Application of the chloroform fumigation-incubation method to the estimation of soil microbial biomass in burned and unburned Japanese red pine forests

Abstract Estimation of soil microbial biomass in burned and unburned Japanese red pine forests was attempted using the chloroform fumigation-incubation method. As the amount of CO₂-C evolved from the fumigated soil for 10–20 days after fumigation (designated as F') was always lower than that from the unfumigated soil during the same period (UF'), the formula, microbial biomass-C(M) = the amount of CO₂-C evolved from the fumigated soil for 0–10 days after fumigation, F) − F'/ k _c, was proposed instead of Jenkinson's conventional formula, M = (F − UF')/ k _c. The k _c value was also determined as 0.30 using 3 fungal and 3 bacterial cultured species as internal standards. Microbial biomass-C calculated by (F − F')/0.30 decreased with soil depth at both the burned (Nenoura, 3.5 years after fire) and unburned (Ato) sites, showing the significant correlation with the decrease of soil respiration and organic C content along soil depth. Microbial biomass-C in the 0–2 cm soil layer at the burned site at Nenoura was 130 mg/100 g dry soil and those in the HF horizon and 0–2 cm soil layer at the unburned site at Ato were 686 and 146 mg/100 g dry soil, respectively.     

Determination ofin situ KN by the chloroform fumigation-incubation method and mineralization of biomass N under anaerobic conditions

A silt loam soil from Pakistan was incubated at 30°C with increasing levels (67, 133, 200, 267 and 333 μg N g^?1 soil) of¹⁵N-labelled (NH₄)₂SO₄ and glucose (C/N ratio of 30 for all additions). At a stage when all of the applied¹⁵N was immobilized (transformed into microbial biomass), moist soil samples were subjected to the chloroform fumigation-incubation method (CFIM) for determination of K_N and microbial biomass. Mineralization of biomass derived from the applied¹⁵N and the native soil N was studied under anaerobic conditions. In situ values of K_N varied from 0.19 to 0.42 and increased with increasing levels of amendment (N + glucose). From 10 to 18% of the native soil N was found as microbial biomass. Anaerobic incubation of the soils resulted in the mineralization (determined as NH ₄ ⁺ ) of 15.08 to 29.23% of the biomass¹⁵N at different levels of amendment; 2.90 to 4.43% of the native soil N was mineralized. From 70 to 90% of the N mineralized from native soil N was derived from microbial biomass; the rest was attributed to non-biomass N.     

Monitoring of changes in physical and microbiological properties of a Chernozem amended with different organic substrates

A soil microcosm study was made to monitor changes in soil physical and microbiological properties of a Chernozem during a period of up to 126 or 252 days following the addition of whey, straw or vegetable oil. In the whey treatment soil maximum water-holding capacity (MWHC) had decreased after seven and 28 days of incubation. At both dates, the differences to the untreated control were significant. Straw was able to increase MWHC of soil during incubation and after 42 and 126 days values differed significantly from those of the control. Compared with the control, whey, oil and straw treatments had higher meanweight diameter of dry aggregates. The differences were significant after seven, 28 and 126 days with whey, after 42, 126 and 252 days with oil, and after 126 days with straw. The sensitivity of dry aggregates to abrasion (SAA), representing a negative index of dry aggregate stability, was lower in the whey treatment than in the control after three and seven days incubation. In the later phase of incubation, whey tended to increase SAA. A trend to increase SAA also was observed with straw and after 126 days a significantly higher SAA for the straw than for the oil treatment was determined. This trend still was to observe after 252 days incubation. An increase in SAA observed for the oil treatment after 42 days was followed by a decrease till the end of incubation. Aggregates of organic treatments were more resistant to the dispersive effect of water than those of the control. Microbial biomass-C contents were high in the whey treatment, ranging between 1931 and 754 g g^–1 soil dry mass during incubation. With whey, fungal contributions to biomass-C increased from 40.5% after three to 76.5% after 126 days incubation. Addition of straw or oil stimulated biomass synthesis less than whey. High fungal contributions to biomass-C, approx. 70%, were sustained by straw during incubation. With oil, fungal contributions were 20.5% after three, 76% after 42 and less than 20% after 126 and 252 days incubation. Fungal contributions to biomass-C correlated positively with SAA. High sensitivity of the fungal biomass to mechanical stress is discussed as a cause for the low dry aggregate stability of soils amended with organic substrates encouraging fungal biomass development.     

