Initial Inoculum Density Research Articles

Frequency-dependent advantages of plasmid carriage by Pseudomonas in homogeneous and spatially structured environments

The conditions promoting the persistence of a plasmid carrying a trait that may be mutually beneficial to other cells in its vicinity were studied in structured and unstructured environments. A large plasmid encoding mercury resistance in Pseudomonas fluorescens was used, and the mercury concentration allowing invasion from rare for both plasmid-bearing and plasmid-free cells was determined for different initial inoculum densities in batch-culture structured (filter surface) and unstructured (mixed broth) environments. A range of mercury concentrations were found where both cell types could coexist, the regions being relatively similar in the two types of environment although density-dependent in the unstructured environment. The coexistence is explained in terms of frequency-dependent selection of the mutually beneficial mercury resistance trait, and the dynamics of bacterial growth under batch culture conditions. However, the region of coexistence was complicated by conjugation which increased plasmid spread in the mixed broth culture but not the structured environment.

Effects of sucrose, inoculum density, auxins, and aeration volume on ceil growth ofGymnema sylvestre

To improve the cell protocol forCymnema sylvestre, we investigated the influence of initial sucrose concentration, inoculum density, and optimal concentrations of auxins (IBA and NAA) in flask cultures, as well as the role of aeration volume in bioreactor cultures. Cell growth was enhanced 9-fold when the medium was supplemented with 3% sucrose versus a sucrose-free environment. Increasing the inoculum density to 60 g (wet weight) L-1, but no further, greatly improved the growth of these cultures. All concentrations of IBA proved inhibitory while supplementation with 5 nig L-1 NAA was associated with significantly higher dry-cell weights. In our bioreactor cultures, a step-wise increase in aeration volume from 0.05 to 0.40 wm was optimal for cell growth. Although biomass (i.e., fresh weight) accumulated in the bioreactor up until Day 20, the dry-cell weights increased 10-fold, but only through Day 15. The internal dynamics of our culture media indicated that sucrose was preferentially utilized and that its concentration steeply decreased at the log phase. In contrast, both glucose and fructose supplies were exhausted only at the beginning of the declining phase. Our findings suggest that a 15-d culture period is optimal for G.sylvestre cell growth in a bioreactor.

Production and partial characterization of dehairing protease from Bacillus cereus MCM B-326

Bacillus cereus MCM B-326, isolated from buffalo hide, produced an extracellular protease. Maximum protease production occurred (126.87 ± 1.32 U ml −1) in starch soybean meal medium of pH 9.0, at 30 °C, under shake culture condition, with 2.8 × 10 8 cells ml −1 as initial inoculum density, at 36 h. Ammonium sulphate precipitate of the enzyme was stable over a temperature range of 25–65 °C and pH 6–12, with maximum activity at 55 °C and pH 9.0. The enzyme required Ca 2+ ions for its production but not for activity and/or stability. The partially purified enzyme exhibited multiple proteases of molecular weight 45 kDa and 36 kDa. The enzyme could be effectively used to remove hair from buffalo hide indicating its potential in leather processing industry.

Epidemiology and integrated control of Nacobbus aberrans on tomato in Mexico

Abstract Population densities, population fluctuations, yield loss and disease incidence caused by Nacobbus aberrans on tomato (Lycopersicon esculentum) were studied, using an epidemiological approach, in a field experiment that included three different control regimes: an integrated control (IC) scheme, which included fertilisation, nematicide (ethoprop) and chicken manure; a technical control (TC) scheme, based on the best local practices of fertilisation and use of carbofuran for nematode control; and a check treatment (AC), with no application of fertilisers or nematicide. At least three generations of N. aberrans occurred through the cropping season and the numbers of galls/plant and females/g of root through the crop season were used to define the area under a disease progress curve (AUDPC). The variables b−1 (Weibull's apparent infection rate), AUDPC and Yf (final disease incidence) indicated less crop damage under the IC scheme than under the other two schemes (TC and AC). The IC scheme resulted in increased plant height (41-49%), foliage dry weight (37-53%) and stem diameter (31-41%) compared with the TC and AC schemes. Tomato yields in IC surpassed those from TC and AC by 34 and 83%, respectively, while TC exceeded AC by 73%. The yield loss attributed to N. aberrans was 12, 29 and 83% in IC, TC and AC, respectively. The IC scheme improved commercial production by 20 and 81% in comparison to the TC and AC schemes. This was largely due to effective control of the initial inoculum density, which affects the first generation of the nematode population; control of this generation is essential for avoidance of yield loss. The first generation is completed during the period 0-60 dat (days after transplanting), i.e., during the critical stages of flowering, fruit initiation and fruit set (40, 50 and 60 dat). Data on plant performance taken every 10 days were used to derive a multiple point model for calculation of production loss.

