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PubMed2006

Growth of Listeria monocytogenes in fresh-cut coconut as affected by storage conditions and inoculum size.

In this study, the effects of packaging atmosphere (air and modified atmosphere, 65% N2, 30% CO2, and 5% O2), temperature (2, 4, 8, and 12 degrees C) and inoculum size (low inoculum, 102 CFU/g; high inoculum, 5 x 10(5) CFU/g) on the growth of Listeria monocytogenes in minimally processed coconut were investigated. Growth data were fitted to the Gompertz equation, and the sanitary risk time (the time, in days, necessary to observe an increase of 2 log CFU/g in the level of the pathogen) was also calculated. At a higher inoculum level, the health risk was more marked; moreover, as shown by parameter A of the Gompertz equation (maximum increase of cell load data), the sanitary risk time seemed not to be influenced by temperature or by atmosphere type. At a low inoculum level in the air-stored product, the sanitary risk time was strongly influenced by temperature, and a modified atmosphere caused a significant increase in the maximum cell load reached in the stationary phase. The results show that L. monocytogenes not only survives but is able to proliferate on fresh-cut coconut stored in air as well as in a modified atmosphere, even at a very low temperature (2 degrees C); moreover, the presence of a high cell load can lead to a health risk because this pathogen can grow to risk level during the shelf life of the product.

Cocos↗

PubMed2004

Effects of inoculum density and substrate type on saprophytic survival of Phytophthora drechsleri, the causal agent of gummosis (crown and root rot) on pistachio in Rafsanjan, Iran.

In this study, sampling was carrid out on soils around pistachio trees in various regions of Rafsanjan, Iran. Following isolation and identification of Phytophthora isolates, the predominant species was found to be P. drechsleri and used for further investigation. For studying saprophytic survival of the fungus, soils collected from different areas were combined and autoclaved. Sterile soil was divided into 10 parts and mixed with fungal inoculum at various concentrations of 0-9% (w/w) separately. Each soil part (100g) was placed in 15cm diameter plastic pot. Some soils in pots were supplemented with sterile wheat straw whereas others were mixed with pistachio leaves surface sterilized with 5% (v/v) sodium hypochlorite. After 3, 6 and 9 weeks of incubation, five leaves or straws samples were taken from each replicate and cultured on CMA-PARPH medium and the fungal colony formation was monitored. The experiment was performed using completely randomized design with factorial experiments including three factors (substrate type, inoculum density and time), 10 treatments (0-9 g inoculum levels) and nine replicates. The results showed that the type of substrate (wheat straw and pistachio leaf) was very important for the fungal saprophytic survival in that this was significantly greater for the pistachio leaves. Time was also considered another critical factor for the fungal survival. With passing incubation time, saprophytic survival of the fungus declined. Further, it was demonstrated that increasing inoculum density would result in longer survivability of P. drechsleri and maximum fungal survival on substrate was obtained when inoculum density was at 9% (w/w).

Cell Survival↗

PubMed1977

[Relationship between the quality of the inoculum material and carminomycin biosynthesis by a culture of Actinomadura carminata].

The effect of the inoculum mycelium quality on carminomycin biosynthesis by Actinomadura carminata was studied. The time of the organism growth on the culture medium containing cornsteep liquor continued for 6 hours without losing by the inoculum of its seeding qualities during that period. The mycelium growth in the inoculum was more intensive under conditions of moderate aeration, i.e. 0.98-2.64 mg O2H1-min. Anincrease in the aeration rate up to 18.56 mg O2/1-min resulted in the growth suppression up to 40 per cent. No correlation between the aeration rate during the inoculum growth and the culture capacity for carminomycin biosynthesis and of the content of the complex in active components the fermentation medium were observed, when a 5-10 per cent of inoculum was used.

Actinomycetales↗

PubMed1988

Effects of tumor cell viability and inoculum density on growth parameters in the human tumor, soft-agar clonogenic assay.

Four hundred and forty-seven human tumor specimens were accessioned and processed for clonogenic assay, yielding 374 specimens, representing 23 different histiotypes, adequate for culture. Different levels of viable cell inoculum density produced contrasting effects between 255 solid tumors as compared to 72 malignant effusions and 47 bladder washings. All parameters for solid tumor growth were similar except plating efficiency; as inoculum density increased, plating efficiency decreased. For malignant effusions, no significant differences were noted for colony numbers or plating efficiency, but numbers of evaluable cultures increased significantly with increasing inoculum density. Bladder barbotage specimens followed a pattern similar to that of malignant effusions, but the only parameter significantly affected by increasing cell inoculum was colony number which increased proportionally to an increase in number of cells plated. The storage of 109 solid tumors at 4 degrees C, for culture at a later date, resulted in an overall decrease in cell viability (mean, 23.9%) as compared to 161 tumors processed on receipt (mean, 31.1%). This decrease in viability did not adversely affect growth parameters or culture evaluability rates. Based on a lower viable cell inoculum, the percentage of plating efficiencies of stored tumors was significantly higher (geometric mean, 0.127 compared to 0.079 for direct culture), colony numbers were similar for both groups, and culture evaluability rates did not differ greatly (80 and 76%).

