Antifungal activity of some plant extracts on some pathogenic fungi

The inhibitory activity of five plant extracts viz. Artemisia absinthium L., Rumex obtusifolius L., Taraxacum officinale Weber ex Wiggers, Plantago lanceolata L. and Malva sylvestris L. were evaluated against the mycelial growth of three fungi Alternaria alternata (Fr.) Keissler, Penicillium expansum Link ex Thom. and Mucor piriformis Fisher that cause rot diseases in fruits and vegetables resulting in low yield and quality of fruits and vegetables. Results revealed that all the concentrations of plant extracts brought about significant inhibition in the mycelial growth of these pathogenic fungi. However, the highest concentration caused maximum inhibition in the mycelial growth followed by lower concentrations of plant extracts. The extract of A. absinthium leaves at highest concentration (S) proved highly effective in inhibiting the mycelial growth of all these pathogenic fungi followed by other plant extracts. These plants thus may have potential as the new natural fungicide for management of fungal rot diseases.     

GROWTH-INFLUENCING SUBSTANCES IN SEDIMENT EXTRACTS FROM A SUBTROPICAL WETLAND: INVESTIGATION USING A DIATOM BIOASSAY1

A Biological assay using Amphora coffeaeformis var. perpusilla (Grunow) Cleve and A. coffeaeformis (Agardh) Kützing was used to investigate the changes in the properties of soluble organic carbon in sediments taken from a coastal wetland. During January to May, sediment extracts became increasingly inhibitory to diatom growth After the onset of the spring rains, the inhibitory properties of the extracts disappeared. Substances capable of promoting mixotrophic growth and heterotrophic growth were found in extracts taken in July to December. These positive responses took place at the time of mangrove (Rhizophora mangle L.)leaf-fall.     

Effect of Chrysanthemum Plant Extract on Flower Initiation in Short-Day Plants

An extract was prepared from Chrysanthemum plants in flower. It was separated into eight different fractions putting emphasis on the sterol components of the extracts. Fractions 5 and 6 were found to contain active substance (s), which to some extent, brought about floral bud initiation in both Chrysanthemum and Xanthium. The active substance (s) present in the above two fractions might be a sterol (s), similar to those of sitosterol and stigmasterol or other related compounds. Gibberellic acid brought about stem elongation as usual, but was found ineffective in causing any tissue differentiation in both Chrysanthemum and Xanthium. Investigations are underway to separate and identify the different compounds present in fractions 5 and 6. The effects of these compounds on test plants, both individually and in combinations, might provide some valuable information as to the nature of the flowering hormone.     

本氏针茅根际土提取物对本氏针茅及其优势种种子萌发的影响

以本氏针茅及其优势种大针茅和百里香种子为受体,采用生物检测的方法研究了0(对照)、0.1、0.2和0.5g/mL本氏针茅根际土甲醇浸提液和水浸提液对3种受体种子萌发的影响,以探究草地演替过程中物种间的生态关系和化感作用的表现形式。结果显示:(1)甲醇浸提液对3种受体种子的发芽均有抑制作用;水浸提液对本氏针茅发芽有促进作用,对百里香有部分促进作用,而对大针茅有抑制作用。(2)甲醇浸提液对本氏针茅和大针茅胚根和胚芽生长无显著影响,而抑制百里香胚根和胚芽的生长;水浸提液对本氏针茅胚根生长无显著影响,对本氏针茅胚芽生长具有显著促进作用,而对其它两种受体胚根和胚芽均无显著影响。(3)各种浓度甲醇浸提液对大针茅和百里香生长表现出了化感综合抑制效应,对本氏针茅生长于0.2g/mL时表现出化感综合抑制效应,其它2种浓度(0.1、0.5g/mL)表现为化感综合促进效应;水浸提液对本氏针茅和百里香表现为化感综合促进效应,而对大针茅表现为化感综合抑制效应。研究表明,本氏针茅根际土甲醇浸提液和水浸提液的化感物质存在差异;不同受体对同一浸提液反应不同,同一受体对不同浸提液的反应也不同。     

