Production of large multienzyme complex by aerobic thermophilic fungus Chaetomium sp. nov. MS-017 grown on palm oil mill fibre

AIMS: A novel xylanolytic multienzyme complex of the aerobic thermophilic fungus Chaetomium sp. nov. MS-017 was produced on palm oil mill fibre (POMF) and partially characterized. METHODS AND RESULTS: The assay of the extracellular enzymes of Chaetomium sp. nov. MS-017 on POMF in solid-state fermentation revealed cellulolytic, pectinolytic and extremely high xylanolytic activities. The protein was purified by Sephadex G-200 column chromatography. The SDS-PAGE demonstrated that the purified protein is a complex with at least five xylanolytic, four cellulolytic and eight pectinolytic components. The characterization of the complex at various temperatures showed that the reactivity and stability of the complex are not lost up to 60 degrees C. In addition, the complex was very stable in a wide range of pH (3-9) and at high concentrations (10 mm) of cations and EDTA. The major products of xylan hydrolysis by the purified complex were determined to be xylobiose and xylotriose by thin-layer chromatography. CONCLUSION: Chaetomium sp. nov. MS-017 preferentially produces a xylanolytic multienzyme complex on POMF in solid-state fermentation. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report on the xylanolytic multienzyme complex produced by an aerobic thermophilic fungus.     

滇中亚高山人工林凋落物分解对模拟氮沉降的响应

2018年2月至2019年1月,利用尼龙网袋法对滇中亚高山华山松和云南松两种人工林开展模拟氮(N)沉降下凋落叶和凋落枝原位分解试验,N沉降水平分别为对照(CK, 0 g N·m^-2·a^-1)、低N(LN, 5 g N·m^-2·a^-1)、中N(MN, 15 g N·m^-2·a^-1)和高N(HN, 30 g N·m^-2·a^-1)。结果表明: 华山松凋落叶和凋落枝年分解率分别为34.8%和18.0%,分别高于云南松凋落叶的32.2%和凋落枝的16.1%。模拟N沉降下,LN处理使华山松凋落叶、枝分解95%所需时间较对照分别减少0.202和1.624年,MN处理分别减少0.045和1.437年,HN处理则分别增加0.840和2.112年;LN处理使云南松凋落叶、枝分解95%所需时间较对照分别减少0.766和4.053年,MN处理分别增加0.366和0.455年,HN处理分别增加0.826和0.906年。经过1年的分解,低N处理促进了华山松和云南松凋落物(叶、枝)的分解,而高N处理表现为抑制作用;N沉降对两种林型凋落物分解的影响与凋落物中纤维素和木质素含量密切相关。可见,凋落物基质质量在一定程度上决定了凋落物分解对N沉降的响应情况,尤其是纤维素和木质素含量。     

Fine root dynamic characteristics and effect on plantation’s carbon sequestration of three Salix shrub plantations in Tibetan Plateau alpine sandy land

Desertification land in Gonghe Basin of Tibetan Plateau, China accounts for 91.9% of the total land area. Vegetation restoration and reconstruction with desert shrubs in degraded ecosystem are effective ways to prevent and control desertification. However, the evaluation studies of fine root dynamic characteristics of desert shrubs and their contribution to carbon sequestration of plantation are limited. To gain a better understanding of vegetation restoration, the vertical distribution of fine root biomass, fine root decomposition, fine root turnover was investigated, as well as their coupling effect on carbon sequestration of plantation in three desert vegetation. The results estimated that the total decomposition time of fine roots of Salix cheilophila (S. cheilophila), Salix psammophila (S. psammophila), and Salix microstachya (S. microstachya) are 39.00, 27.99 and 35.95 years. Biomass carbon density for three Salix plantations ranged from 1.42 to 2.39 t/hm², which showed that three Salix plantations in alpine sandy land are an important carbon pool. In addition, fine root biomass carbon density for the three shrub plantations varied significantly. Fine root biomass carbon density for S. psammophila reached the largest among the three plantations, which was 1.48 t/hm², accounting for the ratio of 62% of the plantation total biomass carbon density. The results indicated that the root system of S. psammophila, especially the fine roots, was very developed, which was conducive to soil water transportation and carbon sequestration. Therefore, S. psammophila might be a better species for carbon sequestration of plantation in alpine sandy areas. The carbon input from the fine roots of the three shrub plantations through decomposition and turnover into the plantations accounts for 11.5% to 15.5% of total carbon sequestration of plantations. Therefore, the fine roots dynamics must be considered for long‐term carbon pool estimations in three Salix plantations, otherwise the total carbon sequestration of plantations would be underestimated.     