Effects of Zn and P addition on the microbial biomass in a Zn deficient calcareous soil amended with glucose

A 35-day laboratory incubation experiment at 25°C was carried out to investigate the effects of Zn and P addition on microbial biomass C, N, and P in a Zn deficient calcareous soil, sampled at 15–40 cm depth in Central Anatolia, Turkey, amended with glucose. The underlying hypothesis was that P, but also Zn addition leads to a decrease in the microbial biomass C/N ratio. In the glucose-amended soil, the microbial biomass C/N ratio was not affected by the addition of P at day 5. At day 35 in this treatment, the significant P addition × day interaction revealed a significant decrease in the microbial biomass C/N ratio from 11.3 to 8.9. In the glucose-amended soil, Zn addition also had generally significant negative effects on microbial biomass C in comparison with the pure glucose treatment. A similar tendency was observed for microbial biomass N and consequently the microbial biomass C/N ratio remained unaffected. No evidence was found in the present incubation experiment that the microbial community suffered from Zn deficiency.     

Temporal changes in soil microbial biomass carbon in an arable soil. Consequences for soil sampling

Sugar beet, winter wheat and winter barley were planted within a crop rotation on an arable soil with conventional soil management. Soil samples were taken monthly from different depths of the whole plough layer (0–10, 10–20 and 20–30 cm) during a 56 month period. The samples were analysed for microbial biomass carbon using the substrate-induced respiration technique. Temporal changes in the amount of microbial biomass carbon were observed. Within a year, microbial biomass-C varied from low values (−15% of total mean) in winter to high values (+15% of total mean) in summer. Relative deviations from the annual means were calculated for each month in the year to demonstrate these fluctuations. Temporal changes in microbial biomass-C depended on the sources of sample variation (5 years, 3 crops, 3 sampling depths). The highest relative deviation from the annual mean microbial biomass-C was attributable to the factor “year”. Less variations were caused by “crops” and “sampling depth”. Soil microbial biomass-C remained constant during frost periods. From the observed temporal changes, recommendations for a suitable date for soil sampling are given, which allows a representative estimation of the mean annual microbial biomass-C content in arable soils.     

Chronic and acute effects of thyrotropin on phosphatidylinositol turnover in cultured porcine thyroid cells

The 32P incorporation into phospholipids of isolated porcine thyroid cells, cultured for 1-4 days, has been studied in subsequent 2-h incubations. Along with culture ageing, decreased 32P incorporation into total phospholipid of control cells was observed. The presence of 40 munits/ml TSH during the 2 h incubation yielded a relative increase in labelling of phosphatidylinositol, named 'acute phospholipid effect'. A chronic treatment of the cells with TSH concentration ranging from 0.1 to 10 munits/ml ensured the maintenance of a high turnover rate of total phospholipids. The analysis of individual phospholipids revealed that 1-day culture cells in the presence of 0.1 munits/ml TSH presented a strong increase of phosphatidylinositol labelling. This 'chronic phospholipid effect' of TSH can be reproduced by a chronic treatment with dibutyryl cyclic AMP (10(-3)M) or prostaglandin E2 (10(-6)M), which did not evoke a classical phospholipid effect in a 2 h incubation. If TSH (40 munits/ml) is added to the cells in a 2 h incubation, control cells show the classical phospholipid effect whereas cells chronically treated with TSH, dibutyryl cyclic AMP or prostaglandin E2 presented a 'reverse phospholipid effect' i.e. a relative decrease in phosphatidylinositol labelling. 10(-4)M cycloheximide presence during the last 12 h of culture prevented the establishment of the 'chronic phospholipid effect' and of its consequence, 'the reverse phospholipid effect'. On the basis of these results a scheme is proposed in keeping with current hypotheses concerning phosphatidylinositol metabolism.     

Composition and synthesis of cellular lipids in Neurospora crassa during cellular differentiation.