Agar↗

PubMed1977

Effect of the inoculum size of cells on the maintenance of diploidy in cultured liver cells of the rat.

In culture, a cloned rat liver cell line, J-5-2, exhibited a high diploidy for 200 days after the last cloning (diploid line) but, thereafter, pseudodiploid cells gradually increased in number (pseudodiploid line). These diploid and pseudodiploid lines were inoculated at various sizes, and chromosome analysis was performed for 75 days of serial passages. Diploid line showed an increase of pseudodiploid cells at a large inoculum size. On the other hand, more than 80% of the cells examined maintained the diploid karyotype at a small inoculum size. Pseudodiploid line showed an increase of pseudodiploid cells at a large inoculum size and of diploid cells at a small inoculum size. These pseudodiploid cells contained three types of marker chromosomes, in which number 1 chromosome was found to be involved by the G-banding methods. The saturation density of the pseudodiploid line was much higher than that of the diploid line, and plating efficiency of the diploid line was also significantly higher than that of the pseudodiploid line, although the populating doubling time of these two lines was almost the same. Possible mechanisms for the effect of different inoculum sizes on the incidence of diploid cells and pseudodiploid cells are discussed.

Animals↗

PubMed2002

Influence of inoculum type, inorganic salt and nitrogen to carbon ratio on sclerotium formation and carotenoid production in surface culture of Penicillium sp. PT95.

This study examined the respective effect of inoculum type, inorganic salt and nitrogen to carbon ratio on sclerotium formation and carotenoid production in surface culture of Penicillium sp. PT95. Neither the spore inoculum nor the mycelial pellet inoculum could result in the formation of sclerotium on a modified Czapek agar medium after incubation of 28 days, whereas the inoculum in the form of sclerotium caused the formation of numerous orange, sand-shaped sclerotia after incubation of 14 days. Among four inorganic salts tested, K(2)HPO(4) was more essential to the sclerotium formation and carotenoid production of strain PT95 as compared to KCl, MgSO(4) or FeSO(4). It was also shown that the combination of K(2)HPO(4), KCl and MgSO(4) could produce the best positive cooperation and give the highest sclerotia biomass (782 mg/plate) and carotenoid content in sclerotium (420 microg/g of dry sclerotia) as well as pigment yield (328 microg/plate). The medium containing 0.24 approximately 0.48 g/l sodium nitrate-nitrogen was effective to both the sclerotium formation and carotenoid production of strain PT95 when available maltose-carbon concentrations were at 5.26 approximately 21.05 g/l. The optimal N:C ratio was found to be 1:25.

Biomass↗

PubMed1998

Heterologous protection of mice from a lethal human H1N1 influenza A virus infection by H3N8 equine defective interfering virus: comparison of defective RNA sequences isolated from the DI inoculum and mouse lung.