Comparison of two serologically distinct ribonucleic acid bacteriophages. II. Properties of the nucleic acids and coat proteins

Overby, L. R. (University of Illinois, Urbana), G. H. Barlow, R. H. Doi, Monique Jacob, and S. Spiegelman. Comparison of two serologically distinct ribonucleic acid bacteriophages. II. Properties of the nucleic acids and coat proteins. J. Bacteriol. 92:739-745. 1966.-The ribonucleic acid (RNA) molecules and coat proteins of two RNA coliphages, MS-2 and Qbeta, have been characterized. MS-2 RNA shows an S(20,w) of 25.8 and a molecular weight by light scattering of 10(6). The corresponding parameters for Qbeta-RNA were 28.9 and 0.9 x 10(6). A difference in base composition was reflected in the adenine-uracil ratio, which was 0.95 for MS-2 and 0.75 for Qbeta. The two RNA preparations are readily separated by chromatography on columns of methylated albumin. Both gave identical bouyant densities in cesium sulfate of 1.64 g/ml. The coat protein subunits were of similar molecular weights: 15,500 (Qbeta) and 14,000 (MS-2). They differed, however, in that the Qbeta-protein lacked tryptophan and histidine, whereas the MS-2 protein lacked only histidine.     

Litter decomposition and nutrient release in Acacia mangium plantations established on degraded soils of Colombia

Several factors control the decomposition in terrestrial ecosystems such as humidity, temperature, quality of litter and microbial activity. We investigated the effects of rainfall and soil plowing prior to the establishment of Acacia mangium plantations, using the litterbag technique, during a six month period, in forests plantations in Bajo Cauca region, Colombia. The annual decomposition constants (k) of simple exponential model, oscillated between 1.24 and 1.80, meanwhile k1 y k2 decomposition constants of double exponential model were 0.88-1.81 and 0.58-7.01. At the end of the study, the mean residual dry matter (RDM) was 47% of the initial value for the three sites. We found a slow N, Ca and Mg release pattern from the A. mangium leaf litter, meanwhile, phosphorus (P) showed a dominant immobilization phase, suggesting its low availability in soils. Chemical leaf litter quality parameters (e.g. N and P concentrations, C/N, N/P ratios and phenols content) showed an important influence on decomposition rates. The results of this study indicated that rainfall plays an important role on the decomposition process, but not soil plowing.     

<Emphasis Type="Italic">Sphingomonas jejuensis</Emphasis> sp. nov., isolated from marine sponge <Emphasis Type="Italic">Hymeniacidon flavia</Emphasis>

A Gram-negative, non-motile, rod shaped, and orange-pigmented chemoheterotrophic bacterium, strain MS-31^T was isolated from the marine sponge Hymeniacidon flavia, collected from near Jeju Island, Korea. The Strain MS-31^T was subjected to a polyphasic taxonomic study. The phylogenetic analysis based on the 16S rRNA gene sequences revealed that the novel isolate could be affiliated within the genus Sphingomonas. The strain MS-31^T showed 95.6% of 16S rRNA gene sequence similarity with the most closely related species Sphingomonas koreensis JSS26^T. The DNA G+C content of the strain MS-31^T was 69.4 mol%. The major isoprenoid quinone was ubiqunone 10 and predominant cellular fatty acids were summed feature 7 (comprising C_18:1 ω7c, C_18:1 Ω9t and/or C_18:1 ωl2t, 39.7%), C_16:0 (16.3%), C_14:0 2OH (15.9%) and summed feature 3 (comprising C_16:1 ω7c and/or C_15:0 iso 2OH, 11.7%). The polar lipids were sphingoglycolipid, phosphatidyletha-nolamine, phosphatidylglycerol, diphosphatidylglycerol and unidentified glycolipid. Based on the evidence from the polyphasic taxonomic study, the strain should be classified as a new species of the genus Sphingomonas. As a result, the name Sphingomonas jejuensis sp. nov. (type strain MS-31^T =KCTC 23321^T =NBRC 107775^T) is proposed.     

