Surface Percolation for Soil Improvement by Biocementation Utilizing In Situ Enriched Indigenous Aerobic and Anaerobic Ureolytic Soil Microorganisms

The use of biocementation via microbially induced carbonate precipitation (MICP) for improving the mechanical properties of weak soils in the laboratory has gained increased attention in recent years. This study proposes an approach for applying biocementation in situ, by combining the surface percolation of nutrients and cementation solution (urea/CaCl₂) with in situ cultivation of indigenous soil urease positive microorganisms under non-sterile conditions. The enrichment of indigenous ureolytic soil bacteria was firstly tested in batch reactors. Using selective conditions (i.e., pH of 10 and urea concentrations of 0.17 M), highly active ureolytic microorganisms were enriched from four diverse soil samples under both oxygen-limited (anoxic) and oxygen-free (strictly anaerobic) conditions, providing final urease activities of more than 10 and 5 U/mL, respectively. The enrichment of indigenous ureolytic soil microorganisms was secondly tested in pure silica sand columns (300 and 1000 mm) for biocementation applications using the surface percolation approach. By applying the same selective conditions, the indigenous ureolytic soil microorganisms with high urease activity were also successfully enriched for both the fine and coarse sand columns. However, the in situ enriched urease activity was highly related to the dissolved oxygen of the percolated growth medium. The results showed that the in situ cultivated urease activity may produce non-clogging cementation over the entire 1000-mm columns, with unconfined compressive strength varying between 850–1560 kPa (for coarse sand) and 150–700 kPa (for fine sand), after 10 subsequent applications of cementation solution. The typically observed loss of ureolytic activity during the repeated application of the cementation solution was recovered by providing more growth medium under selective enrichment conditions, enabling the in situ enriched ureolytic microorganisms to increase in numbers and urease activity in such a way that continued cementation was possible.     

Environmental Factors Affecting the Compressive Strength of Microbiologically Induced Calcite Precipitation-Treated Soil

Some microorganisms such as Sporoscarcina pasteurii precipitate calcium carbonate and are suitable for biocementation. This study aimed to investigate the effects of several factors including concentration of bacteria, chemical reactants, temperature, and pH on precipitation of calcium carbonate. The results showed that after 7 and 14 days of curing, the compressive strength of silty clay soil samples increased steadily as pH increased from 5 to 9. It was observed that pH plays an important role in biocementation. The highest compressive strength (i.e. 92 kPa) was observed when the soil was treated with 50 ml of bacterial solution after 14 days of curing. In addition, it was observed that the highest compressive strength of samples was achieved when the temperature was 40°C.     

Inhibitory activity against the fish pathogen Lactococcus garvieae produced by Lactococcus lactis TW34, a lactic acid bacterium isolated from the intestinal tract of a Patagonian fish

After enrichment of Odontesthes platensis intestinal contents, 53 lactic acid bacteria (LAB) were isolated. From the four isolates that showed inhibitory activity against Lactococcus garvieae 03/8460, strain TW34 was selected because it exerted the strongest inhibition. It also inhibited other Gram-positive bacteria, but not Gram-negative fish pathogens. Phenotypic and 16S rDNA phylogenetic analyses showed that TW34 belongs to Lactococcus lactis. In addition, TW34 showed to be sensitive to different antibiotics. The production of the inhibitory agent against L. garvieae was growth associated, and it was significantly influenced by the incubation temperature. The optimal temperature for the antimicrobial production was as low as 15°C. Both acidification and hydrogen peroxide production were ruled out as the source of inhibition. In contrast, the antimicrobial activity was completely lost by treatment with proteolytic enzymes, which confirmed that the inhibitory substance was a bacteriocin. The bacteriocin was highly thermostable (121°C for 15 min) and active between pH 3 and 11. It remained stable for up to 2 months when stored at 4°C and up to 6 months at −20°C. Our results suggest that the strain L. lactis TW34 could provide an alternative for lactococcosis control and therefore be considered for future challenge experiments with fish.     