Influence of inoculum density of the antagonistic bacteria Pseudomonas fluorescens and Pseudomonas corrugata on sugar beet seedling colonisation and suppression of Pythium damping off

The effect of initial inoculum density of the antagonistic bacterial strains Pseudomonas fluorescens B5 and Pseudomonas corrugata 2140 (103 to 108 CFU per seed pellet) on sugar beet seedling colonisation, in situ bioluminescence and antagonistic activity towards Pythium ultimum was investigated. Populations of the bacteria colonising sugar beet root systems approached an apparent carrying capacity of 105 to 106 CFU per plant after 12 d growth, irrespective of inoculum density. This meant an up to 320-fold population increase at low inoculum densities and a decrease at high densities. Population densities of both bacteria and their corresponding in situ bioluminescence (resulting from luciferase enzyme expression from the inserted luxAB genes) reached highest levels in the hypocotyl region and in the upper root region 0–20 mm below seed level (104–106 CFU/cm section, 101–103 RLU/cm section) and decreased with root depth. In situ bioluminescence, which indicates physiological activity, was measurable at lowest antagonist initial inoculum density (103 CFU per seed pellet) and did not increase significantly with increasing inoculum density. Bioluminescence was also significantly correlated with population density. For Pseudomonas fluorescens B5, the total population size per plant and downward colonisation of the root (below 40 mm depth) increased significantly with antagonist inoculum density applied to the seeds. For Pseudomonas corrugata 2140, no significant influence of initial inoculum density on root colonisation was observable. Survival and dry weight of sugar beet seedlings in Pythium infested soil increased significantly with increasing inoculum density of Pseudomonas fluorescens B5, whereas for Pseudomonas corrugata 2140, initial densities of 104 to 106 CFU per seed resulted in maximal survival of plants.

Field Isolates of Streptomyces Differ in Pathogenicity and Virulence on Radish.

Common scab is a significant disease of potato, and affects root and tuber crops worldwide. Streptomycetes, a diverse group of soil-inhabiting gram-positive bacteria, cause common scab. To better understand the basis for variability in disease symptoms seen in field situations, strep-tomycetes were isolated from scabby potato plants. Isolates differed in morphology and pigmentation. Isolates were evaluated for pathogenicity and virulence in radish. Scab lesions varied in appearance and severity. Disease symptoms also included plant stunting, wilting, necrosis, and death. Some pathogenic isolates were missing genes from the putative pathogenicity island (PAI); several lacked the nec1 gene, and one was missing the txtA gene encoding thaxtomin biosynthesis, the most reliable pathogenicity determinant. Studies of disease severity over 5 logs initial inoculum density showed that there is a threshold inoculum density for disease. Disease severity increased with inoculum density over three logs, then reached a maximum, which is characteristic of individual Streptomyces strains. Lesion severity was not correlated with presence of melanin, the nec1 gene, or whether an isolate reduced seedling emergence or plant survival. Differences in disease symptoms and severity combined with absence of known pathogenicity determinants (txtA) or factors (nec1) suggest that there may be pathogenicity factors in addition to thaxtomin.

Temporal and Spatial Dynamics of Primary and Secondary Infection by Armillaria ostoyae in a Pinus pinaster Plantation

ABSTRACT Epidemiological investigations were performed in a 3-ha maritime pine (Pinus pinaster) plantation established on a site heavily infested by Armillaria ostoyae. Geostatistics were used to examine the density and the distribution of the initial inoculum. Disease dynamics were monitored for 17 years after planting. On the whole site, the cumulative mortality rate reached 35% over this period, plateauing at 12 years. Disease progress curves differed according to the density of the initial inoculum, although in all the cases, the Gompertz model described the epidemics well. The epidemiological contributions of both primary (initially colonized stumps) and secondary inoculum (newly dead pines) were evaluated by analyzing their spatial relation to annual mortality. Newly dead pines acted as secondary inoculum from year 3 and their role increased with time. When the initial inoculum density was low, the contribution of secondary inoculum to epidemic development increased faster and halted sooner than when the density of primary inoculum was high. Regardless of its density, the primary inoculum acted throughout the dynamic phase of the epidemic. When the inoculum density was low, the probability of mortality during the first 6 years of the epidemic depended on the tree distance from the nearest stumps colonized by Armillaria sp. When the inoculum density was high, the probability of mortality was higher and not related to the distance between trees and colonized stumps.

