Search

Just as in deep-water sedimentary environments, productive source rocks can be developed in an evaporitic platform, where claystones are interbedded with evaporites and carbonates. However, the impact of the paleoenvironment on the organic matter enrichment of shallow water source rocks in an evaporite series has not been well explored. In this study, two wells in the central uplift of the Tarim Basin were systematically sampled and analyzed for a basic geochemical study, including major elements, trace elements, and total organic carbon (TOC), to understand the relationship between TOC and the paleoenvironmental parameters, such as paleosalinity, redox, paleoclimate, paleo-seawater depth, and paleoproductivity. The results show that the Lower–Middle Cambrian mainly developed in a fluctuating salinity, weak anoxic to anoxic, continuous dry and hot, and proper shallow water environment. The interfingering section of evaporites, carbonates, and claystones of the Awatag Fm. have higher paleoproductivity and higher enrichment of organic matter. Paleosalinity, redox, paleoclimate, paleo-seawater depth, and paleoproductivity jointly control the organic matter enrichment of shallow water source rocks in the evaporite series. The degree of enrichment of organic matter in shallow water source rocks first increases and then decreases with the increase in paleosalinity. All the samples with high content of organic matter come from the shallower environment of the Awatag Fm.

Tight oil sandstones have complex pore structure due to multiple pore types and multiscale pore size ranging from several nanometers to dozens of microns. In this study, petrophyiscal properties of tight oil sandstones were quantified based on microscale X-ray computed tomography (μXCT) imaging techniques. The pore types in gray scale images were identified; porosity, pore size distribution (PSD), and pore connectivity were analyzed from segmented image stacks; and their permeability was calculated by representative elementary volume (REV) scale lattice Boltzmann method (LBM). Three types of pores including residual interparticle pores, grain dissolution pores and micro fractures were identified. A multi-threshold segmentation algorithm was applied to segment the image stacks into three constituents, namely, pore, matrix, and clay. The calculated volumetric fraction of the pore constituent from the segmented image stacks was smaller than experimental porosity, because a certain amount of porosity was also contributed by clay constituent. The PSD of the samples was found to be unimodal in the range of 3–69 μm, with the peak at around 10–15 μm. The clay constituent led to the increase in the overall connectivity of the images stacks, indicating that clays bridged the isolated pores. By assigning appropriate porosity and permeability to the clay constituent, calculated permeability of the samples using REV scale LBM well matched the experimental data. This study provides new insight into characterization of pore structure of tight oil sandstones by μXCT technique.

The gut microbiota is closely related to shrimp growth and health. However, the response patterns of gut bacterial communities to environmental stresses (such as cold) in distinct shrimp strains and their association with host status are still unclear. In this study, stress tolerance and its potential association with the gut microbiota in two white shrimp Litopenaeus vannamei strains (ZT and PM) were investigated using 16S rRNA gene amplicon sequencing. The stable body weight of PM relative to the obvious weight loss of ZT after both were subjected to cold stress (at the adult life stage) suggests that PM possess stronger tolerance to cold stress. Meanwhile, the α-diversity indices of PM gut bacteria were significantly higher than those of ZT, and the bacterial community structure in the PM gut was more stable as well. Furthermore, cold stress led to domination of the bacterial composition in the ZT gut by the families Erysipelotrichaceae, Mycoplasmataceae, and Vibrionaceae, which have potential pathogenic members. On the other hand, the relative abundances of 18 discriminatory families, represented by Rhodobacteraceae (33.8%), in the PM gut were significantly higher than those in the ZT gut, suggesting that distinct gut bacterial assemblages may reflect the stress resistance potential of shrimp. The taxonomic signature of gut microbiota of the cold-resistant strain could be a guidance for isolation of novel probiotics from bacterial groups such as Rhodobacteraceae, which could be potentially applied to reduce the influence of cold stress in white shrimp.

Wulong geese are renowned for their egg-laying and reproductive abilities. This work investigated the potential of using body size traits in the selection and breeding of high-yielding Wulong geese. A total of forty 479day-old female geese (high-yielding geese, n = 20; low-yielding geese, n = 20) were selected to evaluate the relationship between body weight, body size trait indicators, serum reproductive hormones, and biochemical indicators. The results showed that serum estradiol (E2), glucose (GLU), and triglyceride (TG) concentrations, together with pubic spacing and abdominal circumference were significantly higher in high-yielding geese (P < 0.01), whereas the opposite was true for neck circumference, neck length, and tibial circumference. In addition, the serum testosterone (T) concentration and body weight were higher in high-yielding geese (P < 0.05). Neck circumference and neck length were negatively correlated with E2 and TG (P < 0.01); while pubic spacing and abdominal circumference were positively correlated with E2, GLU, and TG (P < 0.01), the highest correlation coefficient was 0.777 between TG and pubic spacing; T was also strongly associated with neck circumference (P < 0.01). In conclusion, high-yielding Wulong geese can be selected through neck circumference, neck length, pubic spacing, and abdominal circumference.

Understanding how species interaction and assembly processes structure the abundant and rare bacterial biospheres in soils is crucial for predicting how biodiversity influences ecosystem functioning. Here, we profiled the bacterial communities across a salt marsh ecosystem gradient to investigate the co-occurrence patterns across taxa and the relative influence of ecological processes mediating the assembly of the abundant and rare biospheres in soil. Our results revealed abundant taxa to be ubiquitous across all sites, whereas the distributions of the rare taxa were relatively more site specific. The α-diversity indices and β-diversity of rare subcommunities were significantly higher than those of the abundant subcommunities. Besides, both the taxonomic and functional composition of soil bacterial communities differed significantly between the two biospheres. Furthermore, the influence of stochasticity differed in each subcommunity. In particular, stochastic processes were relatively more important in constraining the assembly of rare taxa. Co-occurrence network analysis revealed that a few abundant taxa occupy central nodes within the networks, possibly indicating crucial roles as keystone taxa. Collectively, these findings suggest that abundant and rare bacterial biospheres have distinct distributions underpinned by a dynamic interplay of ecological processes and taxon co-occurrence patterns. IMPORTANCE Estuarine salt marshes are highly productive ecosystems subjected to regular disturbances by hydrodynamic exchange. However, little is known about how distinct assembly processes and co-occurrence of taxa influence the structure of the abundant and rare bacterial biospheres in these soil systems. This study aims at unravelling these intricacies by studying a typical estuarine salt marsh located in Hangzhou Bay, China. Our study provides important pieces of evidence on the diverse distribution of rare and abundant bacterial biospheres. We show that a few abundant taxa are central nodes in species co-occurrence, potentially playing important roles as keystone species in the system. In addition, we highlight a dynamic interplay of assembly processes structuring these two subcommunities.

