Growth and toxin production by Clostridium botulinum in moldy tomato juice.

Tomato juice inoculated with Cladosporium sp. or Penicillium sp. developed pH gradients with the upper portions near the mold mats having pH values near neutrality and the lower portions remaining more acid. Clostridium botulinum spores in these moldy tomato juices germinated, grew out, and produced toxin.     

Crithidia mellificae n. sp. an Acidophilic Trypanosomatid of the Honey Bee Apis mellifera

SYNOPSIS. Crithidia mellificae n. sp. is described from the honey bee Apis mellifera in apiaries of Victoria, Australia. Organisms were isolated and cultured in a modified NNN medium with Cowper-thwaite's medium as an overlay. In contrast to other isolates of Crithidia, C. mellificae grows best at a pH between 4.5 and 5.5 with optimum near pH 5. In Cowperthwaite's medium alone, buffered at pH 4.5–5.5, the organism will survive apparently indefinite passages. The organism has so far as known, no pathologic effects in the hymenopteran host.     

Fine structure of the chemoreceptor sensillum in Limulus

Each chemoreceptor sensillum of Limulus polyphemus consists of 6–15 bipolar neurosensory cells with distal processes confined within a single cuticular tubule as they extend to the outside environment. The cuticular tubule, which is enveloped by the cuticulo-tubal cell, opens proximally into a fluid-filled extracellular space through which the dendrite passes before entering the cuticular tubule. Between the neurosensory cells are one to three microvillar cells also exposed to the extracellular space. This space is enclosed by a sheath cell extending proximally from the inner opening of the cuticular tubule and enveloping the proximal portions of the dendrites, the distal portions of the microvillar cells, as well as the distal portion of some neurosensory cell bodies. Most of the remaining portions of the neurosensory cells and microvillar cells are enveloped by neuroglia. Tight junctions occur between the distal portions of the dendrites in or near the cuticular tubule. Each dendrite has a cilium-like segment located where it traverses the extracellular space with a 9 + 0 pattern of fibers. Septuplelayered junctions occur among the proximal portions of some dendrites and some neurosensory cell bodies of the same sensillum. The subjacent processes of the sensillum frequently course proximally as isolated axons before joining nerve bundles. In the chilarial and gnathobasal chemoreceptors these nerve bundles course proximally to neuropile clumps of a peripheral nerve plexus. The presence of numerous synaptic vesicles in the neuropiles suggests that chemical transmission may occur among “en passant” synapses formed by the axons. Proximally the neuropiles are joined to the central nervous system by relatively long nerves.     

Direct measurement of ph within marine biofilms on passive metals

Direct measurements of the pH within natural marine biofilms grown on platinum have been made with iridium/iridium oxide solid‐state microelectrodes. The data show that the pH is highly variable, with steep gradients both perpendicular to and along the metal surface. Measured values ranged from 8 in the outer portions of the biofilm to below 2 in localized areas near the metal surface. It was verified that bulk water flowing along the hydrophilic outer sheath of the micro‐electrode could effect the measured pH values. However, meaningful data could still be taken because the response time of the electrode was sufficiently less than the time for water ingression. The data presented are consistent with recent heterogeneous biofilm models and with the idea that localized areas of low pH within biofilms can be a contributing factor in biologically influenced corrosion processes.     

Chemical Fractionation and Soil-to-Plant Transfer Characteristics of Heavy Metals in a Sludge Deposit Field of the River Ruhr,Germany

The presented study assessed the heavy metal contamination risk in a former sludge deposit field of the River Ruhr in Essen, Germany. Therefore, the temporal and spatial distribution in soils and plants, chemical fractionation, mobilization potential, and transfer characteristics have been investigated. Soil samples, roots and shoots of rushes (Juncus sp.), and stem wood disks of willows (Salix sp.) were analyzed for Zn, Cu, Pb, Ni, Cr, and Cd. Plant available and mobile heavy metal portions have been determined using a sequential extraction procedure. The results show that the soils and the rushes are highly contaminated, although there is a considerable decrease compared to initial concentrations some 20 years ago. The willows show only small heavy metal enrichment. pH induced mobilization potential in soil is high for Cd, Zn and Ni. Additionally, these elements contain high portions of plant-available fractions. High transfer rates from soil to roots and very high rates from roots to shoots of rushes have been determined for Cd and Zn, indicating an accumulation of these elements in shoots of rushes. The rushes reflect the temporal and spatial heavy metal distribution in soil and might thus be used as a bioindicator or for phytoremediation.     