Stimulation ofBradyrhizobium japonicum by allelochemicals from green plants

Yeast extract-mannitol broth supplemented with 3 mg.ml⁻¹ extract from aerial parts of plants was noculated withB. japonicum 3I1b110. Filter-sterilized water extracts of foxtail (Setaria viridis), lambsquarters (Chenopodium album), Johnsongrass (Sorghum halepense) and Pennsylvania smartweed (Polygonum pensylvanicum) stimulated growth of the bacterium by 3–4 times after 48 h incubation; however, similar extracts from several other plants were marginally stimulatory. Autoclaved water extracts and methanol (75%) extracts were less stimulatory than filter-sterilized water extracts. Autoclaved water extracts of nutsedge (Cyperus esculentus) and ragweed (Ambrosia psilostachya), and methanol extracts of smartweed, peat and ragweed depressed growth of the bacterium. Filter-sterilized water extracts from shoots of foxtail and lambsquarters increased growth of the bacterium linearly up to 6 mg.ml⁻¹. At that level growth in the presence of lambsquarters shoot extract was almost 20 times that of the control. Comparable growth stimulation by this extract was also found in four other strains ofB. japonicum. The water extracts from roots and stems of lambsquarters, and roots, shoots and inflorescences of foxtail at 3 mg.ml⁻¹ stimulated growth of the bacterium by more than 40 times the control.     

Allelochemicals produced by Caribbean macroalgae and cyanobacteria have species-specific effects on reef coral microorganisms

Coral populations have precipitously declined on Caribbean reefs while algal abundance has increased, leading to enhanced competitive damage to corals, which likely is mediated by the potent allelochemicals produced by both macroalgae and benthic cyanobacteria. Allelochemicals may affect the composition and abundance of coral-associated microorganisms that control host responses and adaptations to environmental change, including susceptibility to bacterial diseases. Here, we demonstrate that extracts of six Caribbean macroalgae and two benthic cyanobacteria have both inhibitory and stimulatory effects on bacterial taxa cultured from the surfaces of Caribbean corals, macroalgae, and corals exposed to macroalgal extracts. The growth of 54 bacterial isolates was monitored in the presence of lipophilic and hydrophilic crude extracts derived from Caribbean macroalgae and cyanobacteria using 96-well plate bioassays. All 54 bacterial cultures were identified by ribotyping. Lipophilic extracts from two species of Dictyota brown algae inhibited >50% of the reef coral bacteria assayed, and hydrophilic compounds from Dictyota menstrualis particularly inhibited Vibrio bacteria, a genus associated with several coral diseases. In contrast, both lipo- and hydrophilic extracts from 2 species of Lyngbya cyanobacteria strongly stimulated bacterial growth. The brown alga Lobophora variegata produced hydrophilic compounds with broad-spectrum antibacterial effects, which inhibited 93% of the bacterial cultures. Furthermore, bacteria cultured from different locations (corals vs. macroalgae vs. coral surfaces exposed to macroalgal extracts) responded differently to algal extracts. These results reveal that extracts from macroalgae and cyanobacteria have species-specific effects on the composition of coral-microbial assemblages, which in turn may increase coral host susceptibility to disease and result in coral mortality.     

Gracilaria conferta and its epiphytes: 3. Allelopathic inhibition of the red seaweed byUlva cf.lactuca

In a previous study (Svirski et al., 1993), it was found that growth inhibition ofGracilaria spp., when cultured in the presence ofUlva cf.lactuca, was not due to shading or nutrient depletion, but seemed to be caused by competition for inorganic carbon or some type of allelopathy. In the present study, we attempted to differentiate between these two possible influences by (1) growing the two algae in biculture under various conditions, but keeping inorganic carbon levels constant and measuring net photosynthesis, respiration and growth rates, and by (2) measuring growth rates ofGracilaria spp. in the presence of extracts derived from media previously used to growUlva cf.lactuca.Both net photosynthesis and growth rates ofGracilaria spp. in biculture were inhibited, despite CO₂ (and also HCO₃ ^–) levels being kept constantly high in the culture media. It is likely that these responses were due to markedly enhanced rates of dark respiration inGracilaria spp. when grown together withUlva cf.lactuca. Growth ofGracilaria spp. was also inhibited by extracts derived from seawater in whichUlva cf.lactuca had previously been grown. The strong inhibition by ethyl acetate and chloroform extracts indicate an allelopathic effect onGracilaria spp.     

