Competition and synergistic mechanisms of species in Phyllostachys edulis-Alsophila spinulosa association based on niche theory.

We examined the niche characteristics and interspecific covariant relationship of main species in Phyllostachys edulis-Alsophila spinulosa association in Chishui A. spinulosa National Nature Reserve under P. edulis disturbance condition, and analyzed the mechanism of competition and coexistence across different species. The results showed that there were 67 species from 53 genera and 40 families in the association. The importance values, Shannon niche breadth index (BS), and Levins niche breadth index (BL) of P. edulis were the largest, indicating its absolute dominant status in association. The importance value and BL of A. spinulosa ranked the second, while BS was the third. There were 190 pairs of 20 main species. The niche overlap between P. edulis and A. spinulosa was the largest, with niche overlap value of 0.64. 71.6% of species pairs had niche overlap of less than 0.2, indicating low niche overlap and high degree of niche differentiation among species. The overall association of main species in association was significantly positive, and the community was relatively stable. The correlation among the main species was not significant, the linkage was not strong, and the species were independent from each other. P. edulis showed significant positive correlation with A. spinulosa, Brassaiopsis glomerulata, Ficus virens, and Mallotus barbatus, while P. edulis showed significant negative correlation with Mallotus philippensis, Cinnamomum glanduliferum, and Machilus gamblei. Niche difference and fitness between P. edulis and natives affected the coexistence and competition among species. Controlling the expansion of P. edulis and limiting the size of species with negative correlation with A. spinulosa could create a favorable living environment for A. spinulosa.

The weathering process of carbonatite: weathering time.

Soil formation by rock weathering is driven by a combination of parent material, climate, organisms, topography, and time. Among these soil-forming factors, time plays a pivotal role in the weathering of carbonatite but it is a challenging factor to study quantitatively. A method for determining the weathering duration of carbonatite based on its weathering characteristics over a century-scale time period has not been clearly established. In this study, we selected abandoned carbonatite tombstones commonly found in the karst region of southwest China for investigation, using the date when the tombstones were erected as the onset of weathering. Chemical weathering indices were used to evaluate the weathering degree of different oxide contents produced by the carbonatite weathering process. In order to explore the weathering characteristics over time, the relationship between weathering duration and weathering degree was established. The results showed the following: (1) magnesium (Mg), aluminum (Al), silicon (Si), iron (Fe), titanium (Ti) are gradually enriched in the carbonatite regolith, and calcium (Ca) is gradually reduced. (2) The chemical indices of alteration (CIA), leaching coefficient (Lc), alumina-to-calcium ratio (AC) and mobiles index (Imob) can be successfully used for evaluation of the weathering degree of the carbonatite in different weathering time periods. (3) During the weathering of carbonatite, the weathering rate is a logarithmic function of time. Our research shows that over a period of more than 100 years of weathering, the carbonatite weathering process is characterized by fast weathering rates and low weathering degree in the early stages, but slow weathering rates in the later stages.

Nutrient availability and acid erosion determine the early colonization of limestone by lithobiontic microorganisms.

Introduction: Microorganisms, including the pioneer microorganisms that play a role in the early colonization of rock, are extremely important biological factors in rock deterioration. The interaction of microorganisms with limestone leads to biodeterioration, accelerates soil formation, and plays an important role in the restoration of degraded ecosystems that cannot be ignored. However, the process of microbial colonization of sterile limestone in the early stages of ecological succession is unclear, as are the factors that affect the colonization. Acid erosion (both organic and inorganic), nutrient availability, and water availability are thought to be key factors affecting the colonization of lithobiontic microorganisms. Methods: In this study, organic acid (Oa), inorganic acid (Ia), inorganic acid + nutrient solution (Ia + Nut), nutrient solution (Nut), and rain shade (RS) treatments were applied to sterilized limestone, and the interaction between microorganisms and limestone was investigated using high-throughput sequencing techniques to assess the microorganisms on the limestone after 60 days of natural placement. Results: The results were as follows: (1) The abundance of fungi was higher than that of bacteria in the early colonization of limestone, and the dominant bacterial phyla were Proteobacteria, Bacteroidota, and Actinobacteriota, while the dominant fungal phyla were Ascomycota, Basidiomycota, and Chytridiomycota. (2) Acid erosion and nutrient availability shaped different microbial communities in different ways, with bacteria being more sensitive to the environmental stresses than fungi, and the higher the acidity (Ia and Oa)/nutrient concentration, the greater the differences in microbial communities compared to the control (based on principal coordinate analysis). (3) Fungal communities were highly resistant to environmental stress and competitive, while bacterial communities were highly resilient to environmental stress and stable. Discussion: In conclusion, our results indicate that limestone exhibits high bioreceptivity and can be rapidly colonized by microorganisms within 60 days in its natural environment, and both nutrient availability and acid erosion of limestone are important determinants of early microbial colonization.