Germination of Erysiphe gratninis f.sp. hordei conidia on barley leaves

Germination of Erysiphe graminis f.sp. hordei conidia on leaves of several barley cultivars was studied in the laboratory. On both detached leaves and intact plants, within 48 h of inoculation a higher proportion of conidia had germinated on the basal and middle portions of the adaxial leaf surface than on the corresponding portions of the abaxial surface. Such differences between surfaces were not observed near the leaf tip. Similar results were obtained with all the cultivars and growth stages tested, and with five isolates of E. graminis, and are consistent with the observation that there is usually less powdery mildew on the abaxial than the adaxial surface of barley leaves. With most of the barley genotype/mildew isolate combinations tested, within 48 h of inoculation higher proportions of conidia germinated on seedlings and juvenile plants than on older plants. Inherited characteristics which affect spore germination on the leaf surface may be important factors in the development of adult-plant resistance of barley to powdery mildew, particularly in certain genotypes.     

Fungal succession and decomposition of <Emphasis Type="Italic">Camellia japonica</Emphasis> leaf litter

Decomposition processes of Camellia japonica leaf litter were investigated over an 18-month period with reference to the role of fungal succession in the decomposition of lignin and holocellulose. Decomposition and fungal succession were studied in bleached and nonbleached portions of litter, which were precolonized by ligninolytic and cellulolytic fungi, respectively. Coccomyces nipponicum and Lophodermium sp. (Rhytismataceae), which can attack lignin selectively, caused mass loss of lignin and were responsible for bleaching during the first 4 months (stage I), whereas cellulolytic fungi caused mass loss of holocellulose in adjacent nonbleached portions. Soluble carbohydrates and polyphenols also decreased rapidly during this stage. Pestalotiopsis guepini, coelomycete sp.1, and the Nigrospora state of Khuskia oryzae caused mass loss of holocellulose between 4 and 14 months (stage II) and Xylaria sp. caused mass loss of both lignin and holocellulose from 14–18 months (stage III). In stages II and III, decomposition was more rapid in bleached portions than in nonbleached portions probably due to the prior delignification of lignified holocellulose in bleached portions. Frequencies of these fungi showed different responses among species to the pattern of changes in lignin and holocellulose contents during decomposition. Total hyphal length increased in both portions over the study period, but mycelia of basidiomycetes accounted for about 2% of total hyphal length, suggesting that their role in fungal succession and decomposition was low. Lignin and nitrogen contents were consistently lower and holocellulose content was higher in bleached portions than in nonbleached portions during decomposition. The succession of ligninolytic and cellulolytic fungi was a major driving factor that promoted decomposition and precolonization by ligninolytic fungi enhanced decomposition.     

受白粉菌诱导大麦抗感等基因系蛋白质变化的双向电泳分析

分别对接种与否的大麦抗—感白粉病等基因系—叶期幼苗取材进行蛋白质双向电泳分析。结果表明,病原的侵入使抗—感两系在30Kd以下的低分子量区域的蛋白质发生了明显变化。接种48小时之后,抗病系在pH5.5、6.0、6.8及8.8附近出现了对照中所没有的蛋白质,而在pH6.0和8.8附近的蛋白质则较对照有减小的趋势;感病系在pH6.0附近蛋白质明显增多,在pH8.8处不仅在量上有大幅度提高,而且种类也有增加。结果还表明,抗—感系间在未接种的情况下双向电泳图谱也有差异,接种之后由于感病系在pH8.8处蛋白质的特异性合成,使抗—感两系间的差异缩小。     

吉林省蓝藻门真枝藻属三新种

报道了采自吉林省的蓝藻门真枝藻属三新种：波纹真枝藻,拟小真枝藻,悦目真枝藻。波纹真枝藻丝体边缘常呈波纹状,主丝体宽 80～100 μm;拟小真枝藻主丝体宽 60～80 μm,分枝宽 30～45 μm,其胶被幼时黄褐色,成熟后无色;悦目真枝藻的匍匐丝体由数条丝体通过侧面粘合在一起,每条丝体宽 15～26 μm。     

Characterization of a novel polyphenol-specific oligoxyloside transfer reaction by a family 11 xylanase from Bacillus sp. KT12

A culture filtrate of Bacillus sp. KT12 was used to prepare polyphenyl beta-oligoxylosides from xylan and polyphenols in a one-step reaction. One oligoxyloside transfer enzyme was purified from multiple xylanolytic enzymes in the culture filtrate. N-terminal amino acid sequence determination classified the enzyme as a glycosyl hydrolase family 11 (endo-xylanase). The xylanolytic enzyme activities could be markedly altered; its hydrolytic activity was almost entirely inhibited at acidic pH, whereas near constant transxylosylation activity was observed at pH 4-11. Further, metal ions activated transxylosylation and almost completely inhibited hydrolysis. The enzyme specifically induced a beta-xylosyl transfer reaction to acceptor molecules, such as divalent and trivalent phenolic hydroxyl groups, and displayed no activity toward alcoholic compounds. The Bacillus sp. KT12 xylanolytic enzyme was a suitable enzyme for the synthesis of polyphenyl beta-oligoxylosides.     