New citrus selections from Cleopatra mandarin × Poncirus trifoliata with resistance to Tylenchulus semipenetrans Cobb

AbstractThe response of four resistant selections of Cleopatra mandarin × Poncirus trifoliata to increasing inoculum densities of a population of the Mediterranean biotype of Tylenchulus semipenetrans was determined in microplots established at two sites. One-yearold trees of the resistant selections and of a susceptible Carrizo citrange were inoculated with 0, 1, 5 or 10 × 104 eggs per plant (Pi). Nematode reproduction on the resistant selections was consistently less than on Carrizo citrange. Increasing initial inoculum densities had no effect on the relative resistance in three selections (03.01.42, 03.01.5 and 03.01.16). Selection 03.01.42 was highly resistant (no females and eggs per g fresh root), and 03.01.5 and 03.01.16 both had good resistance (≤15% as many females and eggs per g fresh root as on Carrizo citrange). The fourth selection (03.01.18) expressed resistance at Pi 1 and 5 × 104 eggs per plant but was moderately susceptible at 10× 104 eggs per plant (>15% females and eggs per g fresh root). Deposits of a lignin or suberin-like material were more abundant in resistant selections 03.01.5 and 03.01.18 than in susceptible Carrizo citrange. The proportional increase in trunk diameter of inoculated and uninoculated trees of each rootstock was similar at both sites.

Ascocarp formation and survival and primary inoculum production in Erysiphe (sect. Microsphaera) pulchra in dogwood powdery mildew

SummaryDevelopment of powdery mildew Erysiphe (sect. Microsphaera) pulchra in dogwood (Cornus florida) was assessed over a 5‐year period (1996–2000). Variations in the timing of initial infection, disease severity, ascocarp formation, and primary inoculum density were evaluated. Ascocarps formed late in the growing season (September‐November) when relatively low temperatures (< 27°C) persisted for at least 2 weeks, but ascocarp abundance was not influenced by disease severity. Studies conducted in a controlled environment showed that low temperatures triggered ascocarp formation and neither day length nor host plant age affected ascocarp formation. Ascocarps formed within 12–14 days at 18°C/ 10°C (day/night) and 23°C/15°C, but required 25 days at 26°C/18°C; no ascocarps formed at 28°C/ 20°C. Because ascocarps are an important source of primary inoculum for dogwood powdery mildew, ascocarp survival was evaluated in a 2‐year study (1998–2000). 60–80% of mature, dark‐coloured ascocarps survived at ‐10°C and ‐20°C and maintained viable spores for 4 months, but only 4–12% of partially developed, light brown ascocarps survived at ‐10°C and ‐20°C in the first experiment and only 30–40% survived in the second experiment. Immature ascocarp initials (cream‐yellow in colour) withered and disintegrated at all temperatures (24°C/20°C, 4°C, ‐10°C, and ‐20°C). Because ascocarps need time to mature, the timing of ascocarp initiation affects ascocarp maturity and thus winter survival and primary inoculum density. The evaluation of spring inoculum dispersal to spore traps and trap plants in 1999 and 2000 showed that rainfall patterns in early spring influenced primary inoculum and thus the timing of initial infection.

Wheat Straw Mulch and Its Impacts on Three Soilborne Pathogens of Peanut in Microplots.

Experiments were conducted in 1992, 1993, and 1994 to determine the effects of surface residue on incidence of Cylindrocladium black rot (CBR), Sclerotinia blight, and Southern stem rot of peanut in microplots in North Carolina. Soil was infested with either Cylindrocladium parasiticum, Sclerotium rolfsii, or Sclerotinia minor and plots were planted with the peanut cultivars NC 7 or NC 10C. Wheat straw was applied to establish 80 to 90% soil-surface coverage. Disease incidence data were collected every 2 weeks in 1992 and weekly in 1993 and 1994. Southern stem rot incidence did not increase with straw amendment but final inoculum density of Sclerotium rolfsii was highest in straw-amended plots. Straw amendment enhanced CBR incidence in 1992, but had minimal effects in 1993 and 1994. Neither root rot severity nor inoculum density of C. parasiticum was affected by straw treatment. Straw application reduced Sclerotinia blight in 1992 and 1993 but not in 1994 compared with unamended plots. Initial inoculum density had the greatest impact on final Sclerotinia minor populations. Soil temperature and moisture were monitored in 1993 and 1994. Soil at 0 to 2 cm of depth in strawamended microplots was 1 to 2°C cooler than in unamended plots.