Allergenic evaluation of Malassezia furfur crude extracts

Crude extracts of the lipophilic yeast Malassezia furfur were obtained from 2, 6, 10 and 28 day old cultures. The in vitro cultivation periods corresponded, respectively, to the lag phase, middle of the log phase, end of log phase and the decline phase of the growth curve, which was based on viable cell counts obtained with a fluorescent viability test. Biochemical analyses showed that the protein and carbohydrate contents were greater in day 10 extracts. Seventy patients with different allergic manifestations and 30 healthy volunteers were skin prick tested using the extracts. Of these, thirteen (18.57%) patients gave positive responses. SDS PAGE gradient electrophoretic profiles of the preparations indicated that the 28 day extracts contained the greatest number of protein bands with molecular weights ranging mostly between 30 and 94 kDa. Immunoblots incubated with individual patient sera showed that four IgE binding M. furfur allergens of approximately 88, 61, 52 and 39 kDa were present in the 28 day extracts. The components identified could be used for detecting IgE mediated responses to M. furfur among individuals affected with different allergic conditions.This revised version was published online in October 2005 with corrections to the Cover Date.     

Cordeauxia edulis and Rhododendron tomentosum extracts disturb orientation and feeding behavior of Hylobius abietis and Phyllodecta laticollis

The use of plant‐based compounds to control insect pests is an alternative to the use of synthetic pesticides. We evaluated the repellent and antifeedant effects of Cordeauxia edulis Hemsley (Fabaceae) and Rhododendron tomentosum Harmaja (Ericaceae) extracts against Hylobius abietis L. (Coleoptera: Curculionidae) and Phyllodecta laticollis Suffrian (Coleoptera: Chrysomelidae). Repellent properties were evaluated by monitoring responses of adult insects toward the odor from extracts or extraction solvents (controls) in a Y‐tube olfactometer, and choice or no‐choice feeding tests were conducted by applying extracts or extraction solvents on stems of Scots pine [Pinus sylvestris L. (Pinaceae)] and European aspen [Populus tremula L. (Salicaceae)], host plants of H. abietis and P. laticollis, respectively. Extracts of R. tomentosum repelled adults of both insect species effectively. However, extracts of C. edulis did not repel H. abietis although its ethyl acetate extract showed repellence against the adults of P. laticollis. Feeding by H. abietis was significantly reduced by a methanol extract of C. edulis, and methanol and hexane extracts of R. tomentosum. Feeding by the adults and larvae of P. laticollis was significantly reduced by extracts from both plant species. Concomitant with less feeding, larval growth was retarded by ethyl acetate extracts of both plant species. Gas chromatography‐mass spectrometry analyses of the volatile components of the extracts showed that extracts from both plant species were mixtures of various terpene and non‐terpene compounds, which showed quantitative and/or qualitative variations between plant species and extraction solvents. This experiment showed that extracts from both plant species effectively manipulated the orientation and/or feeding behavior of the two beetle species. Hence, they may be considered as potential alternatives to synthetic chemical pesticides.     

Monoenyl hydrocarbons in female body wax of the yellow peach moth as synergists of aldehyde pheromone components

The non-polar components of female body wax and pheromone gland extracts of the yellow peach moth synergistically enhanced male behavioral responses from close to pheromone sources in wind tunnel tests when mixed with an aldehyde pheromone blend. When the non-polar fractions (NPFs) of female body wax were further separated by column chromatography, synergistic activities were found in the 3 and 50% ether in hexane fractions, and they additively increased male responses. The main components of the first fraction were (Z)-9-tricosene, (Z)-9-pentacosene, (Z)-9-heptacosene, (Z)-9-nonacosene and (Z)-9-hentriacontene. Only (Z)-9-heptacosene showed a significant synergistic effect in enhancing male responses, but the other components had no effect. A mixture of the five monoenyl hydrocarbons lost activity at lower doses than 5 ng. Natural ratios of these hydrocarbons in the female body wax and pheromone gland extracts were similar, but the amount of (Z)-9-heptacosene in the female body wax was significantly higher than in the pheromone gland extracts. We conclude that (Z)-9-heptacosene increases male responses to aldehyde pheromones, and unknown component(s) in the 50% ether in the hexane fraction are required for full synergistic enhancement by the NPFs of the female body wax and the pheromone gland extracts.     