Marine planktonic bacteria and archaea commonly exhibit pronounced seasonal succession in community composition. But the existence of seasonality in their assembly processes and between-domain differences in underlying mechanism are largely unassessed. Using a high-coverage sampling strategy (including single sample for each station during four cruises in different seasons), 16S rRNA gene sequencing, and null models, we investigated seasonal patterns in the processes governing spatial turnover of bacteria and archaea in surface coastal waters across a sampling grid over ~300 km in the East China Sea. We found that archaea only bloomed in prokaryotic communities during autumn and winter cruises. Seasonality mostly overwhelmed spatial variability in the compositions of both domains. Bacterial and archaeal communities were dominantly governed by deterministic and stochastic assembly processes, respectively, in autumn cruise, probably due to the differences in niche breadths (bacteria archaea) and relative abundance (bacteria archaea). Stochasticity dominated assembly mechanisms of both domains but was driven by distinct processes in winter cruise. Determinism-dominated assembly mechanisms of bacteria rebounded in spring and summer cruises, reflecting seasonal variability in bacterial community assembly. This could be attributed to seasonal changes in bacterial niche breadths and habitat heterogeneity across the study area. There were seasonal changes in environmental factors mediating the determinism-stochasticity balance of bacterial community assembly, holding a probability of the existence of unmeasured mediators. Our results suggest contrasting assembly mechanisms of bacteria and archaea in terms of determinism-vs.-stochasticity pattern and its seasonality, highlighting the importance of seasonal perspective on microbial community assembly in marine ecosystems.

Additional file 2: Figure S1. Experimental design and sampling schedules. Figure S2. Dynamics of bacterial α-diversity and evenness indices of shrimp larvae and water across developmental stages. Figure S3. Linear discriminant analysis taxonomic cladogram showing discriminatory taxa at each developmental stage of shrimp larvae. Figure S4. Dynamics of bacterial community similarity among larvae samples and between larvae and water samples. Figure S5. The relationship between larval shrimp and water bacterial communities. Figure S6. Heatmaps showing the predicted function potentials of larval shrimp bacterial communities across the developmental stages.

Additional file 1: Table S1. Pairwise similarity test of bacterial communities between larval shrimp developmental stages. Table S2. Analysis of Similarity (ANOSIM) testing the differences between larval shrimp and rearing water bacterial communities.

Anthropogenic nutrient discharge poses widespread threats to coastal ecosystems and has increased environmental gradients from coast to sea. Bacterioplankton play crucial roles in coastal biogeochemical cycling, and a variety of factors affect bacterial community diversity and structure. We used 16S rRNA gene pyrosequencing to investigate the spatial variation in bacterial community composition (BCC) across five sites on a coast-offshore gradient in the East China Sea. Overall, bacterial alpha-diversity did not differ across sites, except that richness and phylogenetic diversity were lower in the offshore sites, and the highest alpha-diversity was found in the most landward site, with Chl-a being the main factor. BCCs generally clustered into coastal and offshore groups. Chl-a explained 12.3% of the variation in BCCs, more than that explained by either the physicochemical (5.7%) or spatial (8.5%) variables. Nutrients (particularly nitrate and phosphate), along with phytoplankton abundance, were more important than other physicochemical factors, co-explaining 20.0% of the variation in BCCs. Additionally, a series of discriminant families (primarily affiliated with Gammaproteobacteria and Alphaproteobacteria), whose relative abundances correlated with Chl-a, DIN, and phosphate concentrations, were identified, implying their potential to indicate phytoplankton blooms and nutrient enrichment in this marine ecosystem. This study provides insight into bacterioplankton response patterns along a coast-offshore gradient, with phytoplankton abundance increasing in the offshore sites. Time-series sampling across multiple transects should be performed to determine the seasonal and spatial patterns in bacterial diversity and community structure along this gradient.

Carbonate karst is one of the research highlights in the field of carbonate reservoir geology. High porosity zones can develop in carbonate rocks which are modified by the karst. However, the carbonate porosity development and its evolution process in a polyphase paleokarst are rarely reported in the geological record. Here, the paper focuses on this point from the Precambrian Upper Sinian carbonate in the north Tarim basin, northwest China. Five outcrops and two wells reveal that the karstic porosity development of Upper Sinian carbonate was petrography-controlled of microbial dolostone and grain dolostone. The karstic porosities were in relation to three paleokarst phases: (1) eogenetic karst during depositional environment, (2) telogenetic karst at the end of late Sinian, and (3) hydrothermal karst in the early Permian. Eogenetic karst was related to frequent and short sea-level fluctuation, and was characterized by selective dissolution of intragranular dissolution porosity, moldic porosity, bird’s eye porosity, and intergranular dissolution porosity. Telogenetic karst was related to tectonic uplift, and was characteristic of non-selective dissolution of vugs and cavities with karst intensity increasing upward. Hydrothermal karst was related to geothermal events, and was featured by highly solution-enlarged porosities which mainly overprinted earlier telogenetic and eogenetic karst porosities. The suggested paleokarst model, combined with the related karstic porosity evolution process, will perfectly reveal its porosity development.

Coastal ecosystems are receiving elevated loads of nitrogen (N) from anthropogenic sources. Understanding how excessive N loading affects bacterioplankton communities is critical to predict the biodiversity of marine ecosystems under conditions of eutrophic disturbance. In this study, oligotrophic coastal water microcosms were perturbed with nitrate in two loading modes: 1) one-off loading at the beginning of the incubation period; and 2) periodic loading every two days for 16 days. Turnover in the bacterioplankton community was investigated by 16S rDNA gene amplicon sequencing. The alpha diversity of the bacterioplankton community showed great temporal variability and similar responses to the different treatments. Bacterioplankton community composition was influenced remarkably by time and N loading mode. The effects of N loading on bacterioplankton community structure showed obvious temporal variation, probably because of the great temporal variation in environmental parameters. This study provides insights into the effects of N pollution in anthropogenically perturbed marine environments.

Phytoplankton bloom has imposed ecological concerns worldwide; however, few studies have been focused on the successional trajectories of bacterioplankton community over a complete phytoplankton bloom cycle. Using 16S pyrosequencing, we investigated how the coastal bacterioplankton community compositions (BCCs) respond to a phytoplankton bloom in the Xiangshan Bay, East China Sea. The results showed that BCCs were significantly different among the pre-bloom, bloom, and after-bloom stages, with the lowest bacterial diversity at the bloom phase. The BCCs at the short-term after-bloom phase showed a rapid but incomplete recovery to the pre-bloom phase, evidenced by 69.8% similarity between pre-bloom and after-bloom communities. This recovery was parallel with the dynamics of the operational taxonomic units (OTUs) affiliated with Actinobacteria, Bacteroidetes, Cyanobacteria, Alphaproteobacteria and Gammaproteobacteria, whose abundance enriched when bloom occur, and decreased after-bloom, and vice versa. Collectively, the results showed that the BCCs were sensitive to algal-induced disturbances, but could recover to a certain extent after bloom. In addition, OTUs which enriched or decreased during this process are closely associated with this temporal pattern, thus holding the potential to evaluate and indicate the succession stage of phytoplankton bloom.

