucose, starch, sucrose, maltose, analytical grade glycerol, and glycerol produced during biodiesel production) on enzyme production by Aspergillus oryzae was then evaluated. Supplementation with maltose and glycerol inhibited tannase synthesis, which resulted in lower enzyme activity. Starch and sucrose supplementation increased enzyme production, but decreased the enzyme productivity. The maximum tannase activity (4.63 units/g of dry substrate) was obtained at 30°C, using 107 spores/g and 1.0% (w/v) sucrose as an additional carbon source.

Milk-based beverages obtained by Kombucha application

This paper investigates the manufacture of milk-based beverages by application of several Kombucha starters. Local Kombucha culture was grown up on three substrates: sweetened black and green tea, and topinambur. Their concentrates were obtained by vacuum-evaporation and amounts of 10% and 15% (v/v) were applied to milk (2.2% fat). The traditional yoghurt starter (B3) was applied for producing control samples. All fermentations were stopped when the pH reached 4.4. Fermentation curves were registered, linear for yoghurt and sigmoidal for Kombucha. Two times faster process was achieved with yoghurt starter. Influence of inoculum concentration on the rate of fermentation was insignificant. Viscosities were higher for Kombucha beverages at lower speeds of spindle, but lower at higher speeds of spindle. Very high sensory scores were achieved for all beverages, after production and after 5-days’ storage.

Influence of inoculum concentration, leaf age, temperature, and duration of leaf wetness on Septoria blight of parsley

The effect of inoculum concentration, leaf age, temperature, leaf wetness duration on Septoria petroselini infection and the development of Septoria blight of parsley were studied in controlled environment conditions. The mean number of lesions cm −2 of brush-inoculated leaf surface increased 72.4% with increasing inoculum concentration from 10 4 to 2×10 6 conidia ml −1. As leaves of parsley plants matured, they became more susceptible to S. petroselini infection. A nonlinear relationship was found between inoculum concentration and lesion area for young and older leaves. An inoculum concentration of 10 4 conidia ml −1 of S. petroselini seems to be required for disease development. Parsley plants were sprayed, inoculated with conidial suspensions of S. petroselini, exposed to leaf wetness durations of 0, 12, 24, 48, 60, and 72 h, then blight was allowed to develop for 3 weeks at 15, 17, 20, 23, 27, and 32 °C. Septoria blight developed at all temperatures tested. The mean lesion number increased in parsley plants as wetness duration increased at 20 and 23 °C, whereas disease development decreased in parsley leaves as wetness duration increased at temperatures of 15, 17, 27, and 32 °C. The optimum temperatures for lesion development were 20 and 23 °C. At those temperatures, the optimum leaf wetness duration was 72 h. Leaf wetness duration did not contribute to an increase in disease severity at 15, 17, 27, and 32 °C. Leaf area covered by pycnidia apparently increased in treatments at temperatures between 17 and 23 °C during the wetness period of 48 h. Low levels of Septoria blight on parsley develop across a wide temperature range. Leaf wetness duration significantly increases disease severity, but only at optimal temperatures.

Influence of Inoculum Concentration on Development of Verticillium Wilt in Chrysanthemum

Influence of Inoculum Concentration on Development of Verticillium Wilt in Chrysanthemum

The influence of inoculum concentration, relative humidity, and temperature on infection of greenhouse tomatoes by Botrytis cinerea

Botrytis cinerea causes serious crop losses in greenhouse tomato crops through infection of flowers and stem wounds. Experiments were carried out to determine the effects of inoculum concentration, relative humidity (RH), and temperature at these two infection sites. Infection of permanent flower parts increased as a function of inoculum concentration and both length of exposure to high RH (approximately 100% for 0–36 h) and specified continuous RH (56–100%). A low level of infection was still evident under continuous 56% RH. Interruption of periods of high RH with breaks of low RH did not reduce infection. Infection of stem wounds was less dependent on inoculum concentration or RH. Factorial combinations of inoculum concentration, RH, and temperature produced significant interactions. Higher temperature increased infection of flowers but reduced infection of stem wounds. The main implications for control in commercial crops are as follows. Lowering the aerial spore concentration by maintaining the disease at a low level will reduce flower infection. Lowering RH will reduce but not eliminate flower infection but will have only a small effect on stem infection. Raising the temperature (from 15 to 25°C) will reduce stem infection, and whilst flower infection increases, this is counteracted by increased flower production and a decrease in the proportion of infections reaching the peduncle and stem.

Influence of Inoculum Concentration, Temperature and Humidity on the Disease of Annual Bluegrass Caused by Xanthomonas campestris pv. poae JT-P482.

Influence of Inoculum Concentration, Temperature and Humidity on the Disease of Annual Bluegrass Caused by Xanthomonas campestris pv. poae JT-P482.

Influence of Inoculum Concentration on Zone Size in Disk Diffusion Testing

Three different inoculum concentrations of common bacterial isolates were tested against currently used antimicrobial agents to determine the effect on zone sizes in the disk agar diffusion test. When zone sizes from inocula with 107 and 109 colony-forming units/mL were compared with zone sizes from inocula with 108 colony-forming units mL, 38.5% of the former displayed changes in diameter of at least 3 mm. Specific instances of the influence of the inoculum concentration on zone sizes for antimicrobial agents and organisms and the importance of these findings are discussed.

REACTION OF CULTIVATED CEREALS TO CLAVICEPS PURPUREA

The influence of inoculum concentration on the reaction induced in species and cultivars of commercial cereals by two isolates of ergot (Claviceps purpurea (Fr.) Tul.) was investigated. Differences were observed among and within species with respect to each of the three components of the disease reaction, i.e., frequency of sclerotia, size of sclerotia, and amount of honeydew produced. Spring wheat (Triticum aestivum L.) was less susceptible than the other cereal species. Significantly fewer sclerotia were produced on spring wheat except at high and low inoculum concentrations and the sclerotia were smaller and the honeydew less abundant. Inoculation of selected cultivars within each of the cereal species showed that only cultivars of spring wheat and durum wheat (T. durum Desf.) differed in the expression of the disease reaction. The spring wheat cultivar Kenya Farmer, and durum wheat cultivar Carleton were less susceptible than the commercial cultivars. Inoculum concentration affected sclerotial frequency in the species and cultivars tested but did not affect sclerotial size and honeydew development. The two isolates used in this study differed in their ability to induce sclerotia and also affected sclerotia size and honeydew production.