黄土丘陵区草本群落演替中先锋种群茵陈蒿浸提液的化感作用

为探索自然演替中植被群落结构与化感作用之间的关系,以黄土丘陵区自然演替中先锋种群茵陈蒿为研究对象,通过种子萌发试验,分析演替初期优势种群茵陈蒿浸提液(甲醇浸提液和水浸提液)对自身以及伴生种种子萌发以及幼苗生长的影响,从化学生态学角度解释演替初期群落结构形成的原因。结果表明,茵陈蒿浸提液对3种伴生种(铁杆蒿、白羊草和达乌里胡枝子)的种子萌发均有显著化感作用,低浓度(0.002g/m L)时表现为促进或轻微的抑制作用,高浓度(0.2g/m L)时为较强的抑制作用;不同部位茵陈蒿浸提液的化感作用不同,相比之下,地上部的抑制作用更为强烈,其浸提液均抑制铁杆蒿、白羊草和达乌里胡枝子的种子萌发,尤其在浓度为0.2 g/m L时,达到完全抑制;根系甲醇浸提液对铁杆蒿种子萌发的抑制作用要强于同浓度下的水浸提液,而地上部水浸提液对受体植物根芽的作用大于甲醇浸提液。茵陈蒿对于自身具有一定的抑制作用,表现为高浓度(0.2和0.02 g/m L)的水和甲醇浸提液抑制自身种子萌发和幼苗生长。研究结果说明化感作用可能是该地区在演替前期形成以茵陈蒿为优势种植被群落的重要原因之一。创新点:从化学生态学的角度解释了黄土丘陵区植被演替初期植物之间的关系以及群落结构形成的原因,为认识自然恢复的内在机理提供了新的视角。     

Impairment of inulin assimilation and β-fructosidase activity due to a petite mutation in Kluyveromyces marxianus

A respiratory deficient mutant of Kluyveromyces fragilis was isolated using ethidium bromide mutagenesis. It was characterized by a loss of cytochromes a+a3 and deficiency in cytochrome b. This petite mutant has brought about modifications in the excretion pattern of -fructosidase active on saccharose and inulin. The mutant practically no longer excretes the enzyme, and is incapable of growth and fermentation in the presence of inulin. The study of the activities of different enzyme extracts (culture medium, whole and disrupted cells) on inulin and saccharose suggests the existence of an unique enzyme system capable of taking several form, and also shows the influence of the growth substrate on the I/S activity ratio.     

In vitro evaluation of Colombian plant extracts against Black Sigatoka (Mycosphaerella fijiensis Morelet)

In this work, 90 dichloromethane and methanol extracts obtained from 45 plants collected at the Natural Reserve Bremen – La Popa (Colombia) and at the Natural Regional Park Ucumarí (NRPU, Colombia) belonging to five botanical families were evaluated at 1000 mg/l, for their in vitro fungicide activity through the ascospore germ tube elongation and the measurement of the mycelial radial growth of Mycosphaerella fijiensis assays. The methanol extracts from the species Lycianthes acutifolia (Solanaceae) and Piper pesaresanum (Piperaceae); as well as, the dichloromethane extracts from P. pesaresanum and those from the Lauraceae family named Nectandra acutifolia and Ocoteca paulii, all inhibited M. fijiensis ascospore germination in 100% in the germinative tube elongation assay. With regards to the effects of the plant extracts on mycelial radial growth, the methanol extracts from P. pesaresanum and the dichloromethane one from N. acutifolia both showed 100% inhibition in this bioassay. Additionally, from the phytochemical screening on the dichloromethane and methanol extracts it was found that compounds such as alkaloids, phenols and terpenes were present in most of the extracts evaluated and they might be the cause of the antifungal activities reported.     

Ethylene and the Regulation of Apple Stem Growth under Stress

Bending stree resulted in an increase in the ethylene concentration in the internal atmosphere of apple stem (Malus domestica Borkh. cv. Winesap). reaching a maximum at about 2 days after bending. The rise in ethylene content was followed by a depression of growth at about 14–21 days. Ethylene content returned to control levels after about 3 weeks. Application of a past naphthaleneacetic acit caused a similar increase in ethylene levels, and the application of ethephon pastes brought about an inhibition of elongation growth. Whereas stress treatment resulted in an inhibition of growth in stem diameter as well as elongation of growth in stem diameter as well as elongation, the ethephon applications resulted in a stimulation of growth in diameter. It is suggested that ethylene may be involved in the growth responses to mechanical stress.     