Bacterial communities play essential roles in estuarine marsh ecosystems, but the interplay of ecological processes underlying their community assembly is poorly understood. Here, we studied the sediment bacterial communities along a linear gradient extending from the water-land junction toward a high marsh, using 16S rRNA gene amplicon sequencing. Bacterial community compositions differed significantly between sediment transects. Physicochemical properties, particularly sediment nutrient levels (i.e., total nitrogen [TN] and available phosphorus [AP]), as well as sediment physical structure and pH (P

Shiga toxin-producing Escherichia coli (E. coli) O157:H7 is recognized as a hazardous microorganism in the environment. Its longer survival might contribute to higher contamination risk. In this study, E. coli O157:H7 survival in estuarine sediments collected from south Hangzhou Bay was investigated. The survival time of E. coli O157:H7 in estuarine sediments increased with the distance to the water-land junction. Sediment pH was the most important factor in regulating E. coli O157:H7 survival in estuarine sediments. In addition, sediment nutrients and texture also played significant roles in the survival of E. coli O157:H7 in the sediments. On the other hand, bacterial diversity as determined by the alpha-diversity index had no significant effect on E. coli O157:H7 survival. However, specific families of bacteria were closely associated with E. coli O157:H7 survival in the sediments. Remarkably, some potential bacterial groups, e.g., the Desulfobacteraceae, Desulfobulbaceae and Desulfarculaceae families, which are mainly involved in the sulfur cycle, showed significant negative correlation with the E. coli O157:H7 survival in the sediments. On the whole, abiotic factors showed greater effects on E. coli O157:H7 survival in the test sediments than the bacterial community. Our findings provide a comprehensive understanding of E. coli O157:H7 survival and regulatory factors in estuarine sediments, establishing foundation for the prevention of pathogen contamination.

Among hand trauma, nail bed is the most involved tissue in hospital emergency departments, resulting in the loss of nail plate, which leads to a disturbance of hand grasp function, long-lasting digit tip pain, hyperpathia, and disesthesia. Treatment of nail bed defects is a significant clinical challenge due to the lack of uniform nail bed thickness and distinct regenerative ability. In this study, it is shown that the extracellular matrix of decellularized nail bed scaffolds can play an important role in inducing bone mesenchymal stem cells to differentiate into nail epithelial cells. Using decellularized nail bed scaffolds combined with bone mesenchymal stem cells, it is revealed that the engineered nail bed can promote nude mouse nail plate regeneration ectopically. The natural extracellular matrix of decellularized nail bed scaffolds can serve as a 3D structural template for bone mesenchymal stem cell differentiation into nail-associated cells, initiating the nail plate regeneration. These results not only provide a proof-of-principle for the generation of transplantable nail grafts based on decellularized nail bed scaffolds derived from clinically wasted amputated fingers but also provide important considerations for clinical treatment for digit tip trauma.

The common shrimp disease, acute hepatopancreatic necrosis disease (AHPND), has caused extensive damage to the shrimp farming industry due to its rapid spread and high mortality rates. However, the alterations in gastrointestinal microbiota (GM) ecosystem in subadult shrimps (Litopenaeus vannamei) with AHPND occurrence are still unclear. This study identified AHPND according to clinical symptoms and the existence of the toxin gene pirAVP, analyzed the microbiome dynamics of healthy and diseased subadult shrimps, and built an ecological model for quantitative evaluation of the GM imbalance. The results showed that the GM community diversity in diseased shrimps was significantly lower than that in healthy ones. The structural composition, dysbiosis-related indices, and assembly processes of the GM community were also evidently changed in diseased shrimps. The different operational taxonomic units (OTUs) in GM of diseased shrimps were mainly composed of Vibrio spp. with a relative abundance >90%, the majority of these were neutrally distributed in the neutral model of AHPND occurrence. Of 39 biomarkers for predicting AHPND occurrence, nine belonging to Vibrio were overrepresented in diseased shrimps, whereas biomarkers such as Rhodobacteraceae OTU3427, Candiadatus aysiosphaera OTU1041, KD4-96 OTU4963, and Rhodobacter OTU3366 were enhanced in healthy shrimps. Functional prediction showed that the gene abundances of the NOD receptor signaling pathway (p = .04), Vibrio infection (p

Microbial fermentation can increase the water-soluble protein (WSP) contents of soybean meal, but the microbial community compositions and its functions remain unclear during the fermentation of soybean meal. In this study, the soybean meal was naturally fermented and the dynamics of bacterial community structure were determined. The results showed that natural fermentation can significantly increase the WSP content and digestive enzyme activities of soybean meal. The bacterial diversity indexes of soybean meal were increased and the community structure was significantly changed after fermentation. The bacterial community composition mainly consisted of Pseudomonas before fermentation, but it was almost completely replaced by Bacillus after 24 h of fermentation. The key operational taxonomic unit (OTU) for fermentation was screened as OTU161 from Bacillus, and its candidate strain was isolated from the fermented soybean meal and identified as Bacillus amyloliquefaciens ZB. Bioaugmented inoculation of ZB significantly increased the WSP content by 110.0%, 47.2%, and 473.7%, respectively, after 24, 72, and 96 h of fermentation and digestive enzyme activities by 16.1–41.8% during 24–48 h of fermentation, and shorten the fermentation time, compared to natural fermentation.

Microplastics have emerged as a new anthropogenic substrate that can readily be colonized by microorganisms. Nevertheless, microbial community succession and assembly among different microplastics in nearshore mariculture cages remains poorly understood. Using an in situ incubation experiment, 16S rRNA gene amplicon sequencing, and the neutral model, we investigated the prokaryotic communities attached to polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP) in a mariculture cage in Xiangshan Harbor, China. The α-diversities and compositions of microplastic-attached prokaryotic communities were significantly distinct from free-living and small particle-attached communities in the surrounding water but relatively similar to the large particle-attached communities. Although a distinct prokaryotic community was developed on each type of microplastic, the communities on PE and PP more closely resembled each other. Furthermore, the prokaryotic community dissimilarity among all media (microplastics and water fractions) tended to decrease over time. Hydrocarbon-degrading bacteria Alcanivorax preferentially colonized PE, and the genus Vibrio with opportunistically pathogenic members has the potential to colonize PET. Additionally, neutral processes dominated the prokaryotic community assembly on PE and PP, while selection was more responsible for the prokaryotic assembly on PET. The assembly of Planctomycetaceae and Thaumarchaeota Marine Group I taxa on three microplastics were mainly governed by selection and neutral processes, respectively. Our study provides further understanding of microplastic-associated microbial ecology in mariculture environments.