The synthesis of cellular lipids of Neurospora crassa was measured during growth on low (2% sucrose)- and high (15% glucose)-carbohydrate supplementation. The amount of lipid per dry weight of cells does not change during the germination and early logarithmic growth periods, but the percentage of phospholipid in the lipid does increase, reaching a maximal value of 90% at 4 to 5 h after inoculation, at which time the phospholipid content of the cells is approximately 60 mumol/g (dry weight). The content of the anionic phospholipids, as a percentage of the lipid fraction, is relatively constant during the growth period, but the contents of the zwitterionic phospholipids phosphatidylcholine and phosphatidylethanolamine change in a reciprocal fashion. During the first 8 h of growth, phosphatidylcholine falls from 53% of the phospholipid to 43%, whereas phosphatidylethanolamine rises from 29 to 38%. The total of these two phospholipids is approximately 83% during the growth period studied. The synthesis of cellular phospholipids, measured either by [32P]H3PO4 or [14C]glucose incorporation, reached maximal levels between 3 and 5 h of growth. The effect of the high-carbohydrate supplement on cellular lipids was minimal. Inclusion of 15% glucose decreased the labeling of phospholipid by [32P]H3PO4, but did not affect lipid composition. This observation is in contrast to the effects of high glucose on mitochondrial phospholipid synthesis.     

Microbial Communities of Continuously Cropped, Irrigated Rice Fields

In continuously cropped, irrigated rice fields, soil microbial biomass as measured by total phospholipid fatty acid concentrations declined during the second half of the crop cycle. This decline was also observed in other components of the microbial community assessed by viable counts, including denitrifiers and sporeformers. Simultaneous with total biomass decline was the increase in potential indicators of nutrient stress--such as ratios of cyclopropanol ((Sigma)[cy/(omega)7c]) and trans ((Sigma)[(omega)7t/(omega)7c]) phospholipid fatty acids--in plain crop soil but not in the rhizosphere. Polyhydroxyalkanoate levels were enhanced in the root environment of mature rice. Polyunsaturated eukaryotic biomarkers accounted for only 13 to 16 mol% of the total phospholipids, including 2 mol% of 18:2(omega)6, which is considered a fungal biomarker. Single biomarkers for defined physiological groups of bacteria did not follow the declining trend of total microbial biomass. Signature compounds for gram-positive and gram-negative fermenters (plasmalogen phospholipids), methanogenic bacteria (diether lipids), and methanotrophs (18:1(omega)8c) increased as the crop approached maturity. Methanotrophs were not particularly enriched in the rhizosphere. Methanogenic biomarkers were, however, most abundant in root extracts from mature rice plants. Assuming that soil microbial biomass plays a significant role as a passive nutrient pool, its reduction during the second half of the cropping season suggests a mechanism that may ultimately contribute to declining productivity in irrigated, continuous rice cropping systems.     

重金属Cd、Zn、Cu、Pb对土壤微生物和酶活性的影响

采用室内培养实验(25℃),研究了不同培养时间下重金属Cd、Zn、Cu、Pb(浓度分别为50,800,400,800mg.kg-1)污染对土壤微生物和酶活性的影响。结果表明,土壤蔗糖酶、过氧化氢酶和脱氢酶活性随着培养时间的增加而显著下降,在培养20d的时候达到最小值,然后酶活性缓慢升高。Cu对脲酶活性以及Cd对酸性磷酸酶和脲酶活性的抑制作用随时间增加而增加。土壤微生物生物量碳、细菌、真菌和放线菌数量随培养时间的增加均表现出先降低后升高的变化趋势。Cd和Cu对微生物生物量氮的抑制作用则随着培养时间的增加而增强,在培养30d时微生物生物量氮到达最低值,分别较培养10天减少了12.6%和16.5%。     

水分对武夷山草甸土壤有机碳激发效应的影响

水分是影响土壤有机碳激发效应的重要因子,但水分如何影响山地草甸土有机碳激发效应尚不清楚.本试验以武夷山高海拔(2130 m)山地草甸土为研究对象,通过室内添加13C标记的葡萄糖结合控制土壤水分(30％FWC和60％ FWC,FWC为田间持水量),进行为期126 d的室内培养试验,定期测定CO2浓度和13C-CO2丰度值...     

Changa in the structure and activity of a soil microbial community caused by inorganic nitrogen fertilization