醉马草水浸液对豌豆蚜触杀活性及种群增长的影响

为探讨醉马草水浸液对豌豆蚜触杀活性及种群增长的影响,采用带虫浸叶法比较不同生育期醉马草带菌（E+）和不带菌（E-）水浸液对豌豆蚜触杀活性及种群生命表,测定了豌豆蚜的死亡率及触杀后对其生殖期,平均繁殖力,繁殖率及生命表参数的影响。结果表明,不同生育期醉马草带菌（E+）水浸液触杀豌豆蚜后对其各项指标均有显著影响。在苗期时,E+水浸液触杀豌豆蚜后校正死亡率最高,繁殖力最低,内禀增长率（r_m=0.145 d^-1）和净生殖率（R₀=4.802头）均为最小值。在成熟期时,E+水浸液触杀豌豆蚜24 h、48 h和72 h后校正死亡率分别为26.15%,19.01%,9.07%;繁殖期（3.87 d）,平均繁殖力（8.80头）,繁殖率（1.40%）,内禀增长率（r_m=0.208 d^-1）和净生殖率（R₀=8.820头）。在枯黄期时,E+水浸液触杀豌豆蚜后校正死亡率最低,繁殖力最强,内禀增长率（r_m=0.247 d^-1）和净生殖率（R₀=13.647头）均为最大值。不同生育期醉马草E-水浸液触杀豌豆蚜后对其种群繁殖无显著影响,与对照差异不显著（P>0.05）。综上,苗期醉马草E+水浸液对豌豆蚜有较好的触杀效果,校正死亡率高,且触杀后当代繁殖力减弱,种群扩建时间延长,不利于其种群繁殖和增长;故苗期醉马草E+水浸液具有很好的杀虫潜力,所采用水浸液方法制备简单,成本低,可为新型植物源农药研发提供重要理论依据。     

The participation of the cell wall hydrolytic enzymes in the initial colonization of Azospirillum brasilense on wheat roots

The effect of cellulase and pectinase on bacterial colonization of wheat was studied by three different experiments. In the first experiment, the root colonization of 3 wheat cultivars (Ghods, Roshan and Omid) by two A. brasilense strains (Sp7 and Dol) was compared using pre-treated roots with cellulase and pectinase, and non-treated with these enzymes (control). Although the root colonization varied greatly among strain-plant combinations in controls, the pre-treatment of roots with polysaccharide degrading enzymes significantly increased the bacterial count in roots, regardless of the strain-plant combination. This might be an indication that cell wall may act as an important factor in plant-Azospirillum interaction. In the second experiment, the root cellulase activity of the same wheat cultivars treated with and without the two Azospirillum brasilense, strains (Sp7 and Dol) was compared. The pre-treatment of wheat roots with Azospirillum enhanced the cellulase activity of wheat root extracts. Thus, the cellulase activity might participate in the initial colonization of wheat roots by Azospirillum. The comparison of the cellulase activity of root extracts within inoculated and non-inoculated seedlings showed that the inoculation had enhanced the cellulase activity in root extracts, but this effect was directly dependent on the strain-plant combination. Strain Sp7 stimulated the highest cellulase activity in cv. Roshan, but strain Dol induced the highest enzyme activity in cv. Ghods. In the third experiment, several growth parameters of those 3 wheat cultivars treated with and without those two bacterial strains (Sp7 and Dol) were compared. The highest magnitude of growth responses caused by Sp7 strain was in the cv Roshan, but Dol strain stimulated the highest growth in cv Ghods. Therefore, effective colonization may contribute to more growth responses.     

Purification of glutaryl-CoA dehydrogenase from Pseudomonas sp., an enzyme involved in the anaerobic degradation of benzoate

Cell-free extracts of Pseudomonas sp. strains KB 740 and K 172 both contained high levels of glutaryl-CoA dehydrogenase when grown anaerobically on benzoate or other aromatic compounds and with nitrate as electron acceptor. These aromatic compounds have in common benzoyl-CoA as the central aromatic intermediate of anerobic metabolism. The enzymatic activity was almost absent in cells grown aerobically on benzoate regardless whether nitrate was present. Glutaryl-CoA dehydrogenase activity was also detected in cell-free extracts of Rhodopseudomonas, Rhodomicrobium and Rhodocyclus after phototrophic growth on benzoate. Parallel to the induction of glutaryl-CoA dehydrogenase as measured with ferricenium ion as electron acceptor, an about equally high glutaconyl-CoA decarboxylase activity was detected in cell-free extracts. The latter activity was measured with the NAD-dependent assay, as described for the biotin-containing sodium ion pump glutaconyl-CoA decarboxylase from glutamate fermenting bacteria. Glutaryl-CoA dehydrogenase was purified to homogeneity from both Pseudomonas strains. The enzymes catalyse the decarboxylation of glutaconyl-CoA at about the same rate as the oxidative decarboxylation of glutaryl-CoA. The green enzymes are homotetramers (m=170 kDa) and contain 1 mol FAD per subunit. No inhibition was observed with avidin indicating the absence of biotin. The N-terminal sequences of the enzymes from both strains are similar (65%).     