Effect of a Single or Double Soil Solarization to Control Verticillium Wilt in Established Olive Orchards in Spain.

Four soil solarization experiments were completed in three commercial olive orchards infested with Verticillium dahliae in southern Spain. Three of the experiments used lines of trees and one used individual plants. Plantations had different initial inoculum densities of the pathogen. Initial studies indicated that highly virulent (cotton-defoliating) isolates of the pathogen were present in Marinaleda (experiment I), which represents the first record of such isolates affecting olive trees in Europe. Solarization treatments were applied to lines of trees for either one (single) or two consecutive (double) years. Solarization significantly reduced pathogen populations in the top 20 cm of soil for at least 3 years in relation to control plots. Pathogen reduction after the single solarization obscured effects of the second solarization treatment. Decrease of inoculum density in soil by solarization did not correspond to a similar reduction in disease severity. Disease severity was reduced only in orchards with medium or high initial inoculum densities. A second soil solarization treatment did not improve the effect of single solarization on Verticillium wilt control. In orchards with low inoculum densities, soil solarization did not result in significant differences in disease incidence and severity, but improved recovery of trees from the disease. Soil-solarized plots remained free of weeds, but tress in solarized plots did not show significant growth increase measured by trunk perimeter.

Population Dynamics of Fusarium Oxysporum f. Sp. Radicis-lycopersici in Relation to the Onset of Fusarium Crown and Root Rot of Tomato

Fusarium oxysporum f. sp. radicis-lycopersici the causal agent of crown and root rot in tomato comprises two overlapping separate phases: monocyclic and polycyclic. Oversummering inoculum is the source of primary infection (the monocyclic phase) and the spread from plant to plant via root-to-root contact is the source of the secondary infection (the polycyclic phase). In the present work, relationships between initial inoculum density, population dynamics of the pathogen in the root zone of diseased plants, and disease onset were studied. For the monocyclic phase, 55.1% of the variance of disease onset was attributed to the rate of pathogen proliferation in the root zone of plants, and only 12.8% of the variance was attributed to the amount of initial inoculum density. For the polycyclic phase, disease onset was not related to either initial inoculum density or the rate of pathogen proliferation in the root zone. At disease onset, the inoculum density of the pathogen in the root zone of plants infected from oversummering inoculum reached an average of 4.08 log cfu g soil−1. The inoculum density of the pathogen in the root zone of plants infected by their diseased neighbors was 3.23 log cfu g soil−1. A large variation in pathogen proliferation rate in the root zone was found among individual plants, suggesting that differences in the level of soil suppressiveness may occur not only between fields, but even in the same field over short distances.

Effects of preplant inoculation of apple (Malus domestica Borkh.) with arbuscular mycorrhizal fungi on population growth of the root-lesion nematode, Pratylenchus penetrans

Six species of arbuscular mycorrhizal (AM) fungi (Glomus aggregatum, G. clarum, G. etunicatum, G. intraradices, G. mosseae and G. versiforme) were evaluated, in three greenhouse experiments, for their effects on reproduction of the root-lesion nematode, Pratylenchus penetrans, and growth of Ottawa 3 apple rootstock. Glomus mosseae increased total dry weights of nematode-inoculated and non-inoculated rootstock in all three greenhouse experiments, and G. intraradices increased dry weights in two of three greenhouse experiments. Plants inoculated with G. mosseae generally supported fewer P. penetrans per gram of root than plants inoculated with other AM fungi, but did not differ significantly from the controls in any greenhouse experiment. Colonization of roots by AM fungi was reduced by P. penetrans at initial inoculum densities greater than 250 nematodes/L soil. In field trials, preplant inoculation with either G. intraradices or G. mosseae increased rootstock growth and leaf concentrations of P, Mg, Zn and Cu in fumigated plots but not in non-fumigated plots, indicating that colonization by native AM fungi in non-fumigated plots may have been sufficient for adequate nutrient acquisition. The abundance of vesicles and arbuscules was greater in roots of plants inoculated with AM fungi before planting than in roots of non-inoculated plants, in both fumigated and non-fumigated plots. P. penetrans per gram of root and per 50 ml soil were significantly lower for G. mosseae- inoculated plants than for non-inoculated plants in fumigated soil but not in non-fumigated soil.