Isolation and identification of bacterial strains with insecticidal activities from Rhynchophorus ferrugineus Oliver (Coleoptera: Curculionidae)

Several pathogenic bacteria strains were isolated from dead larvae of the weevil, Rhynchophorus ferrugineus Oliver, collected on palm trees in Taiwan, China. Strains of pure cultures were temporarily named TW‐1, TW‐2, TW‐3, TW‐4, TW‐5, TW‐6, TW‐7, TW‐8, TW‐9, TW‐10, TW‐11, TW‐12, TW‐13 and TW‐14. These strains were identified by synthetically using colony morphological characters, physiological and biochemical tests and molecular biological analysis. Our results showed that these 14 isolated strains belonged to four genera and five species. The expected approximate 1400‐bp bands were obtained through 16S rDNA universal primer amplification. The sequencing results obtained from a commercial sequencing company were initially compared with a corresponding database from NCBI using BLAST, and a phylogenetic tree was constructed using mega 5.1 software. The phylogenetic results indicated that these isolated strains had more than 99% homology with type strains. To further confirm these strains, numerous physiological and biochemical indexes were confirmed. TW‐1, TW‐2, TW‐3, TW‐9, TW‐12, TW‐13 and TW‐14 were identified as Serratia marcescens; TW‐4, TW‐5, TW‐8 and TW‐10 as Staphylococcus sciuri; TW‐6 as Klebsiella pneumonia subsp. pneumonia; TW‐7 as Proteus vulgaris and TW‐11 as Proteus mirabilis. The preliminary single‐dose bioassay on fourth instar larvae showed that S. marcescens had a higher virulence at a density of 1.89 OD₆₀₀ (56.37% mortality) than the other strains. The corrected mortalities of the other strains were all less than 50%. The lowest toxicities were found for P. vulgaris and P. mirabilis where the corrected mortalities were only 28.18% and 25.57%, respectively. LC₅₀ of S. marcescens was 1.2 × 10⁷ CFU/ml inoculums. Our results indicated that S. marcescens from facultative cultivable bacterial flora isolated from R. ferrugineus could potentially be used as a microbial control agent for this widespread pest.     

Nicotine degradation by two novel bacterial isolates of <Emphasis Type="Italic">Acinetobacter</Emphasis> sp. TW and <Emphasis Type="Italic">Sphingomonas</Emphasis> sp. TY and their responses in the presence of neonicotinoid insecticides

Two novel nicotine-degrading bacterial strains were isolated from tobacco waste and identified as Acinetobacter sp. TW and Sphingomonas sp. TY based on morphology, physiological and biochemical tests, Biolog analysis and 16S rDNA sequencing. The 16S rDNA sequences have been deposited in GenBank under the accession numbers FJ753401 for TW and FJ754274 for TY. The best culture conditions for nicotine degradation were 25–37°C and pH 7.0–8.0 for strain TW and 25–30°C and pH 6.0–7.0 for strain TY. Under the best conditions, the cell growth and nicotine-degradation kinetics of the two isolates were assessed, and 1.0 g/l nicotine was completely degraded within 12 and 18 h for TW and TY, respectively. Moreover, the presence of four widely-used commercial neonicotinoid insecticides in the medium had no effects on nicotine degradation by TW; among the four tested neonicotinoids, only thiamethoxam significantly delayed nicotine degradation by TY. TW and TY were also able to degrade selected neonicotinoids. This is the first report of nicotine degradation by Acinetobacter sp. and Sphingomonas sp. This study showed that these two newly isolated bacteria may be suitable for the disposal of tobacco waste and the reduction of nicotine in tobacco leaves.     