Phosphorus (P), primarily as phosphate, is considered as a key trophic factor of eutrophication in coastal environments. Information on the response of bacterial community to excess phosphate loading in oligotrophic coastal water could provide insights into the micro-ecological effects on the expanding trend of nutrient-enrichment in coastal water. In this study, temporal dynamic of bacterioplankton community composition was investigated using 16S Illumina MiSeq sequencing technique in oligotrophic seawater microcosms manipulated with no perturbation (control) and a certain level of phosphate by two loading modes: 1) one-off loading at the beginning of incubation; and 2) periodic loadings every two days over a 16-day duration. The results showed that overall bacterial alpha-diversity temporally changed and achieved the lowest value in phosphate loading (P-loading) microcosms at day 8; phosphate-addition increased the Shannon index and Pielou's evenness compared with those of the control at day 16. Bacterioplankton community turnover across all the treatments showed a similar temporal pattern. P-loading significantly affected bacterioplankton community composition with negative correlations of Methylophilaceae and Flavobacteriaceae and positive correlation of Saprospiraceae. Periodic loading treatments demonstrated a greater effect on community variation than one-off loading treatments did. Moreover, excess P-loading accelerated the temporal succession of the bacterioplankton community composition. These results provide insights into the pattern of bacterioplankton community phylogenetically responding to excess P-loading in the manipulated oligotrophic coastal system.

Terminating harmful algal blooms by using algicidal agents is a strong disturbance event in marine environment, which has powerful structural influences on microbial ecosystems. But, the response of microbial ecosystem to algicidal agent is largely unknown. Here, we conducted Phaeocystis globosa microcosms to investigate the dynamics, assembly processes, and co-occurrence patterns of microbial communities in response to algicidal process induced by a highly efficient algicidal agent, prodigiosin, by using 16S rRNA gene amplicon sequencing. The α-diversity of microbial community showed no obvious changes during the algicidal process in P. globosa microcosm treated with prodigiosin (group PD). Rhodobacteraceae increased significantly (P 0.05) during algicidal process in PD, and this was mainly due to the lysis of P. globosa cells. Compared to the control group, the temporal turnover rates of common and rare taxa in PD were significantly higher because of the lysis of P. globosa induced by prodigiosin. Neutral processes mainly drove the assembly of microbial communities in all microcosms, even though the algicidal process induced by prodigiosin had no effect on the assembly processes. In addition, the time-decay relationship and co-occurrence network analysis indicate that rare taxa play important roles in maintaining microbial community stability in response to the algicidal process, rather than prodigiosin. These findings suggest that prodigiosin cannot affect the dynamics of microbial communities directly; however, future investigations into the function of microbial communities in response to prodigiosin remain imperative.

Seasonal succession in bacterioplankton is a common process in marine waters. However, seasonality in their spatial turnover is largely unknown. Here, we investigated spatial turnover of surface bacterioplankton along a nearshore-to-offshore gradient in the East China Sea across four seasons. Although seasonality overwhelmed spatial variability of bacterioplankton composition, we found significant spatial turnover of bacterioplankton along the gradient as well as overall seasonal consistency in biogeographic patterns (including distance&ndash, decay relationship and covariation of community composition with distance to shore) with subtle changes. Bacterioplankton assembly was consistently dominated by deterministic mechanisms across seasons, with changes in specific processes. We found overall seasonal consistency in abiotic factors (mainly salinity and nitrogen and phosphorus nutrients) shaping bacterioplankton composition, while phytoplankton showed a similar influence as abiotic factors only in spring. Although key taxa responsible for bacterioplankton spatial turnover showed certain season-specificity, seasonal switching between closely related taxa occurred within most dominant families. Moreover, many close relatives showed different responding patterns to the environmental gradients in different seasons, suggesting their differences in both seasonally climatic and spatially environmental preferences. Our results provide insights into seasonal consistency and variability in spatial turnover of bacterioplankton in terms of biogeographic patterns, ecological processes, and external and internal drivers.

Oyster (Crassostrea gigas) shell-loading in aquaculture systems can regulate water quality, a critical factor for Litopenaeus vannamei growth. However, the effects of oyster shell-loading on the bacterial community composition and their interactions during shrimp culture processes remain elusive. Here, 16S rRNA gene amplicon sequencing was used to investigate the dynamics and co-occurrence patterns of bacterial communities in L. vannamei culture systems loaded with oyster shells. The results indicated that oyster shell-loading significantly improved both shrimp survival and water quality. Oyster shell-loading was found to cause a significant increase in the relative abundance of Alphaproteobacteria (P

Biofloc technology (BFT) has been widely studied and applied in aquaculture, but the bacterial community compositions (BCCs) of bioflocs with different sizes and their associations with the shrimp gut microbiota remain unclear. In this study, bacterial communities of shrimp gut and the bioflocs with three different size-fractions (BS, 100 μm) were investigated by MiSeq sequencing technique. Significantly different bacterial communities were observed between the large (> 20 μm) and small ( 20 μm). A majority of these taxa were strongly correlated with shrimp health or water environmental parameters. However, some candidate pathogens (i.e., Vibrionaceae, Mycoplasmataceae and Pseudoalteromonadaceae) were overrepresented in small-sized bioflocs (

Commercial microbial agents (e.g., probiotics, microbial products, microorganism preparation et al.) have been widely applied for disease control in shrimp culture. However, the effect of these microbial agents (MA) on shrimp health is unstable and the underlying mechanism remains unclear. The effect of MA can probably be achieved by influencing the bacterial community of shrimp culture system. To test this hypothesis, we used 16S rRNA gene amplicon sequencing to investigate the dynamics of both planktonic and intestinal bacterial composition in shrimp culture ponds with or without commercial MA applied weekly. The results showed that MA application increased the temporal turnover rate of bacterioplankton community. Within 1 week, MA-treatment significantly drove bacterioplankton community composition to divert from that without MA-treatment at day 2 after MA application, but the deviation tended to vanish at days 4 and 7. At day 21, a significant difference was observed in shrimp intestinal bacterial community between two groups. The relative abundance of Rhodobacteraceae in shrimp intestine was significantly greater in the MA-treated group than that in the control. However, MA-treatment did not significantly improve the growth or survival ratio of shrimp. This study suggest that MA works in terms of accelerating bacterioplankton community turnover and shifting intestinal bacterial community, however, its effect on shrimp growth might vary greatly and might be improved by optimizing the method in activation and application and more investigation on the microbial ecological process of shrimp culture system is needed before we develop and apply probiotics more efficiently.