The changes in the structure and activity of a soil microbial community caused by addition of moderate and high rates of the mineral nitrogen fertilizer (KNO₃) were studied in a laboratory incubation experiment. The structure of the microbial community was evaluated from the phospholipid fatty acid (PLFA) profile; specific growth rate of the microorganisms was determined by the method of the kinetics of substrate-induced respiration; the total pool of microbial carbon was estimated by the fumigation-extraction method. The amounts of nitrogen fertilizer applied in three treatments of the experiment were 0 (control), 100, and 2000 ??g N/g soil. Even in the absence of additional sources of organic carbon, a considerable portion of the added ¹⁵N (up to 74%) was immobilized. No significant increase in the amount of microbial carbon was observed during incubation. The specific growth rate of the microbial community in soil supplemented with glucose decreased twofold after addition of 2000 ??g N/g soil. In this treatment, the ratio of cyclic fatty acids to their monoenoic precursors also increased, indicating the adaptation of microbial cells to extremely high amounts of nitrogen fertilizer. Moreover, considerable changes in the structure of the soil microbial community, such as an increase in the ratio of fungalto bacterial markers and a decrease in the ratio between PLFA of gram-positive and gram-negative bacteria, were observed in the treatment with addition of 2000 ??g N/g soil. Our data clearly indicate that mineral nitrogen fertilization of soil under carbon limitation has a pronounced impact on the structure and activity of soil microbial communities.     

The interaction of insulin with phospholipids

1. A simple two-phase chloroform–aqueous buffer system was used to investigate the interaction of insulin with phospholipids and other amphipathic substances. 2. The distribution of ¹²⁵I-labelled insulin in this system was determined after incubation at 37°C. Phosphatidic acid, dicetylphosphoric acid and, to a lesser extent, phosphatidylcholine and cetyltrimethylammonium bromide solubilized ¹²⁵I-labelled insulin in the chloroform phase, indicating the formation of chloroform-soluble insulin–phospholipid or insulin–amphipath complexes. Phosphatidylethanolamine, sphingomyelin, cholesterol, stearylamine and Triton X-100 were without effect. 3. Formation of insulin–phospholipid complex was confirmed by paper chromatography. 4. The two-phase system was adapted to act as a simple functional system with which to investigate possible effects of insulin on the structural and functional properties of phospholipid micelles in chloroform, by using the distribution of [¹⁴C]glucose between the two phases as a monitor of phospholipid–insulin interactions. The ability of phospholipids to solubilize [¹⁴C]glucose in chloroform increased in the order phosphatidylcholine<sphingomyelin<phosphatidylethanolamine<phosphatidic acid. Insulin decreased the [¹⁴C]glucose solubilized by phosphatidylcholine, phosphatidylethanolamine and phosphatidic acid, but not by sphingomyelin. 5. The significance of these results and the molecular requirements for the formation of insulin–phospholipid complexes in chloroform are discussed.     

Dynamics of a microbial community associated with manure hot spots as revealed by phospholipid fatty acid analyses.

Microbial community dynamics associated with manure hot spots were studied by using a model system consisting of a gel-stabilized mixture of soil and manure, placed between layers of soil, during a 3-week incubation period. The microbial biomass, measured as the total amount of phospholipid fatty acids (PLFA), had doubled within a 2-mm distance from the soil-manure interface after 3 days. Principal-component analyses demonstrated that this increase was accompanied by reproducible changes in the composition of PLFA, indicating changes in the microbial community structure. The effect of the manure was strongest in the 2-mm-thick soil layer closest to the interface, in which the PLFA composition was statistically significantly different (P < 0.05) from that of the unaffected soil layers throughout the incubation period. An effect was also observed in the soil layer 2 to 4 mm from the interface. The changes in microbial biomass and community structure were mainly attributed to the diffusion of dissolved organic carbon from the manure. During the initial period of microbial growth, PLFA, which were already more abundant in the manure than in the soil, increased in the manure core and in the 2-mm soil layer closest to the interface. After day 3, the PLFA composition of these layers gradually became more similar to that of the soil. The dynamics of individual PLFA suggested that both taxonomic and physiological changes occurred during growth. Examples of the latter were decreases in the ratios of 16:1 omega 7t to 16:1 omega 7c and of cyclopropyl fatty acids to their respective precursors, indicating a more active bacterial community. An inverse relationship between bacterial PLFA and the eucaryotic 20:4 PLFA (arachidonic acid) suggested that grazing was important.     

Mineralization of C and N from microbial biomass in paddy soil

Summary Soil samples of paddy fields with different fertilizer managements in Yamaguchi Agricultural Experiment Station, Japan were used to investigate the contribution of microbial biomass to the pool of mobile plant nutrients in paddy soil. The quantities of nutrients mobilized in soils which had been fumigated or dried were closely related to the quantities available in freshly killed biomass. A K_N-factor (28 days) of 0.24 for the proportion of total N mineralized from dead biomass in paddy soils was obtained. It was observed that the C to N ratio mineralized from freshly killed biomass by chloroform fumigation of paddy soils was nearly 10 under aerobic conditions. For an approximate calculation of biomass C from the flush-N by chloroform fumigation of paddy soils, the equations of (B=33 Fn, 10 days) and (B=26 Fn, 28 days) were indicated. In oven-dried (70°C, 24 h) and rewetted soils, about 66% of N was mineralized from the freshly killed biomass during 28 days of incubation and the remaining 34% was derived from non-biomass organic matter of paddy soils.     