Tea waste as a supplement for the cultivation of <Emphasis Type="Italic">Ganoderma</Emphasis> <Emphasis Type="Italic">lucidum</Emphasis>

Tea waste (TW) was investigated as a new supplement for substrate mixtures in Ganoderma lucidum cultivation. The effects of sawdust (S) based substrates supplemented with TW at the various levels (75S:25TW, 80S:20TW, 85S:15TW, and 90S:10TW) and Ganoderma lucidum strains on yield, biological efficiency (BE) and the chemical composition of fruiting bodies were determined in solid-state fermentation. Significant differences were found among substrates regarding yield and BE, while yield and BE of the strains were not different. The substrate formulations producing highest yield and BE were 80S:20TW (87.98 g/kg substrate and 34.90%) and 75S:25TW (82.30 g/kg substrate and 31%). Yield and BE of substrates containing TW were generally higher than that of the control (80sawdust:18wheat bran:1sucrose:1 CaCO₃). Nitrogen, potassium, iron, and manganese contents and C:N ratios of substrates were strongly correlated with yield. BE showed positive and significant correlations with potassium, iron and manganese. Moisture content, potassium, magnesium, calcium, iron, and zinc contents of the fruiting bodies were affected by both strain and substrate. It was concluded that TW can be used as a supplement for substrate preparation in G. lucidum cultivation.     

Halotolerant, alkaliphilic urease-producing bacteria from different climate zones and their application for biocementation of sand

Microbially induced calcium carbonate precipitation (MICP) is a phenomenon based on urease activity of halotolerant and alkaliphilic microorganisms that can be used for the soil bioclogging and biocementation in geotechnical engineering. However, enrichment cultures produced from indigenous soil bacteria cannot be used for large-scale MICP because their urease activity decreased with the rate about 5 % per one generation. To ensure stability of urease activity in biocement, halotolerant and alkaliphilic strains of urease-producing bacteria for soil biocementation were isolated from either sandy soil or high salinity water in different climate zones. The strain Bacillus sp. VUK5, isolated from soil in Ukraine (continental climate), was phylogenetically close in identity (99 % of 16S rRNA gene sequence) to the strain of Bacillus sp. VS1 isolated from beach sand in Singapore (tropical rainforest climate), as well as to the strains of Bacillus sp. isolated by other researchers in Ghent, Belgium (maritime temperate climate) and Yogyakarta, Indonesia (tropical rainforest climate). Both strains Bacillus sp. VS1 and VUK5 had maximum specific growth rate of 0.09/h and maximum urease activities of 6.2 and 8.8 mM of hydrolysed urea/min, respectively. The halotolerant and alkaliphilic strain of urease-producing bacteria isolated from water of the saline lake Dead Sea in Jordan was presented by Gram-positive cocci close to the species Staphylococcus succinus. However, the strains of this species could be hemolytic and toxigenic, therefore only representatives of alkaliphilic Bacillus sp. were used for the biocementation studies. Unconfined compressive strengths for dry biocemented sand samples after six batch treatments with strains VS1and VUK5 were 765 and 845 kPa, respectively. The content of precipitated calcium and the strength of dry biocemented sand at permeability equals to 1 % of initial value were 12.4 g Ca/kg of dry sand and 454 kPa, respectively, in case of biocementation by the strain VS1. So, halotolerant, alkaliphilic, urease-producing bacteria isolated from different climate zones have similar properties and can be used for biocementation of soil.     

Salt tolerance in Lycopersicon species. II. Genetic effects and a search for associated traits

Eleven quantitative traits, mostly related to tomato plant growth and fruit set, and their association with salt tolerance in terms of fruit yield under a 171.1 mM NaCl treatment have been investigated in 206 progeny derived from an interspecific hybrid, L. esculentum x L. pimpinellifolium, by self-pollination. None of the traits were highly correlated phenotypically to salt tolerance; however, the immunologically-detected presence of peptide 2 was significantly associated with high total fruit weight (TW) and number (FN) under saline treatment. Broad-sense heritability was estimated for these two salt-tolerance components as 53.44 and 72.59 %, respectively. Non-additive gene effects, which have to be considered in a breeding program for salt tolerance, have been detected in TW, FN and in average fruit weight (FW). Given that different types of gene action have been found depending on the presence or absence of a high NaCl concentration in the nutrient solution, a different set of genes, or genes, differently regulated, must be involved in the expression of TW, FN and other fruit-related characters depending on this environmental condition.     