We have examined the RNAs involved in the heterologous protection of adult mice from otherwise lethal intranasal infection with mouse-adapted human A/WSN (H1N1) by defective interfering (DI) equine A/equine/Newmarket/7339/79 (H3N8: EQV) influenza virus, as well as the RNAs involved in the protection of WSN- or EQV-infected mice by their homologous DI viruses. The aim of this study was to describe the types of defective RNAs present in protected mice in order to guide the design of potentially protective DI RNAs. The interfering and mouse-protecting activity of DI virus was destroyed by prolonged UV irradiation (iDI virus) demonstrating that protection correlated with an active DI genome, and not viral antigen. Protected mice were all infected but suffered a lower degree of morbidity than those given iDI virus. The DI EQV inoculum contained defective segment 1-8 RNAs while DI WSN inoculum contained only defective segment 1-6 RNAs. However lungs of mice given EQV + DI EQV contained only defective segments 1-4 or 1-6 RNAs (mouse-to-mouse variation), while control mice given EQV or EQV + iDI EQV contained few very defective RNAs. Thus prevention of death was the result of quantitative and/or qualitative differences in defective RNAs administered to the mice. Only defective segments 1-3 RNAs were isolated from the lungs of mice given WSN + DI WSN, confirming the earlier report of Noble and Dimmock (1995). A detailed analysis showed that most defective RNAs isolated from the lungs of mice protected from a lethal WSN infection by DI EQV were EQV in origin. Thus, as no infectious EQV was present, these defective RNAs from the DI EQV inoculum must have been heterologously replicated in mouse lung by WSN. All defective segment 3-6 RNAs isolated were of EQV origin, indicating that they were replicated by WSN in preference to its own. Defective segments 1 and 2 were a mixture of EQV and WSN RNAs. Of 17 defective EQV segment 1-3 sequences from mouse lung, all but three differed in their primary central deletion from 20 defective RNAs isolated from the inoculum. No bias in the break points was evident. A number of minor deletions of 2 or more nts were also present in defective EQV and WSN RNAs in segments 1 and 2, but none in segment 3. Their 5', but not 3', breakpoints were heterogeneous, suggesting that defective RNAs were generated during positive strand synthesis. Two cloned EQV-defective segment 3 RNAs were chimeras containing a 30 nt insert from segment 1. Most defective RNAs possessed at least 178 nts from the 5' end of vRNA. The amount of 5' sequence present in those RNAs correlated with the segment of origin, suggesting that this was the minimum required for propagation of viral RNA in mouse lung and hence possibly for protection also.

Animals↗

PubMed1991

Influence of inoculum age on hybridoma culture kinetics.

To determine the influence of the inoculum age on the kinetics of hybridoma growth and metabolism, spinner flasks have been inoculated with cells previously propagated in T flasks for 43, 52, 62 and 71 hr respectively. Increasing the age of the inoculum is found to result in a longer lag phase, in a lower maximum specific growth rate and in a reduced maximal cell density. During the growth phase specific rates of glucose and glutamine uptake and of ammonia and lactate production are similar. However, with the older inoculum, much higher metabolic activities are observed during the lag phase. The production of antibodies is delayed with increasing inoculum age, but the final antibody concentrations are similar, which indicates a higher specific antibody production rate when inoculating with older cells.

Ammonia↗

PubMed1995

A rationale for the appropriate amount of inoculum in ready biodegradability tests.

Several screening methods at the so-called ready biodegradability level are suitable to test poorly soluble substances. Typical for these tests is that mineralization is evaluated from monitoring oxygen uptake or carbon dioxide production. Unfortunately, they suffer from a rather low precision in the calculated percentage of mineralization caused by subtracting a too high inoculum control measurement from the response in the test system. Criteria for blank oxygen consumption, due to the metabolic activity of the inoculum, are proposed from which maximum amounts of activated sludge or secondary effluent per litre test medium can be derived to be used as an appropriate inoculum. Both for current and future standardized tests the precision of the method can be kept within acceptable margins. Inoculum material was sampled from 40 communal biological waste water treatment plants. From endogenous respiration rates it was derived that the concentration of secondary effluent in the Closed Bottle Test can be increased up to 50 mL/L but that in respirometry tests inoculated with activated sludge the appropriate concentration is 10 mg/L dry matter or below, depending of the design of the test system.

Bacteria↗

PubMed1988

In vivo significance of the inoculum effect of antibiotics on Escherichia coli.

The minimum dosage of antibiotics which reduced mortality in rats intraperitoneally inoculated with an Escherichia coli isolate was determined. Low mortality rates (0-10%) were obtained when antibiotics with minimal or no inoculum effect (cefoxitin, cefmetazole and gentamicin) were administered to yield serum levels 3 to 20 times the MIC, while antibiotics with a pronounced inoculum effect (cefotaxime and aztreonam) had to be administered to yield serum levels 200 to 1,000 times the MIC determined with a standard (low) inoculum. Thus, it seems that the inoculum effect observed in vitro with some antibiotics for Escherichia coli may have clinical significance.

Animals↗

PubMed2005

Evidence for mutualist limitation: the impacts of conspecific density on the mycorrhizal inoculum potential of woodland soils.