Marine Archaea are crucial in biogeochemical cycles, but their horizontal spatial variability, assembly processes, and microbial associations across complex coastal waters still lack characterizations at high coverage. Using a dense sampling strategy, we investigated horizontal variability in total archaeal, Thaumarchaeota Marine Group (MG) I, and Euryarchaeota MGII communities and associations of MGI/MGII with other microbes in surface waters with contrasting environmental characteristics across ~200 km by 16S rRNA gene amplicon sequencing. Total archaeal communities were extremely dominated by MGI and/or MGII (98.9% in average relative abundance). Niche partitioning between MGI and MGII or within each group was found across multiple environmental gradients. "Selection" was more important than "dispersal limitation" in governing biogeographic patterns of total archaeal, MGI, and MGII communities, and basic abiotic parameters (such as salinity) and inorganic/organic resources as a whole could be the main driver of "selection". While "homogenizing dispersal" also considerably governed their biogeography. MGI-Nitrospira assemblages were speculatively responsible for complete nitrification. MGI taxa commonly had negative correlations with members of Synechococcus but positive correlations with members of eukaryotic phytoplankton, suggesting that competition or synergy between MGI and phytoplankton depends on specific MGI-phytoplankton assemblages. MGII taxa showed common associations with presumed (photo)heterotrophs including members of SAR11, SAR86, SAR406, and Candidatus Actinomarina. This study sheds light on ecological processes and drivers shaping archaeal biogeography and many strong MGI/MGII-bacterial associations across complex subtropical coastal waters. Future efforts should be made on seasonality of archaeal biogeography and biological, environmental, or ecological mechanisms underlying these statistical microbial associations.

Harmful algal blooms (HABs) are serious ecological disasters in coastal areas, significantly influencing biogeochemical cycles driven by bacteria. The shifts in microbial communities during HABs have been widely investigated, but the assembly mechanisms of microbial communities during HABs are poorly understood. Here, using 16S rRNA gene amplicon sequencing, we analyzed the microbial communities during an early-spring diatom bloom, in order to investigate the dynamics of microbial assembly processes. Rhodobacteraceae, Flavobacteriaceae, and Microbacteriaceae were the main bacterial families during the bloom. The 30 most abundant operational taxonomic units (OTUs) segregated into 4 clusters according to specific bloom stages, exhibiting clear successional patterns during the bloom process. The succession of microbial communities correlated with changes in the dynamics of algal species. Based on the β-nearest taxon distance, we constructed a simulation model, which demonstrated that the assembly of microbial communities shifted from strong heterogenous selection in the early stage of the bloom to stochasticity in the middle stage and then to strong homogeneous selection in the late and after-bloom stages. These successions were driven mainly by chlorophyll a contents, which were affected mainly by Skeletonema costatum. Moreover, functional prediction of microbial communities showed that microbial metabolic functions were significantly related to nitrogen metabolism. In summary, our results clearly suggested a dominant role of determinacy in microbial community assembly in HABs and will facilitate deeper understanding of the ecological processes shaping microbial communities during the algal bloom process. IMPORTANCE Harmful algal blooms (HABs) significantly influence biogeochemical cycles driven by bacteria. The shifts in microbial communities during HABs have been studied intensively, but the assembly mechanisms of microbial communities during HABs are poorly understood, with limited investigation of the balance of deterministic and stochastic processes in shaping microbial communities in HABs. In this study, the dynamics and assembly of microbial communities in an early-spring diatom bloom process were investigated. Our data both confirm previously observed general microbial successional patterns and show new detailed mechanisms for microbial assembly in HABs. These results will facilitate deeper understanding of the ecological processes shaping microbial communities in HABs. In addition, predictions of metabolic potential in this study will facilitate understanding of the influence of HABs on nitrogen metabolism in marine environments.

Additional file 1: Table S1. The average body length and the weight of the shrimp under different health state across three sampling days. Figure S1. Rarefaction curves of individual shrimp samples. Rarefaction curves were assembled showing the number of OTUs, defined at the 97% sequence similarity cut-off, relative to the number of total sequences. The dashed vertical line indicates the number of sequences subsampled from each sample to calculate alpha diversity estimates. Figure S2. The alpha-diversity indices (Shannon index and number of observed species, per 26100 sequences of the shrimp gut samples under different health state across three sampling days. HI: healthy gut; DI: diseased gut. Significant differences were indicated by the asterisk (*, P < 0.05) based on one-way analysis of variance. Lines at the top, bottom, and middle of the box correspond to the 75th, 25th, and 50th percentiles (median), respectively. The asterisk in the box represents the mean value. Figure S3. Relative abundance of the dominant bacterial phyla (>3%) or classes (Proteobacteria) under different health state across three sampling days. Each bar represents the mean Âą standard deviation. Significant differences were indicated by the asterisk (*, P < 0.05; **, P < 0.01) based on one-way analysis of variance. Figure S4. Principal coordinate analysis (PCoA) plots of community dissimilarities based on unweighed Unifrac distance between healthy and diseased shrimp gut across three sampling days. Sampling days exhibited with distinct colors (Blue: Day 70; Red: Day 80; Green: Day 85) and health state showed with the solid (Healthy) and hollow (Diseased). Permutational Multivariate Analysis of Variance (PERMANOVA) was used to test the significance of time, health state and their interaction in community variation at each day. HI: healthy gut; DI: diseased gut.

Contrasting temperature Bacterial community Turnover rate Temperature relationship Indicator species A B S T R A C T Soil microbial communities potentially mediate the feedbacks to climate change, and thus, the understanding of microbial ecology is central to predict future global warming. However, the direct warming effects on microbial communities are uncertain due to the confounding effects of plant traits and soil heterogeneities. Here, we exposed alpine meadow soil microcosms to temperature between 10 and 40 � C for 28 days, to evaluate the temperature relationship of the bacterial community structure and microbial functions. Our results showed that sustained exposure to contrasting temperature produced compositionally and functionally distinct microbial communities. The degree of these changes was dependent on the magnitude of warming, as shown by a consistent increase in the dissimilarities and a shift of the carbon (C) use pattern along the temperature gradient. We found that the bacterial community temporal dynamics followed a gradual process of succession, and the turnover rate was substantially accelerated (P = 0.012) by warmer temperatures; every 1 � C elevation in soil temperature was estimated to increase the turnover by 0.001. Consistently, contrasting temperature was found to be the dominant factor explained 6.1% of the total variation of the microbial community structures; however, the incubation duration and the interaction between incubation temperature and duration explained 5.4% and 4.1% of the variation, respectively. As anticipated, the shift in bacterial community rapidly translated to a similar change in enzymes activities and C utilization. In addition, potential indicator species were screened; these species characterized the temperature gradient. Collectively, our findings indicate that direct warming effects on soil bacterial community could substantially alter certain function and that contrasting temperatures would accelerate the bacterial community turnover– temperature relationship in this alpine meadow soil.