Substrate Concentration and Plasmid Transfer Frequency between Bacteria in a Model Rhizosphere.

The influence of substrate concentration on plasmid transfer frequency in the rhizosphere was investigated using a physical model employing a hollow fiber membrane instead of a real root. The absolute number of transconjugants produced increased with increasing substrate (glucose) concentration, but the plasmid transfer frequency decreased exponentially with increasing substrate concentration from 4.4 × 10(-3) at 90 μg ml(-1) glucose to 1.35 × 10(-5) at 3600 μg ml(-1) glucose. These results were found to be heavily dependant on donor to recipient ratio and distribution of strains, but independent of initial donor and recipient inoculum density and regime. These observations also show that plasmid transfer frequency is reduced at high substrate concentrations, which suggests that plasmid transfer is either stimulated when growth limiting nutrient is scarce or inhibited when it is abundant.

Functional substrate biodiversity of cultivated and uncultivated A horizons of vertisols in NW New South Wales

Concern over the effects of anthropogenic activities on soil ‘quality’ has fuelled efforts to identify and measure those factors that affect soil quality. Soil microbial diversity is one of many possible factors. Our objective was to compare the functional diversity of microbial communities in the A horizons of cultivated and uncultivated vertisols in NW New South Wales. Samples from two cultivated and two uncultivated sites were tested using the community level physiological profiles (CLPP) method. Substrate richness, the rate of substrate use and the diversity of substrate use, as measured by the Shannon index, were significantly larger in the uncultivated sites than in the cultivated sites. The CLPP also indicated a higher rate of substrate use in the uncultivated sites, although this may have been due to greater initial inoculum densities. When diversity values for each site were compared with several soil physical and chemical properties, a relationship between organic carbon and functional diversity was apparent. The fit to a broken-stick model showed that diversity increased up to 1.76% organic carbon and remained constant above that value. The implications of these results for soil quality will depend upon future investigations on the significance of soil microbial diversity as a component of soil quality.

Dynamics of Primary and Secondary Infection in Take-All Epidemics

ABSTRACT Using a combination of experimentation and mathematical modeling, the effects of initial (particulate) inoculum density on the dynamics of disease resulting from primary and secondary infection of wheat by the take-all fungus, Gaeumannomyces graminis var. tritici, were tested. A relatively high inoculum density generated a disease progress curve that rose monotonically toward an asymptote. Reducing the initial inoculum density resulted in a curve that initially was monotonic, rising to a plateau, but which increased sigmoidally to an asymptotic level of disease thereafter. Changes in the infectivity of particulate inoculum over time were examined in a separate experiment. Using a model that incorporated terms for primary and secondary infection, inoculum decay, and host growth, we showed that both disease progress curves were consistent with consecutive phases dominated, respectively, by primary and secondary infection. We examined the spread of disease from a low particulate inoculum density on seminal and adventitious root systems separately. Although seminal roots were affected by consecutive phases of primary and secondary infection, adventitious roots were affected only by secondary infection. We showed that the characteristic features of disease progress in controlled experiments were consistent with field data from crops of winter wheat. We concluded that there is an initial phase of primary infection by G. graminis var. tritici on winter wheat as seminal roots grow through the soil and encounter inoculum, but the rate of primary infection slows progressively as inoculum decays. After the initial phase, there is an acceleration in the rate of secondary infection on both seminal and adventitious roots that is stimulated by the increase in the availability of infected tissue as a source of inoculum and the availability of susceptible tissue for infection.

Effects of Soil Fumigation and Flooding on Suppression of Pythium Root Rot in Ornamental Bulb Culture

The effects of flooding and soil fumigation with cis-dichloropropene or methylisothiocyanate (MIT) on disease suppression against Pythium spp. were tested in pot and field experiments in sandy soil. Disease suppression was reduced by both flooding and fumigation treatments, resulting in severe infection in Iris and Crocus and reduction of bulb yields. It is demonstrated that the disease suppression has a biological nature, and that disease severity is more related to effects of the soil treatments on the soil microflora than to the initial inoculum density of Pythium. After flooding, disease suppression was restored within the experimental period of two years, whereas after fumigation, disease suppression was only partially restored. The effect of repeated fumigation in two consecutive years on the disease suppression was less severe than the effect of a single fumigation treatment prior to cultivation of a susceptible crop.