The ability of seedlings to establish can depend on the availability of appropriate mycorrhizal fungal inoculum. The possibility that mycorrhizal mutualists limit the distribution of seedlings may depend on the prevalence of the plant hosts that form the same type of mycorrhizal association as the target seedling species and thus provide inoculum. We tested this hypothesis by measuring ectomycorrhizal (EM) fine root distribution and conducting an EM inoculum potential bioassay along a gradient of EM host density in a pinyon-juniper woodland where pinyon is the only EM fungal host while juniper and other plant species are hosts for arbuscular mycorrhizal (AM) fungi. We found that pinyon fine roots were significantly less abundant than juniper roots both in areas dominated aboveground by juniper and in areas where pinyon and juniper were co-dominant. Pinyon seedlings establishing in pinyon-juniper zones are thus more likely to encounter AM than EM fungi. Our bioassay confirmed this result. Pinyon seedlings were six times less likely to be colonized by EM fungi when grown in soil from juniper-dominated zones than in soil from either pinyon-juniper or pinyon zones. Levels of EM colonization were also reduced in seedlings grown in juniper-zone soil. Preliminary analyses indicate that EM community composition varied among sites. These results are important because recent droughts have caused massive mortality of mature pinyons resulting in a shift towards juniper-dominated stands. Lack of EM inoculum in these stands could reduce the ability of pinyon seedlings to re-colonize sites of high pinyon mortality, leading to long-term vegetation shifts.

Arizona↗

PubMed2006

Performance of a commercial inoculum for the aerobic biodegradation of a high fat content dairy wastewater.

The effectiveness of a commercial inoculum for degrading a dairy wastewater with high fat content was evaluated, and compared with an activated sludge inoculum from a dairy wastewater treatment pond. Both inocula reached similar chemical oxygen demand removal in batch experiments. The population dynamics was also studied by determining heterotrophic counts. Predominant microorganisms were differentiated by colony morphology and genomic fingerprinting (BOX-PCR) analysis. The higher population diversity and the wider range of CO2 production rate observed in batch reactors inoculated with activated-sludge, indicated that microorganisms from this inoculum were well adapted and may have had synergic activity for the degradation of the dairy effluent. When the bioreactor was operated with the commercial inoculum in continuous mode, according to its microbial growth kinetics, other microorganisms became predominant. These results showed that inoculated microorganisms did not persist in the open system and periodic addition of microorganisms may be needed to achieve a high performance treatment.

Animals↗

PubMed2000

Topical effects of cidofovir on cutaneous rabbit warts: treatment regimen and inoculum dependence.

The present study examined topical effects of cidofovir on cutaneous rabbit warts. Based on an inoculum-dependency study, each New Zealand White rabbit was inoculated with a high and low titer of cottontail rabbit papillomavirus (CRPV) at four sites on each dorsolateral area. Inoculation with 50 ID(50) induced papillomas at 100% of the inoculation sites within 16+/-1 days, and the wart growth curve plateaued within approximately 7 weeks. With an inoculum of 5 ID(50), 80% of the inoculated sites developed papillomas within 21+/-1 days and their size plateaued at a later time. Cidofovir was applied topically twice daily on the inoculated sites at a concentration of 1% for 18 days, starting at three different time points. In the first experiment, treatment was initiated 7 days post-inoculation. One of the inoculated sides received cidofovir or the vehicle, PBS, while the other side was left untreated. With this treatment regimen, cidofovir significantly delayed the time of onset and the growth rate of papillomas induced with the high titer of inoculum. It completely prevented papilloma-induction on the sites inoculated with the low titer of CRPV. Reversible side-effects of cidofovir were observed on the directly treated area including erythema, necrosis, and flaking. Both therapeutic and side-effects were limited to the sites of direct exposure. In the second experiment, one of the two sides in each group of rabbits received cidofovir or vehicle starting on day 29 post-inoculation. With this treatment regimen, cidofovir significantly reduced wart growth against the low titer only. Topical treatment initiated on day 49 post-inoculation was not effective on warts initiated with either viral titer. These results demonstrated that topical cidofovir could be very effective against papillomavirus-induced wart growth if it is initiated early during the infection, especially against low titers of inoculum.

Administration, Topical↗

PubMed2006

[Impact of subculture cycles and inoculum sizes on suspension cultures of Vitis vinifera].

The commercial application of plant cell cultures is often hindered by the instability of secondary metabolite biosynthesis, where the metabolite yield fluctuates and decline dramatically over subcultures. This study proposed that such instability is due to the fluctuations of culture variables. To validate this hypothesis, the effects of the fluctuations of two culture variables (subculture cycle and inoculum size) on the biomass, anthocyanin biosynthesig, intracellular carbon, nitrogen and phosphate during continuous 10 subculture cycles were investigated. The subculture cycle was fluctuated for 12h in a 7 day cycle (6.5, 7 and 7.5 d), and the inoculum size was fluctuated by 20% on basis of 2.00 g (1.60, 2.00 and 2.40 g). It was found that all the measured culture parameters fluctuated over the 10 subculture cycles. The fluctuation in terms of inoculum sizes had a greater effect on the stability of anthocyanin biosynthesis in suspension cultures of V. vinifera. Among all the subculture conditions investigated, 7d-subculture cycle and 1.60 g-inoculum size was the best one to hold the relatively stable anthocyanin production. The anthocyanin yield presented a negative correlation with intracellular sucrose content or intracellular total phosphate content.