The underlying mechanisms of microbial community assembly in connective coastal environments are unclear. The coastal water area of northern Zhejiang, East China Sea, is a complex marine ecosystem with multiple environmental gradients, where the distributions and determinants of bacterioplankton communities remain unclear. We collected surface water samples from 95 sites across eight zones in this area for investigating bacterial community with 16S rRNA gene high-throughput sequencing. Bacterial alpha-diversity exhibits strong associations with water chemical parameters and latitude, with 75.5% of variation explained by suspended particle. The composition of dominant phyla can group the sampling sites into four bacterial provinces, and most key discriminant phyla and families/genera of each province strongly associate with specific environmental features, suggesting that local environmental conditions shape the biogeographic provincialism of bacterial taxa. At a broader and finer phylogenetic scale, bacterial beta-diversity is dominantly explained by the shared variation of environmental and spatial factors (63.3%); meanwhile, the environmental determinants of bacterial β-diversity generally exhibit spatially structured patterns, suggesting that bacterial assembly in surface water is highly controlled by spatially structured environmental gradients in this area. This study provides evidence for the unique biogeographic pattern of bacterioplankton communities at an entire scale of this marine ecosystem.

A mesocosm experiment was conducted to study the effects of commercial microbial agents (probiotics) on the phytoplankton community structure in a shrimp (Litopenaeus vannamei) farm located in Yinzhou-Ningbo, Zhejiang Province, China. Qualitative and quantitative analyses of the phytoplankton were examined along with physico-chemical parameters in the ponds treated with microbial agents and in the untreated ponds without microbial agents. A total of 18 well-diversified species of phytoplankton belonging to Bacillariophyta, Dinoflagellata, Cyanophyta and Chlorophyta were investigated during the study period. The average phytoplankton abundance in the treated ponds (6.08 × 105 cells L−1 in HJW ponds and 7.11 × 105 cells L−1 in JK27 ponds) was significantly less than that in the control ponds (1.27 × 106 cells L−1, P 0.05). The findings of the present study suggest that the application of commercial probiotics in shrimp farms could positively influence the growth of beneficial algae, such as Bacillariophyta rather than harmful algae, such as Cyanobacteria, and thus improves the water quality, the health of the shrimp and increases production.

The key to improving the photovoltaic power generation and optimizing the performance of photovoltaic inverters is the improvement of the control method. This paper introduces two improved PI control methods, the two control methods are all using SPWM wave as the inverter power switch control signal. The algorithm is easy to be digitally implemented, the computation is small, the support effect is good for the low cost processor, so it is more advantageous in practical application. By analyzing the shortcomings of traditional PI control, the control strategy of fractional order PI is proposed. The method improves the dynamic response speed and steady state characteristics, and has better anti grid interference ability and strong load adaptability. In addition, according to the advantages and disadvantages of traditional PI control and repetitive control, a control strategy based on repetition and PI control is proposed. The method improves the output current waveform and effectively improves the dynamic response speed and steady state accuracy, and reduces the harmonic content.

Acute ecological impacts of co-contamination of polycyclic aromatic hydrocarbons (PAHs) and heavy metals on diversity and composition of coastal benthic prokaryotes were unclear. We took pyrene (Pyr) and cadmium (Cd) as the representatives and mimicked an eight-week exposure of moderate and high levels of Pyr, Cd and their mixtures. 16S rRNA amplicon sequencing was used to investigate interaction of the contaminants in temporal succession of prokaryotes. Generally, concentrations of Pyr and HCl-extractable Cd in the sediments were stable over time. Effects and interaction of Pyr and Cd on prokaryotic α-diversity were temporally- and dose-dependent with a decreasing trend in richness and Shannon index under various contamination regimes, particularly in the single-Cd contaminated groups at the early stage. Temporal variability and Pyr-induced pattern in prokaryotic composition were observed. However, Pyr and Cd showed a persistent interaction in prokaryotic composition after 7 days, altering successional trajectories of communities. The communities under Pyr contamination regardless of Cd could be at a developing stage for an active PAH-degrading community with appearance of a pioneer Cycloclasticus phylotype, persistently showing a strong correlation with Pyr level. The associations of phylotypes and Cd level were short-lived and weak, corresponding to the overall resistance of prokaryotic composition to Cd. In the high-throughput sequencing era, using microcosm experiment, we renewed the knowledge about how prokaryotes vary in terms of α-diversity, composition and specific taxa in response to co-contamination of model contaminants at a temporal scale.

Hemin-graphene nanosheets (H-GNs) can be controllably assembled by target DNA via a hybridization process. This results in a color change from dark blue-green to light blue-green. The degree of aggregation is dependent on DNA concentration and very sensitive to base mismatch. The formation of the blue-green color can be detected with bare eyes or a spectrometer. The method is simple, rapid, and works over the concentration range from 1.0 to 100 nM. The detection limit for target DNA is 0.2 nM. Excellent selectivity is also found in that a DNA with a single base mismatch can be discriminated. This was exploited to detect DNA damage as induced by styrene oxide, sodium arsenite, Fenton’s reagent, or UV radiation. We presume that this method represents a promising tool for evaluating genotoxicity.

Patterns of microbial distribution represent the integrated effects of historical and biological processes and are thus a central issue in ecology. However, there is still active debate on whether dispersal limitation contributes to microbial diversification in strongly connected systems. In this study, sediment samples were collected along a transect representing a variety of seawater pollution levels in the East China Sea. We investigated whether changes in sediment bacterial community structures would indicate the effects of the pollution gradient and of dispersal limitation. Our results showed consistent shifts in bacterial communities in response to pollution. More geographically distant sites had more dissimilar communities ( r = −0.886, P < 0.001) in this strongly connected sediment ecosystem. A variance analysis based on partitioning by principal coordinates of neighbor matrices (PCNM) showed that spatial distance (dispersal limitation) contributed more to bacterial community variation (8.2%) than any other factor, although the environmental factors explained more variance when combined (11.2%). In addition, potential indicator taxa (primarily affiliated with Deltaproteobacteria and Gammaproteobacteria ) were identified; these taxa characterized the pollution gradient. This study provides direct evidence that dispersal limitation exists in a strongly connected marine sediment ecosystem and that candidate indicator taxa can be applied to evaluate coastal pollution levels.

The close correlation between the incidence of shrimp disease and the surrounding microbial community is well established. However, it remains uncertain whether particular bacterial assemblages are indicative of shrimp health status (healthy or diseased). To test this hypothesis, we used 454 pyrosequencing to compare the bacterioplankton composition of ponds with healthy shrimp populations (PHS) with that of ponds with diseased shrimp populations (PDS). The results showed that the bacterial communities in PDS were markedly distinct (P

The aim of this study was to obtain a nitrite-oxidizing bacterium with high nitrite oxidation activity for controlling nitrite levels. A nitrite-oxidizing bacterium, ZS-1, was isolated from the water of a coastal Pseudosciaena crocea-rearing pond. The strain was identified as Nitrobacter winogradskyi based on the phylogenetic analyses of the 16S ribosomal ribonucleic acid gene and nxrA sequence of ZS-1. Under aerobic condition, the nitrite-oxidizing activity of ZS-1 did not change considerably in the range of pH 7–9, but was strongly inhibited by lower (pH = 6) and higher (pH = 10) pH values. The optimum temperature range is 25–32 °C. Lower temperature made the adaptive phase of ZS-1 longer but did not affect its maximum nitrite oxidization rate. The nitrite-oxidizing activity of ZS-1 started to be inhibited by ammonia and nitrate when the concentrations of ammonia and nitrate reached 25 mg L−1 and 100 mg L−1, respectively. The inhibition was stronger with higher concentration of ammonia or nitrate. The nitrite-oxidizing activity of ZS-1, however, was not inhibited by high concentration of nitrite (500 mg L−1). The nitrite-oxidizing activity of ZS-1 was increased by low ammonia concentration (1 mg L−1 to 10 mg L−1).