The Food Web of Boiling Springs Lake Appears Dominated by the Heterolobosean Tetramitus thermacidophilus Strain BSL

We studied the protist grazers of Boiling Springs Lake (BSL), an acid geothermal feature in Lassen Volcanic National Park, using a combination of culture and genetic approaches. The major predator in BSL is a vahlkampfiid ameba closely related (95% 18S+ITS rRNA identity) to Tetramitus thermacidophilus, a heterolobose ameboflagellate recently isolated from volcanic geothermal acidic sites in Europe and Russia, as well as an uncultured heterolobosean from the nearby Iron Mountain acid mine drainage site. Tetramitus thermacidophilus strain BSL is capable of surviving the physical extremes of BSL, with optimal growth at 38–50 °C and pH 2–5. This bacterivore also ingested conidiospores of the ascomycete Phialophora sp., but ultrastructural observations reveal the latter may not be readily digested, and conidia were not separable from the ameoboflagellate culture, suggesting a possible symbiosis. DGGE fingerprint transects studies showed the organism is restricted to near‐lake environs, and we detected an average of ~500 viable cysts/cm³ sediment on the shoreline. Other grazing protists were isolated from lakeshore environments, including the lobose amebae Acanthamoeba sp. and Hartmannella sp., and the kinetoplastid flagellate Bodo sp., but none could tolerate both low pH and high temperature. These appear to be restricted to cooler near lake geothermal features, which also contain other potential grazer morphotypes observed but not successfully cultured, including ciliates, euglenids, testate amebae, and possible cercozoans. We compare the food web of BSL with other acidic or geothermal sites, and discuss the impact of protists in this unique environment.     

酯酶产生菌的分离与酶学性质研究

从餐馆附近下水道收集到的土壤中分离获得6株酯酶产生菌,其中S2菌株活性最高,从其形态特征、生理生化试验以及16S rRNA序列分析等方面,初步鉴定S2菌株为假单胞属(Pseudomonas sp.)。对该菌株的部分酶学性质进行了研究,发现该菌株所产的酯酶最适反应温度为40℃,最适反应pH为8.0;且该酯酶在温度为60℃以下和pH 7.0～10.0具有良好的稳定性。     

Directed evolution of a maltogenic alpha-amylase from Bacillus sp. TS-25

Directed evolution coupled with a high-throughput robotic screen was employed to broaden the industrial use of the maltogenic alpha-amylase Novamyl from Bacillus sp. TS-25. Wild-type Novamyl is currently used in the baking industry as an anti-staling agent in breads baked at neutral or near neutral pH. However, the enzyme is rapidly inactivated during the baking process of bread made with low pH recipes and Novamyl thus has very limited beneficial effect for this particular application. In an effort to improve the performance of Novamyl for low pH bread applications such as sourdough and rye, two error-prone PCR libraries were generated, expressed in Bacillus subtilis and screened for variants with improved thermal stability and activity under low pH conditions. Variants exhibiting improved performance were iteratively recombined using DNA shuffling to create two generations of libraries. Relative to wild-type Novamyl, a number of the resulting variants exhibited more than 10 degrees C increase in thermal stability at pH 4.5, one of which demonstrated substantial anti-staling properties in low pH breads.     

Nucleotide sequence of the Synechococcus sp. PCC7942 branching enzyme gene (glgB): expression in Bacillus subtilis

The nucleotide sequence of the Synechococcus sp. PCC7942 glgB gene has been determined. The gene contains a single open reading frame (ORF) of 2322 bp encoding a polypeptide of 774 amino acids (aa) with an Mr of 89,206. Extensive sequence similarity exists between the deduced aa sequence of the Synechococcus sp. glgB gene product and that of the Escherichia coli branching enzyme in the middle portions of the proteins (62% identical aa). In contrast, the N-terminal portions shared little homology. The sequenced region which follows glgB contains an ORF encoding 79 aa of the N terminus of a polypeptide that shares extensive sequence similarity (41% identical aa) with human and rat uroporphyrinogen decarboxylase. This suggests that the region downstream from glgB contains the hemE gene and, therefore, that the organization of genes involved in glycogen biosynthesis in Synechococcus sp. is different from that described for E. coli. A fusion gene was constructed between the 5' end of the Bacillus licheniformis penP gene and the Synechococcus sp. glgB gene. The fusion gene was efficiently expressed in the Gram+ micro-organism Bacillus subtilis and specified a branching enzyme with an optimal temperature for activity similar to the wild-type enzyme.     