Column Flushing of Phenanthrene and Copper (II) Co-Contaminants from Sandy Soil Using Tween 80 and Citric Acid

The clean-up of soils co-contaminated with heavy metals and organic compounds is a contemporary issue of remediation efforts. Column flushing was conducted to investigate the performance of nonionic surfactant and/or organic acid solutions, 4000 mg/L Tween 80 (TW80), and/or 0.04 mol/L citric acid (CA), to enhance the simultaneous removal of phenanthrene and copper (II) from the co-contaminated sandy soil. The flushing effects were compared when TW80, CA, TW80 after CA (CA/TW80), CA after TW80 (TW80/CA), and a mixture of TW80 and CA (TW80-CA) were used as flushing agents. The maximum concentrations of phenanthrene in effluent solutions occurred at 3.3, 4.7, 5.3, and 15.3 h during TW80, TW80/CA, TW80-CA, and CA/TW80 flushing and those of copper (II) at 2.7, 3.3, 3.3, and 14.0 h during CA, CA/TW80, TW80-CA, and TW80/CA flushing, respectively. Phenanthrene was mainly desorbed through partitioning into TW80 micelles in aqueous phase while copper (II) was effectively removed through complexation with CA. The removal efficiencies were up to 81.5%, 5.9%, 99.9%, 91.6%, and 99.8% for phenanthrene, and 0.1%, 76.7%, 85.7%, 78.1%, and 84.4% for copper (II) by TW80, CA, TW80/CA, TW80-CA, and CA/TW80. However, it took a long time to use TW80/CA and CA/TW80 to clean phenanthrene and copper (II) efficiently. The overall removal efficiencies of contaminants in the soil column increased with flushing time in the Sigmoidal Model. The results indicated that a combination of TW80 and CA has potential for in situ clean-up of heavy metals and polycyclic aromatic hydrocarbons (PAHs) from co-contaminated soils.     

Characteristics of DNA repair of a UV-sensitive mutant (radC) of Dictyostelium discoideum

Summary A radiation-sensitive mutant, TW8(radC), of Dictyostelium discoideum is more sensitive to ultraviolet light (UV) killing than the parental wild strain NC4(RAD ⁺), but is resistant to 4-nitroquinoline 1-oxide (4NQO) at almost the same level as NC4. In TW8 amoebae, single-strand breaks of DNA molecules were hardly detectable immediately after UV irradiation, and the removal of pyrimidine dimers was depressed during the postirradiation incubation when compared with that of NC4 amoebae. After treatment with 4NQO, however, single-strand breaks were detected in TW8 amoebae. The almost complete rejoining of these breaks was also detected after the removal of 4HAQO-adducts. The TW8 amoebae have an efficient repair capacity against DNA damage caused by 4NQO, MMS, MMC and MNNG but not UV.Abbreviations 4NQO 4-nitroquinoline 1-oxide - MMS methyl methanesulphonate - MMC mitomycin C - MNNG N-methyl-N-nitro-N-nitrosoguanidine     

The periodic motion of lodgepole pine trees as affected by collisions with neighbors

The periodic sways of a group of ten Pinus contorta var. latifolia (lodgepole pine) trees with slender stems from the Two Creeks site (TW) and ten stout trees from the Chickadee site (CH) both in Alberta, Canada were quantified. Tree displacement at TW was measured during periods of consistent wind direction with three mean wind speeds (1.9, 4.6, and 5.4 m/s) and for two mean wind speeds at CH (5.0 and 7.9 m/s). Spectral analysis of sway displacement data showed a decrease in the frequency with wind speed for trees at TW, but remained unchanged for trees at CH. Significant correlations between tree sway frequency and amplitude during high winds at TW indicate a loss of sway energy concomitant with the occurrence of high collision intensity. These observations support the hypothesis that inter-crown collisions have an important influence on the sway frequency of trees and should be incorporated into efforts to model their sway dynamics. We also present a theoretical collision-damped sway model which supports our empirical findings.     

Phycoremediation resultant lipid production and antioxidant changes in green microalgae Chlorella Sp.