Wood decomposition in an abandoned beech and oak coppiced woodland in SE England

The rate of litter decomposition is often expressed as a constant decay rate (k; g g⁻¹ yr⁻¹) or as the time required for a certain percentage (often 95% and estimated as 3/k) of it to decompose (termed turnover time). Estimates of k may be obtained by determining the weight loss of litter in the field and also by assuming a steady state and obtaining the ratio of litter input: standing crop. Both methods were used to estimate decay rate and turnover times for beech and oak branches and twigs decomposing on the forest floor and these were critically evaluated.
Considerable variation, ranging between 1.8–144.5 yr, was found between the 95% turnover time estimates of various size components of the two species, obtained from woodfall and standing crop data. Likewise variation in decay rate of 2–2.5 cm diameter beech branches, estimated from field experiments, was large both between and within groups of branches categorised according to initial state of decay and presence or absence of bark. The mean annual decay rate for the various categories ranged between k = 0.165-0.452 g g⁻¹yr⁻¹. Branches without bark generally decomposed more slowly than those with bark. Beech twig (<0.5 cm diameter) decomposition rates, from field experiments, ranged between k = 0.149-0.220 g g⁻¹yr⁻¹ and variation was relatively low compared with that of branches. No significant differences (P<0.05)were detected between twig decomposition rates obtained from experiments initiated at different seasons although there was a slight decline in decay rate in winter months. Twig and branch decomposition rates fell within the range found in the few other comparable studies.     

Losses of soil carbon by converting tropical forest to plantations: erosion and decomposition estimated by δ13C

Indonesia lost more tropical forest than all of Brazil in 2012, mainly driven by the rubber, oil palm, and timber industries. Nonetheless, the effects of converting forest to oil palm and rubber plantations on soil organic carbon (SOC) stocks remain unclear. We analyzed SOC losses after lowland rainforest conversion to oil palm, intensive rubber, and extensive rubber plantations in Jambi Province on Sumatra Island. The focus was on two processes: (1) erosion and (2) decomposition of soil organic matter. Carbon contents in the Ah horizon under oil palm and rubber plantations were strongly reduced up to 70% and 62%, respectively. The decrease was lower under extensive rubber plantations (41%). On average, converting forest to plantations led to a loss of 10 Mg C ha^?1 after about 15 years of conversion. The C content in the subsoil was similar under the forest and the plantations. We therefore assumed that a shift to higher δ¹³C values in plantation subsoil corresponds to the losses from the upper soil layer by erosion. Erosion was estimated by comparing the δ¹³C profiles in the soils under forest and under plantations. The estimated erosion was the strongest in oil palm (35 ± 8 cm) and rubber (33 ± 10 cm) plantations. The ¹³C enrichment of SOC used as a proxy of its turnover indicates a decrease of SOC decomposition rate in the Ah horizon under oil palm plantations after forest conversion. Nonetheless, based on the lack of C input from litter, we expect further losses of SOC in oil palm plantations, which are a less sustainable land use compared to rubber plantations. We conclude that δ¹³C depth profiles may be a powerful tool to disentangle soil erosion and SOC mineralization after the conversion of natural ecosystems conversion to intensive plantations when soils show gradual increase of δ¹³C values with depth.     