Effect of Meloidogyne incognita on Hyoscyamus muticus

ABSTRACT The influence of different initial inoculum densities of Meloidogyne incognita on growth of henbane (Hyoscyamus muticus), total alkaloid concentration, physiological and biochemical changes, root-knot development, and nematode multiplication was investigated 60 days after inoculation in a glasshouse. A negative correlation was noted between initial inoculum densities and various growth variables. The greatest reduction in growth occurred in plants inoculated with the highest density of nematodes (15,000 juvenile/stage 2 organisms/5 kg soil). The highest reproduction factor was observed in plants inoculated with the lowest level of nematode population tested (50 juvenile/stage 2 organisms/5 kg soil).

Quantitative detection of pentachlorophenol-degrading Sphingomonas sp. UG30 in soil by a most-probable-number/polymerase chain reaction protocol

Traditionally, biodegradation of pentachlorophenol (PCP) in soil is studied by disappearance of the parent compound and its intermediates. Because of the lack of methods to enumerate PCP-degrading bacteria in environmental samples, little is known about the dynamics of these organisms in soil. In this study, the efficiency of a modified most-probable-number/polymerase chain reaction (MPN/PCR) protocol was compared to the traditional MPN/[ 14C]PCP mineralization assay to quantify the density of PCP-degrading Sphingomonas sp. UG30 cells inoculated in an agricultural soil. A 753-bp tetrachlorohydroquinone reductive dehalogenase gene ( pcpC) fragment of UG30 was targeted for the MPN/PCR amplification. The MPN/PCR protocol had a detection limit of 3 CFU/g dry soil. A good correlation was established between the MPN/PCR estimations and initial inoculum densities ranging from 30 to 2×10 9 CFU/g of soil. However, the MPN/[ 14C]PCP mineralization protocol underestimated the inoculum density by 70 to 740-fold. Survival of UG30 in soil was monitored by the MPN/PCR assay. Cell density of the UG30 inoculum decreased from 1.8×10 8 to 1.9×10 5 cells/g of soil in the first 20 days of incubation and stabilized at 1.9×10 4 cells/g of soil after 50 days. When the soil was autoclaved prior to inoculation, UG30 cell density remained at 6.7×10 7 cells/g of soil after 50 days of incubation.

Mineralization of pentachlorophenol in a contaminated soil by Pseudomonas sp UG30 cells encapsulated in ?-carrageenan

A contaminated soil from Ontario, Canada containing 350–370 ppm pentachlorophenol (PCP) and 21000 ppm total petroleum hydrocarbons (TPH) was inoculated with PCP-degrading Pseudomonas sp UG30 cells either encapsulated in κ κ-carrageenan or as free cells. Uninoculated control soil produced 18.8 ± 3.9% of 14CO2 from 100000 dpm [U-14C]-PCP after 30 weeks incubation at 22°C. Addition of phosphate increased PCP mineralization, whereas addition of nitrogen inhibited mineralization almost completely in soil not inoculated with UG30 cells. No enhancement of mineralization was observed in soil with the addition of 108 CFU g−1 dry soil free UG30 cells. κ κ-Carrageenan-encapsulated UG30 cells at the same inoculum density mineralized 64.7 ± 0.3% PCP in soil after 26 weeks. Repeated inoculations with encapsulated UG30 cells up to six times over 6 weeks resulted in 64.8 ± 1.9% mineralization of radiolabelled PCP within 9 weeks, although by 12 weeks all treatments with encapsulated cells had mineralized to this level. Addition of sterile beads (controls) led to less than 16.6 ± 9.2% mineralization within 16 weeks. Varying initial inoculum densities of encapsulated cells were compared to determine effects on PCP mineralization. Cells grown inside the beads, and higher initial cell densities exhibited greater mineralization activity in the first weeks, but by 20 weeks PCP mineralization was approximately 70.0 ± 8.0% and was not significantly different between all soil treatments. Our results show encapsulation can enhance pollutant mineralization in a chemically contaminated soil.