The diversity of resident passerine bird in the East Yunnan-Kweichow Plateau is closely related to plant species richness, vertical altitude difference and habitat area.

East Yunnan-Kweichow Plateau is rich in biodiversity in China. Complex geographical and climatic conditions and rich bird resources made this area an ideal system for studying the spatial distribution mechanism and influencing factors of birds, which were still unknown. Bird community data from 37 sites in this region were collected, including 505 bird species and 164 species of resident passerine bird, were extracted for analysis. The taxonomic diversity, phylogenetic diversity, functional diversity (FD), and community structure index were calculated. Ordinary least square (OLS), spatial autoregressive models (SAR), and structural equation model (SEM) were used to explore the relationship between bird diversity index and environmental factors which were used to describe the habitat conditions of birds. Results indicated that species richness (SR), phylogenetic diversity (PD), and FD have similar distribution patterns and are mainly affected by vascular plant species richness, habitat area, and vertical altitude difference. The phylogenetic and functional structure of bird community changed in both longitude and latitude direction, and the phylogenetic structure of community was dispersed in the west and clustered in the east, significantly related to habitat area, and vertical altitude difference, the functional structure was dispersed in all sites, significantly related to average annual precipitation. The community in the west and south of the East Yunnan-Kweichow Plateau is mainly driven by interspecific competitive, while the process in the east and north is mainly driven by environmental filtration. Distribution pattern of bird diversity was caused by the comprehensive action of various habitat factors which were mainly related to food availability and habitat heterogeneity. For maintaining the living space of birds, the protection of urban parks, wetland parks, campuses, and other urban green spaces is as important as national and provincial nature reserves. Revealing the construction mechanism and main influencing factors of bird communities in different areas is conducive to targeted protection work.

Litter eco-hydrological function characteristics of three typical plant communities in the area of Karst peak-cluster depressions from Guizhou, China.

Litter is an important component of forest ecosystems and plays an important eco-hydrological function. Many studies have been carried out on litter at present, but less research has been carried out on the eco-hydrological service functions of litter in different plant communities in Karst, especially in the area of Karst peak-cluster depressions in southwest China. To reveal the characteristics of the hydrological function of the litter layer of the plant community in the area of Karst peak-cluster depressions around FAST (Five-hundred-meter Aperture Spherical Radio Telescope), three typical plant community litter layers of the broad-leaved forest, coniferous forest, and shrub were selected as research objects, and the hydrological function of the litter layer of different plant community types was studied using the immersion method. The results indicated: 1) The litter layer of the broad-leaved forest plant community has the strongest function of intercepting and regulating precipitation (Mlmax = 24.17±0.33 t/ha, Msv = 19.93±0.21 t/ha), and its hydrological service function is the best. 2) The higher the decomposition degree of litter, the stronger the interception function. 3) The fitted equations for both the litter water-absorption capacity (Qct) and time (t) for plant communities were Qct = b + alnt, and the fitted equations for both the litter water-release capacity (Qst) and time (t) were Qst = a t b. 4) The fitted equations for both the water absorption and release rates (vc and vs) and time (t) of the litter were v = a t -b. The water absorption rates of litter were the fastest within 5 min (15529.01~22634.43 g/kg·h), with the greatest interception and storage function for short-term rainfall.