Changes in fatty acids composition,hydrogen peroxide generation and lipid peroxidation of salt-stressed corn (<Emphasis Type="Italic">Zea mays</Emphasis> L.) roots

Comparative study about the salt-induced oxidative stress and lipid composition has been realised in primary root tissues for two varieties of maize (Zea mays L.) in order to evaluate their responses to salt stress. The root growth, root water content (WC), hydrogen peroxide (H₂O₂) generation, lipid peroxidation, membrane stability index and the changes in the profile of fatty acids composition were investigated. Salinity impacts in term of root growth, water content, H₂O₂ generation, lipid peroxidation and membrane destabilisation were more pronounced in primary roots of Aristo than in those of Arper indicating more sensitivity of the first variety. It was confirmed by gas chromatography that the composition of fatty acids in roots of both varieties was constituted mainly by 16:0 and 18:0 as major saturated fatty acids and 18:1ω9, 18:2ω6 and 18:3ω3 as major unsaturated fatty acids. Total lipid extracts from the roots of both varieties showed that the lipid saturation level increased under salt stress, notwithstanding the increased proportion of polyunsaturated fatty acids. The changes in lipid saturation being predominantly due to decreases in oleic acid (18:1ω9) and increases in palmitic acid (16:0). However, Arper root extracts contained a lower proportion of saturated lipids than Aristo. The enhanced proportion of highly polyunsaturated fatty acids especially linolenic and eicosapentaenoic acids was considered to be the characteristic of the relatively salt tolerance in Arper roots.     

Tea extracts differentially inhibit Streptococcus mutans and Streptococcus sobrinus biofilm colonization depending on the steeping temperature

Abstract

This study aimed to evaluate the effects of tea extracts on oral biofilm colonization depending on steeping temperature. S. mutans and S. sobrinus were cultured and treated with green or black tea extracts prepared under different steeping conditions. Biofilm formation, glucosyltransferase (GTF) levels, bacterial growth, and acidogenicity were evaluated. Biofilms were also assessed by gas chromatography-mass spectrometry and confocal laser scanning microscopy. All extracts with hot steeping showed higher inhibitory effects on biofilm formation and cell viability and lower GTF levels compared with those with cold steeping (p?<?0.05). Hot steeping significantly reduced bacterial growth (p?<?0.05) and maintained the pH. Catechins were only identified from hot steeping extracts. Within the limits of this study, extracts with cold steeping showed lower inhibitory effects on oral biofilms. The different effects between steeping extracts may be attributed to the difference in catechins released from tea extracts under the different steep conditions.     

Isolation of a factor stimulatory to Bradyrhizobium japonicum in broth culture

Previous experiments indicated that water extracts of lambsquarters (Chenopodium album) and green foxtail (Setaria viridis), among others, stimulated growth of Bradyrhizobium japonicum in broth culture. Water extracts of lambsquarters shoots collected before or after anthesis were equally stimulatory. The stimulatory effect of extracts of lambsquarters when heated to 100°C for 30 min or autoclaved for 15 min was reduced by about 20% compared to untreated extracts. Extracts of green foxtail were less affected by higher temperature under similar conditions. Extracts of both green foxtail and lambsquarters completely lost their stimulatory effect following exposure to aerial microflora for 120 h. Water extract of lambsquarters shoots was more stimulatory than methanol extract, and neither ether nor butanol extracts resulted in stimulation. Both shoots and roots of lambsquarters and green foxtail were sequentially extracted first by water followed by methanol and vice-versa. The bioassay of these extracts indicated that there could be two components of the growth factor-one, larger component is soluble in water, the other, smaller component is soluble in methanol. After fractionation of the crude aqueous extract of lambsquarters shoots by four organic solvents, the residual aqueous extract retained the growth factor. Dialysis of the residual aqueous extract of lambsquarters shoots through a membrane (MWCO 1000) indicated that the molecular weight of the growth factor was less than 1000. The fraction having molecular weight <1000 was separated by paper chromatography using 6% acetic acid as developer. The fraction with Rf 0.91 showed the highest stimulation of the bacterium.