模拟氮沉降对华西雨屏区天然常绿阔叶林凋落物木质素和纤维素降解的影响

从2013年11月至2014年11月,采用尼龙网袋法对华西雨屏区天然常绿阔叶林凋落物进行原位分解试验,模拟N(NH₄NO₃)沉降水平分别为对照(0 g N·m^-2·a^-1)、低氮沉降(5 g N·m^-2·a^-1)、中氮沉降(15 g N·m^-2·a^-1)和高氮沉降(30 g N·m^-2·a^-1),研究了N沉降对常绿阔叶林凋落物分解及其木质素和纤维素降解的影响.结果表明:华西雨屏区天然常绿阔叶林凋落物在夏季分解较快,明显快于其他季节.N沉降显著抑制了阔叶林凋落物的分解,抑制作用随N沉降量的增加而加强.N沉降使凋落物质量损失95%的时间与对照(4.81年)相比增加了0.53～1.88年.经过1 年的分解,中氮沉降和高氮沉降处理木质素和纤维素残留率显著高于对照,表明N沉降显著抑制了凋落物木质素和纤维素的降解.凋落物质量残留率与木质素和纤维素残留率呈显著正相关.N沉降抑制凋落物分解的原因可能是无机N的添加对木质素和纤维素的降解造成了阻碍.     

MS-222 (tricaine methane sulfonate) does not kill the amphibian chytrid fungus Batrachochytrium dendrobatidis

MS-222 (tricaine methane sulfonate) is an agent commonly used to anaesthetise or euthanize amphibians used in experiments. It is administered by immersing the animal to allow absorption through the skin. Chytridiomycosis is an important disease of amphibians and research involves experiments with live animals. Batrachochytrium dendrobatidis, the fungus which causes chytridiomycosis, is located in the skin and therefore the organism should come into contact with MS-222 when it is used. B. dendrobatidis is a sensitive organism which could possibly be killed by MS-222. Hence, results of chytridiomycosis studies in which MS-222 is used could be unreliable. A concentration of 2 g l(-1) and an exposure duration of 1 h is at the high end of the range at which MS-222 would be most commonly used. Exposure to 2 g l(-1) MS-222 for 1 h does not kill B. dendrobatidis cultures, suggesting that MS-222 is safe to use in chytridiomycosis studies.     

马尾松人工林林窗内凋落叶微生物生物量碳和氮的动态变化

目前,人工林普遍存在土壤退化、生物多样性降低等生态问题.人工抚育间伐,营造混交林是人们经营和管理人工林的主要方式之一.为了了解这种经营方式对人工林生态系统中养分循环的影响,本文研究了位于长江上游低山丘陵区的42年生马尾松人工林7种林窗(G₁: 100 m²、G₂: 225 m²、G₃: 400 m²、G₄: 625 m²、G₅: 900 m²、G₆: 1225 m²、G₇: 1600 m²)中马尾松和红椿凋落叶分解过程中微生物生物量碳和氮的动态变化.结果表明: 中小型林窗(G₁～G₅)有利于凋落叶分解过程中微生物生物量碳(MBC)和生物量氮(MBN)的增加.马尾松凋落叶中的MBC和MBN以及红椿凋落叶中的MBN,在分解期(360 d)内呈现出先增加后降低的变化,在180 d时三者达到最大值,其最高含量分别达到9.87、0.22和0.80 g·kg^-1.而红椿凋落叶中的MBC在分解90 d时即达到最大值44.40 g·kg^-1.红椿凋落叶中的MBC和MBN显著高于马尾松凋落叶.凋落叶中的微生物生物量碳和氮与日均温和凋落物的含水率显著相关,与凋落物的特性也密切相关.这说明对人工林进行抚育间伐时可将林窗控制在100～900 m²的范围内,有利于凋落叶分解过程中微生物生物量碳和氮的增加,加快凋落叶的分解,提高人工林林地的土壤肥力.     