Biological consequences of stream routing through a final-cut Strip mine pit: Benthic macroinvertebrates

Benthic macroinvertebrates were collected from the Plachek Pit, a final-cut coal strip mine pit at the Big Horn Mine near Sheridan, Wyoming, USA. Goose Creek was routed through the pit to allow mining under the original creek bed. The benthic community in the pit was dominated by the worm Limnodrilus hoffmeisteri and various midge genera, including Chironomus sp., Procladius sp. and Tanypus stellatus. Insects other than chironomids were minor components of the benthic fauna, and were collected only in the upstream portions of the pit; they were concluded to have originated from drift deposition. The pit functions as a sink for drifting macroinvertebrates. Based on community composition and supplemental water quality information it was concluded that the Plachek Pit best exemplified an organically-enriched, lake-like ecosystem. Overall, rerouting of Goose Creek through the Plachek Pit was not viewed as deleterious to Goose Creek, but rather benefited the creek by serving as a sink for inputs from upstream municipal and agricultural effluents.     

Construction and characterization of the chimeric enzymes between the Bacillus subtilis cellulase and an alkalophilic Bacillus cellulase

The amino acid sequences of cellulase from Bacillus subtilis (BSC) and that from an alkalophilic Bacillus sp. N-4 (NK1) show significant homology in most parts except for the C-terminal portions. Despite the high homology, the pH activity profiles of the two enzymes are quite different; BSC has its optimum pH at 6-6.5, whereas NK1 is active over a broad pH range from 6 to 10.5. In order to identify the structural features which determine such pH activity profiles, chimeric cellulases between BSC and NK1 were constructed using four restriction sites commonly present within the homologous coding sequences, and were produced in Escherichia coli. The chimeric cellulases showed various chromatographic behaviors, reflecting the origins of their C-terminal regions. The pH activity profiles of the chimeric enzymes in the alkaline range could be classified into either the BSC or NK1 type mainly depending on the origins of the fifth C-terminal regions. In the acidic range, the profile was determined only by the origin of the fourth enzyme region from the N terminus. Comparison of the kinetic parameters between pH 5 and 6 using p-nitrophenyl cellobioside as a substrate indicated that the fourth region is responsible for the pH-dependent change of the kcat value. Only a limited number of amino acids in the fourth region may affect on deprotonation of catalytic residues of the cellulases and modulate the catalytic activity in the acidic pH values.     

pH对小球藻Chlorella sp. XQ-200419光合作用、生长和产油的影响

以一种生长快、油脂含量高的小球藻(Chlorella sp. XQ-200419)为实验材料, 利用测定净光合放氧速率的方法研究了pH对其光合作用的影响; 使用改良的BG-11培养基在微藻环形培养池模拟系统中进行分批培养, 培养周期为8d, 培养过程中使用 pH控制仪在线监测藻液的pH, 根据pH变化, 自动接通、关闭CO2通气管道, 将藻液pH分别控制在5.06.0, 7.08.0, 8.09.0, 9.010.0, 10.011.0内, 研究pH对生长速率、生物质面积产率、总脂含量和总脂面积产率的影响。主要结果如下: 藻液pH对小球藻Chlorella sp. XQ-200419光合放氧、生长速率、生物质产率、总脂含量和产率都有显著影响, 适宜的pH范围是7.09.0, 在此范围内, 光合放氧、生长速率、生物质产率、总脂含量和产率均保持较高水平, 且pH的影响不显著; pH低于7.0, 高于9.0, 其光合放氧、生长速率、生物质产率、总脂含量和产率都显著降低。这表明pH对小球藻Chlorella sp. XQ-200419光合作用的影响和对生长、产油的影响是一致的。pH 7.08.0, 小球藻的生物质平均面积产率和总脂平均面积产率都达到最大值, 分别是8.9 g/(m2d)和2269.5 mg/(m2d); 当藻液pH超过10.0, 生物质平均面积产率和总脂平均面积产率分别降低42.1%和60.0%。适合于小球藻生长的pH也有利于其积累油脂, 所以, pH对小球藻产油的影响是一种适宜模式, 而非胁迫模式。规模化培养小球藻Chlorella sp. XQ-200419, 通过补充CO2将藻液pH控制在7.09.0内, 可以获得高生物质产率和总脂产率。研究结果反映出pH对小球藻光合作用、生长和产油影响的规律, 也为规模化培养小球藻生产微藻油脂过程中合理控制藻液pH提供了依据。       