Change in composition and potential functional genes of microbial communities on carbonatite rinds with different weathering times.

Organisms and time are important factors for rock weathering to form soils. However, weathering time is usually difficult to quantitatively study, and the potential microorganisms involved in rock weathering are difficult to identify qualitatively. Currently, there is no clear conclusion on how ecological strategies of carbonatite weathering rind microorganisms change with weathering time, and how the microbial composition and functional genes involved in element cycling change over two century-scale weathering time. In this study, we selected abandoned carbonate tombstones as the subject and used the date when the tombstones were erected by humans as the onset of weathering. Using metagenome sequencing methods, we investigated the trends in the composition of fungal, bacterial and archaeal communities of carbonate weathering rind and related elemental cycle functional genes during a weathering time of 19 to 213 years. The results showed that: (1) with the increase in weathering time, at the phylum level, microbial taxa gradually shifted from r-strategists (faster turnover rates, higher mortality rates, higher reproduction, lower competition rate) to K-strategists (slower turnover rates, lower mortality rates, lower reproduction, higher competition rate), which correspondingly increased the abundance of functional genes related to C and N cycles. (2) The properties of the parent rock layer determines the colonization and distribution of weathering rind microorganisms (especially prokaryotic microorganisms) and the corresponding functional gene abundance. Our study provides new insights into the weathering process of carbonate rocks.

Abundance and characteristics of sediment-bound magnetic minerals and trace elements in karst ditch wetland: A case study from Guizhou Province, China.

This study investigated sediment-bound magnetic properties and selected trace elements level in the karst ditch wetland, Caohai National Nature Reserve, Guizhou Province, China. Sediment-bound magnetic signals were quantified using low-frequency mass magnetic susceptibility (χLF), anhysteretic remanent magnetization susceptibility (χARM), saturation isothermal remanent magnetization (SIRM), and percentage frequency-dependent susceptibility (χfd%). Concentrations of Cd, Cr, Sb and Zn were determined using inductively coupled plasma mass spectrometry. Sediment χLF, χARM, SIRM, and χfd% were higher than those of bedrocks and mainly altered by the pedogenic processes. The estimated χfd% ranged from 6.15 % to 14.62 % and reflected the magnetic grain sizes were largely concentrated in the range of superparamagnetic particles. The elevated concentrations of sediment-bound Cd, Cr, Sb, and Zn supported the significant contribution of the anthropogenic sources in the karst ditch wetlands. The weak relationship between magnetic signals and selected trace elements (p < 0.05) suggested the occurrence of few sediment-bound iron-containing minerals associated with selected trace elements. These results indicated that a minor contribution of anthropogenic sources of selected trace elements to the elevated sediment magnetic signals in the karst ditch wetlands.

Modification of nanoscale polymeric adsorbent for the preparative separation and purification of tacrolimus from fermentation broth of Streptomyces tsukubaensis.

Tacrolimus is an important immunosuppressant produced by microbial fermentation. In this study, a modified nanoscale polymeric adsorbent, Ag+-exchanged resin, was prepared and studied for the preparative separation and purification of tacrolimus from fermentation broth of Streptomyces tsukubaensis. The performance and absorption characteristics of the modified nanoscale polymeric adsorbent namely Ag-NPS was evaluated. Notably, Ag-NPS resin displayed the pronounced separation capacities for tacrolimus and its equilibrium adsorption data was well-fitted to the Langmuir isotherm. Moreover, the dynamic adsorption and desorption tests was carried out to obtain the operational parameters for further purification of tacrolimus. Finally, tacrolimus and the two major impurities, ascomycin and dihydrotacrolimus, were separated well in the scale-up purification process. The purity and recovery of tacrolimus was recorded to be 99.12±0.25% and 90.41±2.05%. In conclusion, this method displayed a high potential for separation and purification of tacrolimus and other unsaturated bioactive compounds in high yield from the fermentation broth.