Anthocyanins↗

PubMed1999

Inoculum effect leads to overestimation of in vitro resistance for artemisinin derivatives and standard antimalarials: a Gambian field study.

Artemisinin (QHS) and its derivatives are new antimalarials which are effective against Plasmodium falciparum parasites resistant to chloroquine (CQ). As these drugs are introduced it is imperative that resistance is monitored. In this paper we demonstrate that the inoculum size used in in vitro testing influences the measured in vitro susceptibility to QHS and its derivative dihydroartemisinin (DHA) and to mefloquine (MEF) and CQ over the range of parasitaemias routinely used in testing with the WHO in vitro microtest. An increase in parasitaemia and/or haematocrit was accompanied by a decrease in the measured sensitivity of 2 laboratory lines. In the context of a field study testing in vitro susceptibility of parasite isolates from patients with uncomplicated malaria in Fajara, The Gambia we demonstrate that failure to control for inoculum size significantly overestimates the level of resistance to QHS and DHA as well as MEF, halofantrine (HAL) and quinine (QUIN). When controlling for the inoculum effect, cross-resistance was observed between QHS, MEF and HAL suggesting the presence of a multidrug resistance-like mechanism. These studies underline the importance of inoculum size in in vitro susceptibility testing.

Animals↗

PubMed2004

Production of fumonisins by Fusarium verticillioides strains on solid and in a defined liquid medium--effects of L-methionine and inoculum.

In order to evaluate the toxicological and carcinogenic effects of fumonisins, large amounts of fumonisins need to be purified, which requires optimal conditions for production in culture. Five strains of F. verticillioides were compared for their ability to produce fumonisins in solid and liquid media with and without the addition of methionine, a fumonisin precursor. Inoculations were made either with lyophilized cultures or a concentrated inoculum. Growth in liquid medium, measured by biomass, was directly correlated to total fumonisin production when a lyophilized inoculum was used. Fumonisin production was stimulated by the addition of 0.2% L-methionine to solid media for most strains. Levels ranged from 1500-3900 mg/kg in rice, and 2900-12500 mg/kg in maize cultures inoculated with lyophilized cultures; 200-4800 mg/kg in rice, and 1500-4200 mg/kg in maize cultures inoculated with concentrated inoculum. Strains that produced relatively high levels of fumonisins in solid media did not necessarily do so in liquid medium and vice versa. Total fumonisin levels in liquid medium ranged from 40-590 mg/l inoculated with lyophilized cultures and < 1-110 mg/l inoculated with concentrated inoculum, without adding the precursor. F. verticillioides strains therefore varied in their ability to produce fumonisins, and conditions for production need to be optimized individually for each strain.

Biomass↗

PubMed1978

Influence of secondary inoculum of tumour cells on growth of primary tumour.

The effect of successive inocula of tumour cells given to rats at intervals of 1 to 10 days was examined. If W256 cells were injected on both occasions, the second inoculum failed to grow if given into the footpad as early as 1 day, or intravenously as soon as 4 days, after the first administration. However, although a second inoculum failed to grow, it produced significant augmentation of the growth of the primary implant if given during its latent or growth phases. If the second inoculum contained cells from a fibrosarcoma unrelated to W256, its growth was effectively curtailed if the initial inoculum had preceded it by 24 h or more. However, secondary inocula of fibrosarcoma cells did not augment the growth of the primary W256 tumour.

Animals↗

PubMed2000

Susceptibility testing: inoculum size dependency of inhibition using the Colworth MIC technique.

The minimum inhibitory concentration, MIC, is an accepted and well used criterion for measuring the susceptibility of organisms to inhibitors. Many factors influence the MIC value obtained, including temperature, inoculum size and type of organism. A modification of the method developed in this laboratory to obtain inhibition profiles of antimicrobials was used to examine the effect of inoculum size on the degree of inhibition observed with respect to inhibitor concentration. The data obtained enabled the production of an empirical model of inhibition, based on a Gompertz function, relating the level of growth observed to both the inoculum size and concentration of the inhibitor. The inoculum size dependencies of phenethyl alcohol, phenoxyethanol, p-chloro-m-cresol, trichloro-phenol, thymol and dodecyltrimethylammmonium bromide against Staphylococcus aureus were obtained.

Anti-Bacterial Agents↗