Different behavior towards raw starch of three forms of glucoamylase from a Rhizopus sp

Three forms of glucoamylase [EC 3.2.1.3] of a Rhizopus sp., Gluc1 (M.W. 74,000), Gluc2 (M.W. 58,600), and Gluc3 (M.W. 61,400), which have similar pH optima and specific activities towards soluble starch were studied as to their behavior towards raw starch. The pH optima for raw starch digestion were different, that is, 4.5 for Gluc1 and 5.0 for both Gluc2 and Gluc3. All the enzymes digested raw starch almost completely but at quite different rates; Gluc2 and Gluc3, which lack the N-terminal portions of Gluc1, were 22 and 25 times less effective, respectively, for raw starch digestion than Gluc1. Of the three enzymes, only Gluc1 tightly bound to raw starch. Binding of Gluc1 to raw starch occurred pH-dependently with a broad pH optimum of 4.5-5.5, but temperature and ionic strength affected it only slightly and little, respectively. The binding constant of Gluc1 for raw starch at pH 5.0 and 4 degrees C was estimated to be 1.2 X 10(5) M-1. Fragment H (M.W. 16,700), presumably released from the N-terminal part of Gluc1, not only bound to raw starch itself but also inhibited the binding of Gluc1 to raw starch. pap-Gluc (M.W. 57,000) and chymo-Gluc (M.W. 64,000), which are papain- and chymotrypsin-modified Gluc1, respectively, and lack the N-terminal portions of Gluc1, resembled Gluc2 and Gluc3 in raw starch binding as well as digestion. All these results indicate that Gluc1 has a raw starch-binding site, different from the active center, in the N-terminal region. Various substrates and analogs inhibited the binding of Gluc1 to raw starch, presumably due to steric hindrance.     

A specific adaptation in the a subunit of thermoalkaliphilic F1FO-ATP synthase enables ATP synthesis at high pH but not at neutral pH values

Analysis of the atp operon from the thermoalkaliphilic Bacillus sp. TA2.A1 and comparison with other atp operons from alkaliphilic bacteria reveals the presence of a conserved lysine residue at position 180 (Bacillus sp. TA2.A1 numbering) within the a subunit of these F(1)F(o)-ATP synthases. We hypothesize that the basic nature of this residue is ideally suited to capture protons from the bulk phase at high pH. To test this hypothesis, a heterologous expression system for the ATP synthase from Bacillus sp. TA2.A1 (TA2F(1)F(o)) was developed in Escherichia coli DK8 (Deltaatp). Amino acid substitutions were made in the a subunit of TA2F(1)F(o) at position 180. Lysine (aK180) was substituted for the basic residues histidine (aK180H) or arginine (aK180R), and the uncharged residue glycine (aK180G). ATP synthesis experiments were performed in ADP plus P(i)-loaded right-side-out membrane vesicles energized by ascorbate-phenazine methosulfate. When these enzyme complexes were examined for their ability to perform ATP synthesis over the pH range from 7.0 to 10.0, TA2F(1)F(o) and aK180R showed a similar pH profile having optimum ATP synthesis rates at pH 9.0-9.5 with no measurable ATP synthesis at pH 7.5. Conversely, aK180H and aK180G showed maximal ATP synthesis at pH values 8.0 and 7.5, respectively. ATP synthesis under these conditions for all enzyme forms was sensitive to DCCD. These data strongly imply that amino acid residue Lys(180) is a specific adaptation within the a subunit of TA2F(1)F(o) to facilitate proton capture at high pH. At pH values near the pK(a) of Lys(180), the trapped protons readily dissociate to reach the subunit c binding sites, but this dissociation is impeded at neutral pH values causing either a blocking of the proposed H(+) channel and/or mechanism of proton translocation, and hence ATP synthesis is inhibited.     

AN UNUSUAL NEW SPECIES OF DRAPARNALDIA FROM LAKE CHAMPLAIN1,2,3

Draparnaldia champlainensis sp. nov. is described and compared with other species of the genus and with Draparnaldiopsis. It closely resembles certain species described by Meyer from Lake Baikal and also Draparnaldiopsis simplex Jao. Its distinguishing features are (1) determinate branches borne in whorls on nearly every cell of the main axis; (2) one or a few broad hairs originating near the base of the determinate branch system; (3) a well-defined group of meristematic cells at the base of the hair; and (4) extensive rhizoidal cortication in the lower portions of the plants and at the base of the main branches. Draparnaldiopsis simplex Jao is transferred to the genus Draparnaldia and renamed Draparnaldia jaoi nom. nov.