Assessment of some trace elements accumulation in Karst lake sediment and Procambarus clarkii, in Guizhou province, China.

Lake wetland quality has decreased with the elevated concentrations of some trace elements. The consumption of crayfish in the trace elements concentrated lake wetland can be a hazard for the waterbirds and human health. Thus, the bioaccumulations of Cd, Ni, Pb and Zn in sediments and abdominal muscles of Procambarus clarkii in Caohai lake wetland, China were quantified. Sediment-bound Cd, Ni, Pb and Zn were remarkably elevated compared to the parent rock, while 64.71-94.12% of adverse effect index in sediment-bound Cd, Ni, Pb and Zn were > 1. Abdominal muscle-bound Cd, Pb and Zn in several samples were all above the maximum permissible limits. Pb, Zn and Ni in abdominal muscles were significantly linked with those in sediments (R2 =0.60-0.89, p < 0.01) and lake sediment might be the important feed sources of P. clarkii. Target hazard quotients of Cd, Ni, Pb and Zn at the 95th percentile was all below the benchmark, normal consumption of the abdominal muscle of P. clarkii posed low or no probabilistic health risk to the Grus nigricollis and local inhabitants.

The characteristics of habitat, functional traits and medicinal components of Eucommia ulmoides from Guizhou.

To find out the genuine characteristics of Eucommia ulmoides produced in Guizhou.The habitat, functional characters and the content of medicinal components of Eucommia ulmoides in Guizhou were studied by using the method of sample survey combined with typical survey, related laboratory experiments and quantitative analysis. The results showed that the yield of Eucommia ulmoides plantation in Guizhou was divided into low altitude, low middle and high temperature rain slope latitude mixing, short sunshine hours type(A type), medium altitude, low longitude and latitude, high temperature rain, positive oblique steep slope, medium sunshine hours type (B type), middle altitude, low longitude and latitude, moderate high temperature rain, shady side and sunny side have gentle deflection steep slope, medium sunshine hours type (C type), High altitude, low longitude and latitude, low temperature moderate rain, positive gentle slope, long sunshine hours type (D type); Different types of Eucommia ulmoides plantation, Different habitat quality, B type is intensity karst rocky desertification habitat, A type is potential karst rocky desertification habitat, the C and D types are light and moderate rocky desertification areas, respectively, the species diversity of shrub layer in Eucommia ulmoides plantation was higher in D type and B type, A type and C type followed; There was no significant difference in root carbon content and leaf nitrogen content in 4 types of Eucommia ulmoides plantation, Among the four types of A, B, C, D, there were significant or extremely significant differences in other indexes of plant functional traits; Both genipinic acid and aucubin had the highest content of root bark, followed by trunk bark and lowest leaves, Chlorogenic acid is the opposite, The content of geniposide was higher in trunk bark and lower in root bark and leaves; Genipinic acid is higher in D type, Aucubin is higher in A and D type, Chlorogenic acid has higher leaves content in B type, Geniposide was the highest in trunk bark of D type; The element enrichment coefficient K and Mn leaves are the largest, the largest in trunk bark is Ca and Zn, Fe root bark is the largest; Effects of soil potassium, phosphorus, pH value and bulk weight on the functional traits of Eucommia ulmoides were significant. The contents of medicinal components in root bark, trunk bark, and leaves was influenced by species diversity of shrub layer, The contents of geniposide in root bark, aucubin in root bark and trunk bark, genipinic acid in bark and chlorogenic acid in leaves were particularly affected by soil physical and chemical indexes and metal element contents, The functional traits of Eucommia ulmoides can affect the content of medicinal components in root bark, trunk bark, and leaves, Especially on the root bark, trunk bark, and leaves in the content of aucubin content; The content of medicinal components of Eucommia ulmoides was high and stable. The above research results have important theoretical reference significance for the cultivation of Eucommia ulmoides and the cultivation of target medicinal components and the comprehensive exploitation and utilization of resources.

A comparative study of sediment-bound trace elements and iron-bearing minerals in S. alterniflora and mudflat regions.