内生真菌感染对禾草宿主生境土壤特性和微生物群落的影响

以羊草(Leymus chinensis)-内生真菌共生体为研究对象, 分别在野外样地和室内盆栽两种实验条件下研究了内生真菌感染对土壤特性和微生物群落结构的影响。结果显示：在处理时间较长并伴随有枯落物分解的羊草样地中, 内生真菌感染促进了土壤氮(N)的积累, 提高了30天培养时间内土壤初始碳(C)矿化速率和前3天土壤矿化量和土壤矿化总量; 而在处理时间较短且没有地上枯落物分解的盆栽羊草中, 内生真菌感染对土壤的C、N含量及C矿化均无显著影响。无论是野外样地还是室内盆栽实验, 内生真菌感染均未引起土壤微生物磷脂脂肪酸种类的变化, 但内生真菌感染均有提高土壤微生物生物量的趋势, 内生真菌显著增加了盆栽羊草土壤中细菌、革兰氏阴性细菌、真菌磷脂脂肪酸含量和磷脂脂肪酸总量, 增加了羊草样地土壤中革兰氏阳性细菌和放线菌的磷脂脂肪酸含量。总体看来, 内生真菌感染能够改变土壤N积累和C矿化率, 并且改变土壤中微生物群落的结构, 这有助于进一步认识内生真菌与羊草之间的共生关系及其在生态系统C、N循环中所起的作用。     

Metabolism of the Glucosyl Diglycerides and Phosphatidylglucose of Staphylococcus aureus

A glucose containing lipid, phosphatidylglucose (probably 3-sn-phosphatidyl-1'-glucose) and a lipid tentatively identified as phosphatidylethanolamine have been characterized in the lipids of Staphylococcus aureus. These lipids together comprise less than 2% of the total phospholipids of exponentially growing S. aureus and accumulate to 14% of the total phospholipid in stationary-phase cells. These lipids lost no (32)P when cells grown with H(3) (32)PO(4) were transferred to nonradioactive medium during the exponential growth phase. This was in marked contrast to the other phospholipids which lost (32)P rapidly. The loss of (32)P from phosphatidic acid and cardiolipin in exponentially growing cells was biphasic, suggesting heterogeneity of phospholipid phosphate metabolism. The mono- and diglucosyl diglycerides showed a rapid loss of (14)C-glucose during growth in nonradioactive medium but no loss of (14)C from the fatty acids of these lipids. The (14)C in the glucose and fatty acids of the glucosyl diglycerides was derived from glucose.     

Metabolite Changes in the Cerebral Cortex of Treated and Untreated Infant Hydrocephalic Rats Studied Using In Vitro 31P-NMR Spectroscopy

Abstract: The effect of hydrocephalus on cerebral energy metabolites and on intermediates of membrane phospholipid metabolism has been studied in H-Tx rats with inherited infantile hydrocephalus. Hydrocephalic rats and rats with shunts placed at 4–5 days or at 10 days after birth were subjected to magnetic resonance imaging in vivo before 21 days of age to determine the dimensions of the ventricles and cortex. At 21 days, the brains from the three groups of rats, together with age-matched control littermates, were frozen in situ, and chloroform/methanol extracts of cerebral cortex were prepared for high-resolution ³¹P-NMR spectroscopy. Hydrocephalus resulted in modest decreases in most metabolites quantified. Levels of phosphocreatine, ATP, and diphosphodiesters plus NAD were significantly reduced by 23–32%, and inorganic phosphate content was reduced but not significantly. Levels of the membrane phospholipid intermediates phosphorylethanolamine, glycerophosphorylethanolamine, and glycerophosphorylcholine were also significantly reduced by 30–33%, indicating changes in membrane metabolism. These general decreases are consistent with a loss of cell contents, possibly due to changes in dendrite structure in hydrocephalus. Rats shunt-treated at 4–5 days were similar to control rats for all energy metabolites, but those treated later at 10 days had reduced phosphocreatine and ATP levels. Shunt-treated rats also had reductions in levels of membrane phospholipids, some of which occurred in sham-operated rats. It is concluded that hydrocephalus leads to reductions in levels of energy metabolites and in levels of membrane phospholipids and that the changes in energy metabolites can be reversed by early, but not by later, shunt treatment.     