In this investigation, we report on the treatment of tannery wastewater using microalgae Chlorella species to produce lipid and fatty acid as well as changes in antioxidant metabolism during the treatment. The variation in growth, production of pigments, antioxidant metabolism, lipid and fatty acids, and nutrient removal from wastewater during the remediation were observed. Surprisingly, a profuse growth was found in 50% diluted tannery wastewater (TW), which supported to accumulate high yield of lipid (18.5%) and unsaturated fatty acids (50.05%). The antioxidant activity of microalgae in both the concentrations (50% and 100% TW) were viz., lipid peroxidation 1.6 ± 0.1 and 2.3 ± 0.02nmol MDA mg^?1 protein, SOD 10.3 ± 0.4 and 15.7 ± 0.9 U mg^?1 protein, CAT 0.17 ± 0.036 and 0.52 ± 0.06 U mg^?1 protein, and APX 7.2 ± 0.8 and 11.2 ± 09 U mg^?1 protein respectively, which point out that the free radical scavenging mechanism against heavy metal stress. Maximum phycoremediation of heavy metals observed from both concentrations during the healthy growth period were Cr – 73.1, 45.7%, Cu – 90.4, 78.1%, Pb – 92.1, 52.2%, and Zn – 81.2, 44.6%, respectively. This study proved the potential use of Chlorella for heavy metal and nutrient removal from tannery wastewater. Moreover, an unaffected growth with high antioxidant activity of this species promises a sustainable lipid and fatty acid contents for biofuel production.     

Long‐distance dispersal or postglacial contraction? Insights into disjunction between Himalaya–Hengduan Mountains and Taiwan in a cold‐adapted herbaceous genus,Triplostegia

Current disjunct patterns can result from long‐distance dispersal or postglacial contraction. We herein investigate the evolutionary history of Triplostegia to elucidate the disjunction between the Himalaya–Hengduan Mountain region (HHM) and Taiwan (TW). Genetic structure of Triplostegia was investigated for 48 populations using sequences from five chloroplast loci and the ribosomal nuclear internal transcribed spacer. Divergence time estimation, ancestral area reconstruction, and species distribution modeling (SDM) were employed to examine the biogeographic history of Triplostegia. Substantial genetic differentiation among populations from southwestern China (SW), Central China (CC), and TW was detected. Triplostegia was inferred to have originated in SW, and diversification began during the late Miocene; CC was colonized in the mid‐Pliocene, and TW was finally colonized in the early Pleistocene. SDM suggested an expansion of climatically suitable areas during the Last Glacial Maximum and range contraction during the Last interglacial in Triplostegia. Disjunction between HHM and TW in Triplostegia is most likely the consequence of topographic isolation and postglacial contraction. The potential climatic suitability areas for Triplostegia by 2070s (2061–2080) are predicted to slightly shrink and move northward. With continued global warming and human‐induced deforestation, extinction risk may increase for the cold‐adapted species, and appropriate strategies should be employed for ecosystem conservation.     

Is TW3 height prediction more accurate than TW2? Preliminary data

BACKGROUND/AIMS: Skeletal maturation is considered a reliable variable in evaluating the 'tempo' of growth. It is important in the diagnosis of endocrinological diseases, in chronic diseases, in hormonal therapy follow-up and in computing height prediction for prognostic and therapeutic purposes. It is also used when chronological age is not available for minors without known birth dates. There are different methods to evaluate skeletal maturation and height prediction. The Tanner-Whitehouse (TW) method 2 (TW2) has been considered to be the most useful method so far, and has recently been updated with modified height prediction equations (TW2-Mark II). TW3 is the newest method. The aim of this study is to evaluate whether TW3 is more accurate in the assessment of height prediction than TW2-Mark II in a sample of healthy north Italian subjects. METHODS: Anthropometrical data were collected as part of a survey in 1977-1978 in Turin. The sample involved 1,384 healthy children. The children, now adults, have been traced and recalled to measure their final height in order to test height prediction reliability. At present, we have collected 118 adult heights. RESULTS: According to the TW2 method 40% of the males had a height prediction error larger than +/- residual SD (4.1 cm), and with TW3 this was 32.9%. The female height prediction error with TW2 was larger than +/- residual SD (3.6 cm) in 29.2% of girls, and the same value was found with TW3. CONCLUSION: According to our preliminary data, TW3 does not represent any real progress.     