Ectopic expression of a soybean phytase in developing seeds of <Emphasis Type="Italic">Glycine max</Emphasis> to improve phosphorus availability

A transgenic approach was used to alter soybean seed phytate content by expressing a soybean phytase gene (GmPhy) during seed development to degrade accumulating phytic acid (IP₆). An expression vector containing the soybean phytase cDNA controlled by the seed-specific -conglycinin promoter (-subunit) was used to transform embryogenic soybean cultures. Plants from four independent transgenic lines were analyzed for transgene integration and seed IP₆ levels. The reduction in IP₆ levels in transgenic seeds compared to control Jack soybeans ranged from 12.6 to 24.8 as determined by HPLC. A low copy transformant was propagated to the T₄ generation and examined in more detail for phytase expression and enzyme activity during seed development. Expression of phytase mRNA and phytase activity increased during seed development, consistent with the use of an embryo-specific promoter. Ectopic phytase expression during seed development offers potential as an effective strategy for reducing phytate content in soybean seed.     

Design,development and characterization of ACT017, a humanized Fab that blocks platelet's glycoprotein VI function without causing bleeding risks

Glycoprotein VI is a platelet-specific collagen receptor critical for in vivo formation of arterial thrombosis. It is also considered as an attractive target for the development of anti-thrombotic drugs because blocking glycoprotein (GP)VI inhibits platelet aggregation without inducing detrimental effects on physiologic hemostasis.

Here, we present data on the identification, in vitro and ex vivo pharmacology of a humanized Fab fragment designated as ACT017. ACT017 was selected out of 15 humanized variants based upon structural and functional properties. It was produced under GMP-like conditions followed by detailed physico-chemical analysis and functional characterization indicating high antigen-binding specificity and affinity. In addition, we demonstrate, in a dose-escalation study, that ACT017 has a high capacity to specifically inhibit collagen-induced platelet aggregation ex vivo after injection to the macaque without inducing thrombocytopenia, GPVI depletion or bleeding side effects as is the case for conventional anti-platelets. Therefore, ACT017 is a promising therapeutic candidate for the development of a new generation of safe and efficient anti-thrombotic drugs.     

A meta‐analysis of the effects of nutrient enrichment on litter decomposition in streams

The trophic state of many streams is likely to deteriorate in the future due to the continuing increase in human‐induced nutrient availability. Therefore, it is of fundamental importance to understand how nutrient enrichment affects plant litter decomposition, a key ecosystem‐level process in forest streams. Here, we present a meta‐analysis of 99 studies published between 1970 and 2012 that reported the effects of nutrient enrichment on litter decomposition in running waters. When considering the entire database, which consisted of 840 case studies, nutrient enrichment stimulated litter decomposition rate by approximately 50%. The stimulation was higher when the background nutrient concentrations were low and the magnitude of the nutrient enrichment was high, suggesting that oligotrophic streams are most vulnerable to nutrient enrichment. The magnitude of the nutrient‐enrichment effect on litter decomposition was higher in the laboratory than in the field experiments, suggesting that laboratory experiments overestimate the effect and their results should be interpreted with caution. Among field experiments, effects of nutrient enrichment were smaller in the correlative than in the manipulative experiments since in the former the effects of nutrient enrichment on litter decomposition were likely confounded by other environmental factors, e.g. pollutants other than nutrients commonly found in streams impacted by human activity. However, primary studies addressing the effect of multiple stressors on litter decomposition are still few and thus it was not possible to consider the interaction between factors in this review. In field manipulative experiments, the effect of nutrient enrichment on litter decomposition depended on the scale at which the nutrients were added: stream reach > streamside channel > litter bag. This may have resulted from a more uniform and continuous exposure of microbes and detritivores to nutrient enrichment at the stream‐reach scale. By contrast, nutrient enrichment at the litter‐bag scale, often by using diffusing substrates, does not provide uniform controllable nutrient release at either temporal or spatial scales, suggesting that this approach should be abandoned. In field manipulative experiments, the addition of both nitrogen (N) and phosphorus (P) resulted in stronger stimulation of litter decomposition than the addition of N or P alone, suggesting that there might be nutrient co‐limitation of decomposition in streams. The magnitude of the nutrient‐enrichment effect on litter decomposition was higher for wood than for leaves, and for low‐quality than for high‐quality leaves. The effect of nutrient enrichment on litter decomposition may also depend on climate. The tendency for larger effect size in colder regions suggests that patterns of biogeography of invertebrate decomposers may be modulating the effect of nutrient enrichment on litter decomposition. Although studies in temperate environments were overrepresented in our database, our meta‐analysis suggests that the effect of nutrient enrichment might be strongest in cold oligotrophic streams that depend on low‐quality plant litter inputs.     