Knowledge about the drivers of benthic prokaryotic diversity and metabolic potential in interconnected coastal sediments at regional scales is limited. We collected surface sediments across six zones covering ~200 km in coastal northern Zhejiang, East China Sea and combined 16 S rRNA gene sequencing, community-level metabolic prediction, and sediment physicochemical measurements to investigate variations in prokaryotic diversity and metabolic gene composition with geographic distance and under local environmental conditions. Geographic distance was the most influential factor in prokaryotic β-diversity compared with major environmental drivers, including temperature, sediment texture, acid-volatile sulfide, and water depth, but a large unexplained variation in community composition suggested the potential effects of unmeasured abiotic/biotic factors and stochastic processes. Moreover, prokaryotic assemblages showed a biogeographic provincialism across the zones. The predicted metabolic gene composition similarly shifted as taxonomic composition did. Acid-volatile sulfide was strongly correlated with variation in metabolic gene composition. The enrichments in the relative abundance of sulfate-reducing bacteria and genes relevant with dissimilatory sulfate reduction were observed and predicted, respectively, in the Yushan area. These results provide insights into the relative importance of geographic distance and environmental condition in driving benthic prokaryotic diversity in coastal areas and predict specific biogeochemically-relevant genes for future studies.

Probiotics with antimicrobial properties can be used to regulate the microflora, control the pathogenic algae, and improve the mineralization of organic substances in the aquaculture environment. However, the efficacy of the probiotics on the succession of microalgae in the shrimp (Litopenaeus vannamei Boone) culture remains inadequate. A field experiment in mesocosm was performed to explore the impacts of probiotics on the succession of microalgae and nutrient enrichment of the shrimp culture systems. The enormous changes in the microalgae community structure (MCSs) was significantly influenced by probiotic colonization. Probiotics shifted MCSs into three seral phases and their sequential replacements of the dominant taxa were identified by cluster analysis. Moreover, each seral stage of the keystone species turnover in MCSs represents distinguished ecological functions. At the final seral stage probiotics significantly constrained the succession of the most competitive species of Cyanobacteria (Oscillatoria and Anabaena) which was disagreed with the normal seral stage. Similarly, the probiotics increased and maintained the sequel of the nutritional value of Nannochloropsis and Chlorella from Chlorophyta and Oocystics and Navicula from the Bacillariophyta. Furthermore, the probiotic-based ponds had a higher shrimp survival rate compared to the control. Nutrients concentration of nitrite (NO2−) and nitrate (NO3−) were lower in treatments than in the control. Consequently, chemical oxygen demand (COD), nitrite (NO2−), water temperature (WT), total ammonium nitrogen (TAN) and dissolved oxygen (DO) were strongly explanatory variables controlled the sequel of MCSs. These findings imply that the probiotics have potential in the succession, redistribution of beneficial microalgae, inhibit the growth of harmful Cyanobacteria and sustain the MCSs stability in shrimp aquaculture activities.

Elevated seawater temperature has altered the coupling between coastal primary production and heterotrophic bacterioplankton respiration. This shift, in turn, could influence the feedback of ocean ecosystem to climate warming. However, little is known about how natural bacterioplankton community responds to increasing seawater temperature. To investigate warming effects on the bacterioplankton community, we collected water samples from temperature gradients (ranged from 15.0 to 18.6 °C) created by a thermal flume of a coal power plant. The results showed that increasing temperatures significantly stimulated bacterial abundance, grazing rate, and altered bacterioplankton community compositions (BCCs). The spatial distribution of bacterioplankton community followed a distance similarity decay relationship, with a turnover of 0.005. A variance partitioning analysis showed that temperature directly constrained 2.01 % variation in BCCs, while temperature-induced changes in water geochemical and grazing rate indirectly accounted for 4.03 and 12.8 % of the community variance, respectively. Furthermore, the relative abundances of 24 bacterial families were linearly increased or decreased (P

Coexistence of heavy metals and organic contaminants in coastal ecosystems may lead to complicated circumstances in ecotoxicological assessment for biological communities due to potential interactions of contaminants. Consequences of metals and polycyclic aromatic hydrocarbons (PAHs) co-contamination on coastal marine microbes at the community level were paid less attention. We chose cadmium (Cd) and phenanthrene (PHE) as representatives of metals and PAHs, respectively, and mimicked contaminations using coastal water microcosms spiked with Cd (1 mg/L), PHE (1 mg/L), and their mixture over two weeks. 16S rRNA gene amplicon sequencing was used to compare individual and cumulative effects of Cd and PHE on temporal succession of bacterioplankton communities. Although we found dramatic impacts of dimethylsulfoxide (DMSO, used as a carrier solvent for PHE) on bacterial α-diversity and composition, the individual and cumulative effects of Cd and PHE on bacterial α-diversity were temporally variable showing an antagonistic pattern at early stage in the presence of DMSO. Temporal succession of bacterial community composition (BCC) was associated with temporal variability of water physicochemical parameters, each of which explained more variation in BCC than two target contaminants did. However, Cd, PHE, and their mixture distinctly altered the successional trajectories of BCC, while only the effect of Cd was retained at the end of experiment, suggesting certain resilience in BCC after the complete dissipation of PHE along the temporal trajectory. Moreover, bacterial assemblages at the genus level associated with the target contaminants were highly time-dependent and more unpredictable in the co-contamination group, in which some genera possessing hydrocarbon-degrading members might contribute to PHE degradation. These results provide preliminary insights into how co-exposure of Cd and PHE phylogenetically alters successional trajectories of bacterioplankton communities in the manipulated coastal water microcosms.