Conditions for the trivers-willard hypothesis to be valid: A minimal population-genetic model

The very insightful Trivers-Willard hypothesis, proposed in the early 1970s, states that females in good physiological condition are more likely to produce male offspring when the variance of reproductive success among males is high. The hypothesis has inspired a number of studies over the last three decades aimed at its experimental verification, and many of them have found adequate supportive evidence in its favour. Theoretical investigations, on the other hand, have been few, perhaps because formulating a population-genetic model for describing the Trivers-Willard hypothesis turns out to be surprisingly complex. The present study is aimed at using a minimal population-genetic model to explore one specific scenario, namely how is the preference for a male offspring by females in good condition altered wheng, the proportion of such females in the population, changes from a low to a high value. As expected, when the proportion of such females in good condition is low in the population, i.e. for low values ofg, the Trivers-Willard (TW) strategy goes to fixation against the equal investment strategy. This holds true up to g_max, a critical value ofg, above which the two strategies coexist, but the proportion of the TW strategy steadily decreases asg increases to unity. Similarly, when the effect of well-endowed males attaining disproportionately high number of matings is more pronounced, the TW strategy is more likely to go to fixation. Interestingly, the success of the TW strategy has a complex dependence on the variance of the physiological condition of females. If the difference in the two types of conditions is not large, TW strategy is favoured, and its success is more likely as the difference increases. However, beyond a critical value of the difference, the TW strategy is found to be less and less likely to succeed as the difference becomes larger. Possible reasons for these effects are discussed. This paper is dedicated to the memory of W. D. Hamilton.     

A novel lipopeptide produced by a Pacific Ocean deep-sea bacterium, Rhodococcus sp. TW53

Aims: Our goal was to find a novel, biosurfactant‐producing bacterium from Pacific Ocean deep‐sea sediments. Methods and Results: An oil‐degrading biosurfactant‐producing bacterium TW53 was obtained from deep‐sea sediment, and was identified through 16S rDNA analysis as belonging to the genus Rhodococcus. It lowered the surface tension of its culture to 34·4 mN m^?1. Thin layer chromatography (TLC) showed that the crude biosurfactants of TW53 were composed of lipopeptides and free fatty acids (FA). The lipopeptides were purified with column chromatography and then hydrolysed with 6 mol l^?1 HCl. Gas chromatography‐mass spectrometry analysis showed that the hydrolyte in the hydrophobic fraction contained five kinds of FA with chain lengths of C₁₄–C₁₉, and C₁₆H₃₂O₂ was a major component making up 59·18% of the total. However, 3‐hydroxyl FA was not found, although it is usually found in lipopeptides. Silica gel TLC revealed that the hydrolyte in the hydrophilic fraction was composed of five kinds of amino acids; consistently, ESI‐Q‐TOF‐MS analysis confirmed the composition results and provided their sequence tentatively as Ala‐Ile‐Asp‐Met‐Pro. Furthermore, the yield and CMC (critical micelle concentrations) of purified lipopeptides were examined. The purified product reduced the surface tension of water to 30·7 mN m^?1 with a CMC value of 23·7 mg l^?1. These results suggest that Rhodococcus sp. TW53 produces a novel lipopeptide that we have named rhodofactin. Conclusion: The deep‐sea isolate Rhodococcus sp. TW53 was the first reported lipopeptide‐producing bacterium of this genus. The lipopeptides had novel chemical compositions. Significance and Impact of the Study: Rhodococcus sp. TW53 has potential in the exploration of new biosurfactants and could be used in bioremediation of marine oil pollution.     