Use of Aqueous Silver To Enhance Inactivation of Coliphage MS-2 by UV Disinfection

A synergistic effect between silver and UV radiation has been observed that can appreciably enhance the effectiveness of UV radiation for inactivation of viruses. At a fluence of ca. 40 mJ/cm², the synergistic effect between silver and UV was observed at silver concentrations as low as 10 μg/liter (P < 0.0615). At the same fluence, an MS-2 inactivation of ca. 3.5 logs (99.97%) was achieved at a silver concentration of 0.1 mg/liter, a significant improvement (P < 0.0001) over the ca. 1.8-log (98.42%) inactivation of MS-2 at ca. 40 mJ/cm² in the absence of silver. Modified Chick-Watson kinetics were used to model the synergistic effect of silver and UV radiation. For an MS-2 inactivation of 4 logs (99.99%), the coefficient of dilution (n) was determined to be 0.31, which suggests that changes in fluence have a greater influence on inactivation than does a proportionate change in silver concentration.     

Molecular properties of metal difluorides and their interactions with CO<Subscript>2</Subscript> and H<Subscript>2</Subscript>O molecules: a DFT investigation

A computational study of metal difluorides (MF₂; M = Ca to Zn) and their interactions with carbon dioxide and water molecules was performed. The structural parameter values obtained and the results of AIM analysis and energy decomposition analysis indicated that the Ca–F bond is weaker and less ionic than the bonds in the transition metal difluorides. A deformation density plot revealed the stablizing influence of the Jahn–Teller effect in nonlinear MF₂ molecules (e.g., where M= Sc, Ti, Cr). An anaysis of the metal K-edge peaks of the difluorides showed that shifts in the edge energy were due to the combined effects of the ionicity, effective nuclear charge, and the spin state of the metal. The interactions of CO₂ with ScF₂ (Scc3 geometry) and TiF₂ (Tic2 geometry) caused CO₂ to shift from its usual linear geometry to a bent geometry (η²(C=O) binding mode), while it retained its linear geometry (η¹(O) binding mode) when it interacted with the other metal difluorides. Energy decomposition analysis showed that, among the various geometries considered, the Scc3 and Tic2 geometries possessed the highest interaction energies and orbital interaction energies. Heavier transition metal difluorides showed stronger affinities for H₂O, whereas the lighter transition metal (Sc and Ti) difluorides preferred CO₂. Overall, the results of this study suggest that fluorides of lighter transition metals with partially filled d orbitals (e.g., Sc and Ti) could be used for CO₂ capture under moist conditions.

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Graphical abstract Interaction of metal difluorides with carbon dioxide and water

     

A life cycle assessment case study for walnut tree (<Emphasis Type="Italic">Juglans regia</Emphasis> L.) seedlings production

Purpose  

High-quality wood production is based on both natural forestry populations and dedicated tree plantations, also mentioned as industrial plantations. The establishment of dedicated plantations needs high-quality seedlings, often grown in a nursery, having specific genetic and morphological features. From seed gathering to final selling, the growth of the seedlings needs human interventions and specific inputs such as fertilizers, pesticides, substrates, and capital goods (e.g., pots and greenhouses). All these inputs of course can cause not negligible environmental impacts, due to their production, maintenance, and final disposal. For these reasons, the environmental impact due to seedlings production in a nursery deserves deep analysis to assess the overall impact linked to wood supply chain: it is important that wood products are able to meet high environmental standards. This study is focused on 1- and 2-year-old walnut tree (Juglans regia L.) seedlings, aimed to high-quality timber production.     