Elevated sediment-bound trace elements and iron-bearing minerals in intertidal habitats have been drawing more attention, but there is rarely a comparative study assessing these features between halophyte plants habitat and mudflats. In this paper, sediment samples were collected in S. alterniflora and the corresponding mudflat at 7 typical intertidal habitats (Chongming, Xiapu, Yueqing, Yunxiao, Zhanjiang, Beihai, and Zhuhai) from north to south of China, respectively. Trace element concentrations, including arsenic (As), mercury (Hg), cadmium (Cd), antimony (Sb) and scandium (Sc), and magnetic characteristics were determined. Variations in sediment-bound As, Hg, Cd, Sb were associated with S. alterniflora. Accumulations of sediment-bound As, Hg, Sb, Cd and Sc in S. alterniflora in Beihai were much higher than those in the mudflat. Concentration of sediment-bound As, Hg, Sb, Cd and Sc in S. alterniflora and mudflat were comparable in Yueqing, Xiapu, Yunxiao and Zhanjiang, respectively. Variations in low-frequency susceptibility, susceptibility of anhysteretic remanence magnetization, saturation isothermal remanence magnetization and frequency dependent susceptibility can explain the site-dependent accumulation of magnetic minerals in intertidal habitats. S. alterniflora tend to deplete sediment magnetic concentration and enhance sediment-bound As, Hg, and Sb concentration. The results of our study further revealed the coexistence of trace elements and magnetic minerals between the sampling sites and vegetative in intertidal habitats.

Improvement of tacrolimus production in Streptomyces tsukubaensis by mutagenesis and optimization of fermentation medium using Plackett-Burman design combined with response surface methodology.

OBJECTIVE: This study was conducted to enhance the production of tacrolimus in Streptomyces tsukubaensis by strain mutagenesis and optimization of the fermentation medium. RESULTS: A high tacrolimus producing strain S. tsukubaensis FIM-16-06 was obtained by ultraviolet mutagenesis coupled with atmospheric and room temperature plasma mutagenesis.Then, nine variables were screened using Plackett-Burman experimental design, in which soluble starch, peptone and Tween 80 showed significantly affected tacrolimus production. Further studies were carried out employing central composite design to elucidate the mutual interaction between the variables and to work out optimal fermentation medium composition for tacrolimus production. The optimum fermentation medium was found to contain 61.61 g/L of soluble starch, 20.61 g/L of peptone and 30.79 g/L of Tween 80. In the optimized medium, the production of tacrolimus reached 1293 mg/L in shake-flask culture, and reached 1522 mg/L while the scaled-up fermentation was conducted in a 1000 L fermenter, which was about 3.7 times higher than that in the original medium. CONCLUSIONS: Combining compound mutation with rational medium optimization is an effective approach for improving tacrolimus production, and the optimized fermentation medium could be efficiently used for industrial production.

Identification of gntK, a gene required for the methylation of purpurosamine C-6' in gentamicin biosynthesis.

Gentamicin and sisomicin are two different aminoglycoside antibiotics. The comparison of their chemical structure and biosynthetic gene clusters, coupled with bioinformatic analysis, suggested that the gntK gene would be associated with methylation. The gntK gene fragment in M. purpurea G1008 was inactivated by genetic engineering and its mutant strain M. purpurea GK1101 (ΔgntK) was screened. The metabolites of G1008 and GK1101 was analyzed by HPLC-MS, which revealed that GK1101 no longer produced gentamicin C(1) or C(2), while mainly synthesizing gentamicin C(1a), and the production of C(1a) increased significantly. This indicated that the metabolic flow for the gentamicin C(1) and C(2) biosynthesis was blocked by disrupting the gntK gene, which substantiated that the gntK gene encoded the enzyme that catalyzes the methylation of purpurosamine C-6'. The mutant GK1101 has good prospects for industrial application. In addition, our study provides information that can be used to clarify the function of a single gene and simplify the targeted genetic breeding of important pharmaceutical microorganisms.