Estimating high-affinity methanotrophic bacterial biomass, growth, and turnover in soil by phospholipid fatty acid 13C labeling

A time series phospholipid fatty acid (PLFA) 13C-labeling study was undertaken to determine methanotrophic taxon, calculate methanotrophic biomass, and assess carbon recycling in an upland brown earth soil from Bronydd Mawr (Wales, United Kingdom). Laboratory incubations of soils were performed at ambient CH4 concentrations using synthetic air containing 2 parts per million of volume of 13CH4. Flowthrough chambers maintained a stable CH4 concentration throughout the 11-week incubation. Soils were analyzed at weekly intervals by gas chromatography (GC), GC-mass spectrometry, and GC-combustion-isotope ratio mass spectrometry to identify and quantify individual PLFAs and trace the incorporation of 13C label into the microbial biomass. Incorporation of the 13C label was seen throughout the experiment, with the rate of incorporation decreasing after 9 weeks. The delta13C values of individual PLFAs showed that 13C label was incorporated into different components to various extents and at various rates, reflecting the diversity of PLFA sources. Quantitative assessments of 13C-labeled PLFAs showed that the methanotrophic population was of constant structure throughout the experiment. The dominant 13C-labeled PLFA was 18:1omega7c, with 16:1omega5 present at lower abundance, suggesting the presence of novel type II methanotrophs. The biomass of methane-oxidizing bacteria at optimum labeling was estimated to be about 7.2 x 10(6) cells g(-1) of soil (dry weight). While recycling of 13C label from the methanotrophic biomass must occur, it is a slower process than initial 13CH4 incorporation, with only about 5 to 10% of 13C-labeled PLFAs reflecting this process. Thus, 13C-labeled PLFA distributions determined at any time point during 13CH4 incubation can be used for chemotaxonomic assessments, although extended incubations are required to achieve optimum 13C labeling for methanotrophic biomass determinations.     

短期增温和增加降水对内蒙古荒漠草原土壤呼吸的影响

利用红外辐射增温装置模拟短期持续增温和降水增加交互作用对内蒙古荒漠草原土壤呼吸作用的影响, 结果表明: 土壤含水量对月土壤呼吸的影响显著大于土壤温度增加的影响, 生长旺季的月土壤呼吸显著大于生长末季; 土壤温度和水分增加都显著影响日土壤呼吸, 但二者的交互作用对土壤呼吸无显著影响。荒漠草原7‒8月平均土壤呼吸速率为1.35 μmol CO₂·m ^-2·s ^-1, 7月份为2.08 μmol CO₂·m ^-2·s ^-1, 8月份为0.63 μmol CO₂·m ^-2·s ^-1。土壤呼吸与地下各层根系生物量呈幂函数关系, 0‒10 cm土层的根系生物量对土壤呼吸的解释率(79.2%)明显高于10‒20 cm土层的解释率(31.6%)。0-10 cm土层的根系生物量是根系生物量的主体, 根系生物量对土壤呼吸的影响具有层次性。在未来全球变暖和降水格局变化的情景下, 荒漠草原土壤水分含量是影响生物量的主导环境因子, 而根系生物量的差异是造成土壤呼吸异质性的主要生物因素, 土壤含水量可通过影响根系生物量控制土壤呼吸的异质性。     

Photo-induced inactivation and uncoupling of gonadotropin receptors in rat ovarian plasma membrane

Extraction of membranes of Lactobacillus plantarum with Triton X-100/glycerol solubilized up to 80% of the undecaprenol kinase activity. Fractionation of the extract by gel chromatography separated endogenous phospholipid from the enzyme but simultaneously inactivated the enzyme. The kinase was reactivated by reconstitution with various synthetic phosphatidylcholines and purified L. plantarum phospholipids. Ditetradecanoylphosphatidylcholine and lysylphosphatidylglycerol were the best activators. Furthermore, the optimal environment for enzyme stimulation was provided by different defined molar ratios of Triton X-100/phospholipid. The ratios for the phospholipids tested ranged from 1.25 to 6.3. Similar substrate specificity and kinetic constants were observed for both the solubilized and reconstituted enzymes suggesting that no fundamental changes in the enzyme activity occurred during the delipidation-reconstitution process.