Silver nanoparticles (AgNPs) demonstrating good antimicrobial activity are widely used in many fields. However, the impact of AgNPs on the community structures of marine biofilms that drive biogeochemical cycling processes and the recruitment of marine invertebrate larvae remains unknown. Here, we employed MiSeq sequencing technology to evaluate the bacterial communities of 28-day-old marine biofilms formed on glass, polydimethylsiloxane (PDMS), and PDMS filled with AgNPs and subsequently tested the influence of these marine biofilms on plantigrade settlement by the mussel Mytilus coruscus. AgNP-filled PDMS significantly reduced the dry weight and bacterial density of biofilms compared with the glass and PDMS controls. AgNP incorporation impacted bacterial communities by reducing the relative abundance of Flavobacteriaceae (phylum: Bacteroidetes) and increasing the relative abundance of Vibrionaceae (phylum: Proteobacteria) in 28-day-old biofilms compared to PDMS. The settlement rate of M. coruscus on 28-day-old biofilms developed on AgNPs was lower by >30% compared to settlement on control biofilms. Thus, the incorporation of AgNPs influences biofilm bacterial communities in the marine environment and subsequently inhibits mussel settlement.

Additional file 1: Table S1. Measurements of geochemical factors of the 10 sampling sites. Table S2. Pearson correlations between seawater temperature and biogeochemical variables. Figure S1. Pearson correlations between seawater temperature and bacterial abundance (A), DNA yield (a proxy for microbial biomass) (B), and grazing rate (C). Figure S2. Multivariate regression tree (MRT) of bacterial diversity associated with driving biogeochemical factors.

The kinetic and thermodynamic behaviors of cationic dye adsorption onto citric acid esterifying wheat straw (EWS) from aqueous solution were investigated. Two cationic dyes, methylene blue (MB) and crystal violet (CV) were selected as adsorbates. The kinetic and thermodynamic parameters of dye adsorption were examined with a batch system by changing various experimental factors (e.g. initial pH, EWS dosage, dye concentration, contact time, temperature). The MB and CV removal ratios came up to the maximum value beyond pH 4. The 2.0 g/L or up of EWS could almost completely remove MB and CV from 250 mg/L of dye solution. The adsorption percentages of MB and CV kept above 95% over a range from 50 to 350 mg/L of dye concentration when 2.0 g/L of EWS was used. The isothermal data followed the Langmuir model. The adsorption processes could be described by the pseudosecond-order kinetic model. The dual linear plots of intraparticle diffusion indicated that two intraparticle diffusion steps occurred in the dye adsorption processes. The thermodynamic study indicated that the adsorptions of dyes were spontaneous and endothermic. High temperatures favored the adsorption processes.

In this paper, the solid phase preparation method of a cationic sorbent, which bears hydroxyl groups of phosphoric acid derived from esterified soybean hull (ESH), was reported. The sorption kinetics and thermodynamics of two basic dyes, acridine orange (AO) and malachite green (MG), from aqueous solution onto ESH were investigated with a batch system. The isothermal data of dye sorptions followed the Langmuir model better than the Freundlich model. The maximum sorption capacity ( Q m ) of ESH for AO and MG was 238.1 mg/g and 178.57 mg/g, respectively. The dye sorption processes could be described by the pseudo-second-order kinetic model. The thermodynamic study indicated that the dye sorptions were spontaneous and exothermic. Lower temperatures were favorable for the sorption processes.

This paper reports the preparation of a phosphorylated cotton chelator (PCC) by solid phase esterification of phosphoric acid (PA) onto defatted cot- ton fibres using urea as the catalyst. The synthesized PCC was employed for the preconcentration of copper from water samples prior to its determination by flame atomic absorption spectrometry (FAAS). The preconcentration of copper was studied under both batch and column techniques. The pH range for the quantitative preconcentration of copper was 4.0-7.0. The sorption time requi- red for each sample was less than 30 min by the batch method. The copper sorption capacity of the PCC was found to be 15.3 mg/g at the optimum pH value. Elution with 1.0 mol dm -3 hydrochloric acid was found to be quantita- tive. Feasible flow rates of the copper solution for quantitative sorption onto the column packed with PCC were 0.5-4.0 ml min -1 , whereas the optimum flow rate of the hydrochloric acid solution for desorption was less than 1.5 ml min -1 . An 80-fold preconcentration factor could be achieved under the optimum co- lumn conditions. The tolerance limits for common metal ions on the precon- centration of copper and the number of times of column reuse were investiga- ted. The proposed method was successfully applied for the preconcentration and determination of trace copper in natural and drinking water samples by FAAS.

We report on the molecular cloning and characterization of penicillin V acylase (PVA) from an actinomycete, Streptomyces mobaraensis ( Sm -PVA), which was originally isolated as an acylase that efficiently hydrolyzes the amide bond of various N -fatty-acyl- l -amino acids and N -fatty-acyl-peptides as well as capsaicin (8-methyl- N -vanillyl-6-nonenamide). In addition, the purified Sm -PVA hydrolyzed penicillin V with the highest activity ( k cat ) among the PVAs so far reported, penicillin G, and 2-nitro-5-phenoxyacetamide benzoic acid. The BLAST search revealed that the Sm -PVA precursor is composed of a polypeptide that is characteristic of enzymes belonging to the β-lactam acylase family with four distinct segments; a signal sequence (43 amino acids), an α subunit (173 amino acids), a linker peptide (28 amino acids), and a β subunit (570 amino acids). The mature, active Sm -PVA is a heterodimeric protein with α and β subunits, in contrast to PVAs isolated from Bacillus sphaericus and B. subtilis , which have a homotetrameric structure. The amino acid sequence of Sm -PVA showed identities to PVA from S . lavendulae , N -acylhomoserine lactone-degrading acylase from Streptomyces sp., cyclic lipopeptide acylase from Streptomyces sp., and aculeacin A acylase from Actinoplanes utahensis with 68, 67, 67, and 41% identities, respectively.

Understanding the underlying mechanisms that shape the temporal dynamics of a microbial community has important implications for predicting the trajectory of an ecosystem’s response to anthropogenic disturbances. Here, we evaluated the seasonal dynamics of bacterioplankton community composition (BCC) following more than three decades of mariculture disturbance in Xiangshan Bay. Clear seasonal succession and site (fish farm and control site) separation of the BCC were observed, which were primarily shaped by temperature, dissolved oxygen and sampling time. However, the sensitive bacterial families consistently changed in relative abundance in response to mariculture disturbance, regardless of the season. Temporal changes in the BCC followed the time-decay for similarity relationship at both sites. Notably, mariculture disturbance significantly (P

Along with the socio-economic development and people's living standards constantly improving, demand for beverages and alcohol increases. Therefore the high-end industrial automatic filling equipment are also promoted. This paper designs and manufactures a liquid filling machine intelligent control system for automated production line of beer. This system is composed by HOLLSYS LM3106A PLC (Programmable Logic Controller) and Hollyview industrial control configuration software and Shihlin SS22-023-0.75K inverter composition. We conducted energy dissipation test experiment and canned beer production experiment based on PID control. The experiment proves that the production efficiency of the system has improved the percent of 11.27. Energy consumption of the system has also reduced. So the system which has Advantage of high working efficiency and energy saving can be applied in production in the future.