Effect of environmental conditions on the production of two extracellular proteolytic enzymes byVibrio SA1

The production of two extracellular proteases, an endopeptidase and an aminopeptidase, by the marine bacteriumVibrio SA1 was studied in batch cultures. The production of the proteases was induced during growth of the organism in peptone media and by several amino acids during growth in minimal media. It was repressed by easily metabolisable carbon compounds such as glucose, lactate and succinate during growth in peptone media. During growth in a lactate basal medium, phenylalanine was one of the best inducers and this amino acid was therefore used in further experiments. That lactate dit not repress the synthesis of the proteases during growth in the lactate basal medium supplemented with 2mm phenylalanine as an inducer, appeared to be a consequence of the low iron content of this medium. Growth curves ofVibrio SA1 on such media showed a period of linear growth during which protease production was observed. When the iron concentration was made sufficiently high to prevent linear growth, the synthesis of the proteases remained repressed. Apparently by imposing an iron limitation on the organism, catabolite repression by lactate was relieved. Similarly, when growth was limited by very low values of the dissolved oxygen tension in the medium, a high rate of protease synthesis was found which was immediately repressed when the oxygen limitation was released. The results indicate that the growth rate and/or a factor associated with the energy metabolism play a role in the regulation of the synthesis of the enzymes.This study was supported by the Foundation for Fundamental Biological Research (BION), which is subsidised by the Netherlands Organization for the Advancement of Pure Research (ZWO).     

Requirement of chelating compounds for the growth of Corynebacterium glutamicum in synthetic media

Summary The effects of various iron-complexing substances on the growth of Corynebacterium glutamicum in synthetic medium were investigated. The data obtained indicate that C. glutamicum has an absolute requirement for the presence of an iron-complexing compound as a growth factor for rapid and abundabnt growth in synthetic media. This requirement can be met by adding low concentrations (10^–5 M) of certain dihydroxyphenols (catechol, protocatechuate) or relatively high concentratuions (0.1%) of citrate to the medium or by autoclaving a small amount of glucose together with other media components. The addition of catechol or protocatechuate to synthetic media has advantages over media preparation with citrate or autoclaved glucose. In the described synthetic broth supplemented with catechol or protocatechuate growth is largely independent of the iron content of the medium in a range between 0.037 and 0.37 mM.Offprint requests to: W. Liebl     

Lactose mother liquor as an alternative nutrient source for microbial concrete production by <Emphasis Type="Italic">Sporosarcina pasteurii</Emphasis>

Microbiologically induced calcite precipitation by the bacterium Sporosarcina pasteurii (NCIM 2477) using the industrial effluent of the dairy industry, lactose mother liquor (LML) as growth medium was demonstrated for the first time in this study. The urease activity and the calcite precipitation by the bacterium was tested in LML and compared with the standard media like nutrient media and yeast extract media. Calcite constituted 24.0% of the total weight of the sand samples plugged by S. pasteurii and urease production was found to be 353 U/ml in LML medium. The compressive strength of cement mortar was increased by S. pasteurii in all the media used compared to control. No significant difference in the growth, urease production and compressive strength of mortar among the media suggesting LML as an alternative source for standard media. This study demonstrates that microbial calcite acts as a sealing agent for filling the gaps or cracks and fissures in constructed facilities and natural formations alike.     

The capability of the algaeChlorella vulgaris andScenedesmus obliquus of utilizing amino acids as the sole nitrogen source

The capability of utilizing 20 amino acids and 2 amides as the sole nitrogen source for growth was studied in two green algae (Chlorophyceae). A comparison was made of the growth rate of algae in a mineral nutrient solution containing nitrate as the nitrogen source, with that in the same solution in which nitrogen in the form of nitrate was substituted by an equivalent nitrogen amount in the form of various amino acids. In addition to this, another series of experiments was carried out in whioh both culture media were supplied with glucose. The results show that both algae utilize a series of amino acids in dependence of their structure (mostly 3-carbon amino acids). The growth rate ofChlorella in the presence of these sources is the same as in nitrate, that ofScenedesmus even much higher. In the cultures containing glucose both algal species exhibit a higher growth rate in the media with the nitrate nitrogen source than in those with amino acids (with the exception of glycine inScenedesmus).