Exploring low-cost carbon sources for microbial lipids production by fed-batch cultivation of <Emphasis Type="Italic">Cryptococcus albidus</Emphasis>

Volatile fatty acids (VFAs), acetic acid, acetates, and ethanol were used as carbon sources for the production of microbial lipids using Cryptococcus albidus in batch cultures. C. albidus utilized organic acids less than glucose in the production of lipids, resulting in a lipid yield coefficient on VFAs of 0.125 g/g. In a two-stage batch culture, the lipid content increased to 43.8% (w/w) when VFAs were used as the sole carbon source in the second stage, which was two times higher than that of the batch culture. Furthermore, a 192 h, two-stage fed-batch cultivation of C. albidus produced a dry cell weight, lipid concentration, and lipid content of 26.4 g/L, 14.5 g/L, and 55.1% (w/w), respectively. The fed-batch culture model used in this study featured pure VFA solutions, with intermittent feeding, under oxygen-enriched air supply conditions. This study investigated several alternative carbon sources to reduce the cost of microbial lipids production and proved the feasibility of using VFAs as the carbon source for the provision of a high lipid content and productivity.     

Antifungal Activity of Crude Extracts of <i>Tectona grandis</i> L.f. against Wood Decay Fungi

Wood is mainly made up of cellulose, hemicelluloses, lignin polymers and other organic and inorganic substances, making it susceptible to deteriorate by various biological agents. Tectona grandis L.f. (Teak) is a timber species with high resistance to biological deterioration, valued for its durability, beauty, and mechanical resistance. The purpose of this work was to evaluate the antifungal activity of crude extracts from teak on various fungi that cause wood deterioration. For this, Teak heartwood was obtained, then fragmented and pulverized until obtaining a flour which was used for compounds extraction using the Soxhlet technique coupled to a rotary evaporator through solvents of increasing polarity (hexane, dichloromethane, tetrahydrofuran, and acetone). The extracts obtained were tested against fungal organisms collected in the field, and the LC₅₀ was determined using teak crude extracts on Artemia salina as a biological model. The results obtained showed that a high flour yield was obtained with hexane (0.951 g), followed by tetrahydrofuran (0.446 g), dichloromethane (0.348 g), and acetone (0.152 g). By using nine fungal organisms that predominantly correspond to the genus Aspergillus, the extractable compounds were tested, inhibiting 25% of mycelial growth with tetrahydrofuran (T. versicolor), and 40.9% with dichloromethane (G. trabeum). Likewise, the biological model of A. salina showed an LC₅₀ of 84.9 μg/mL with hexane, 43.3 μg/mL with dichloromethane, 59.6 μg/mL with tetrahydrofuran, and 54.7 μg/mL with acetone. For this reason, it is concluded that Teak wood contains many extractable compounds in relation to its weight, besides having antimicrobial activity when extracted through polar compounds such as dichloromethane and tetrahydrofuran.     

Isolation and characterization of a novel 2-<Emphasis Type="Italic">sec</Emphasis>-butylphenol-degrading bacterium <Emphasis Type="Italic">Pseudomonas</Emphasis> sp. strain MS-1

A novel bacterium capable of utilizing 2-sec-butylphenol as the sole carbon and energy source, Pseudomonas sp. strain MS-1, was isolated from freshwater sediment. Within 30 h, strain MS-1 completely degraded 1.5 mM 2-sec-butylphenol in basal salt medium, with concomitant cell growth. A pathway for the metabolism of 2-sec-butylphenol by strain MS-1 was proposed on the basis of the identification of 3 internal metabolites—3-sec-butylcatechol, 2-hydroxy-6-oxo-7-methylnona-2,4-dienoic acid, and 2-methylbutyric acid—by gas chromatography-mass spectrometry analysis. Strain MS-1 degraded 2-sec-butylphenol through 3-sec-butylcatechol along a meta-cleavage pathway. Degradation experiments with various alkylphenols showed that the degradability of alkylphenols by strain MS-1 depended strongly on the position (ortho ≫ meta = para) of the alkyl substitute, and that strain MS-1 could degrade 2-alkylphenols with various sized and branched alkyl chain (o-cresol, 2-ethylphenol, 2-n-propylphenol, 2-isopropylphenol, 2-sec-butylphenol, and 2-tert-butylphenol), as well as a dialkylphenol (namely, 6-tert-butyl-m-cresol).