Isolation and identification of pathogens of Morchella sextelata bacterial disease.

Morel mushroom (Morchella spp.) is a rare edible and medicinal fungus distributed worldwide. It is highly desired by the majority of consumers. Bacterial diseases have been commonly observed during artificial cultivation of Morchella sextelata. Bacterial pathogens spread rapidly and cause a wide range of infections, severely affecting the yield and quality of M. sextelata. In this study, two strains of bacterial pathogens, named M-B and M-5, were isolated, cultured, and purified from the tissues of the infected M. sextelata. Koch's postulates were used to determine the pathogenicity of bacteria affecting M. sextelata, and the pathogens were identified through morphological observation, physiological and biochemical analyses, and 16S rRNA gene sequence analysis. Subsequently, the effect of temperature on the growth of pathogenic bacteria, the inhibitory effect of the bacteria on M. sextelata on plates, and the changes in mycelial morphology of M. sextelata mycelium were analyzed when M. sextelata mycelium was double-cultured with pathogenic bacteria on plates. The results revealed that M-B was Pseudomonas chlororaphis subsp. aureofaciens and M-5 was Bacillus subtilis. Strain M-B started to multiply at 10-15°C, and strain M-5 started at 15-20°C. On the plates, the pathogenic bacteria also produced significant inhibition of M. sextelata mycelium, and the observation of mycelial morphology under the scanning electron microscopy revealed that the inhibited mycelium underwent obvious drying and crumpling, and the healthy mycelium were more plump. Thus, this study clarified the pathogens, optimal growth environment, and characteristics of M. sextelata bacterial diseases, thereby providing valuable basic data for the disease prevention and control of Morchella production.

[Effect of Continuous Cropping on the Physicochemical Properties, Microbial Activity, and Community Characteristics of the Rhizosphere Soil of Codonopsis pilosula].

Effects of continuous cropping on rhizosphere soil physical and chemical properties, soil microbial activity, and community characteristics of Codonopsis pilosula were investigated. The C. pilosula plot(CK) fallow for five years and C. pilosula fields with different years of continuous cropping were studied using Illumina high-throughput sequencing technology combined with soil physical and chemical properties analysis. The response of rhizosphere soil physical and chemical properties, microbial activities, and microbial community characteristics to continuous cropping years of C. pilosula were investigated. The results were as follows:the contents of organic carbon, total phosphorus, total nitrogen, and salt in rhizosphere soil of C. pilosula increased with the extension of continuous cropping years. However, soil pH value decreased with the extension of continuous cropping years. Compared with that in the CK treatment, rhizosphere soil organic carbon content of C. pilosula in continuous cropping for one, two, three, and four years increased by 11.1%, 80.5%, 74.9%, and 78.2%, respectively. Total phosphorus content increased by 11.8%, 52.9%, 66.7%, and 78.4%, and total nitrogen content increased by 31.3%, 68.8%, 52.1%, and 56.3%, respectively. Soil salt content increased significantly under continuous cropping of three and four years, and soil conductivity increased by 54.2% and 84.7% compared with that in the CK treatment, respectively. The C/N ratio of microbial biomass in rhizosphere soil exhibited an increasing trend with the extension of continuous cropping years. Soil respiration entropy and microbial entropy showed a decreasing trend. With the increase in continuous cropping years, the diversity and abundance of bacteria in soil decreased, whereas the diversity and abundance of fungi increased. In addition, with the increase in continuous cropping years, the antagonistic effect between bacterial communities was enhanced, whereas the synergistic effect between fungal communities was mainly observed. Correlation analysis showed that soil total phosphorus, available potassium, carbon to nitrogen ratio of microbial biomass, soil respiration entropy, microbial biomass carbon, and electrical conductivity were the main factors affecting the changes in soil bacterial community characteristics. Soil total nitrogen, available potassium, available phosphorus, and soil respiration entropy were the main factors affecting the changes in fungal community characteristics. In conclusion, continuous cropping significantly changed the physical and chemical properties of soil and microbial activity and affected the abundance and diversity of bacteria and fungi in soil. This changed the interaction between microorganisms, which disrupted the stability of microbial communities in the soil.

Community composition and trophic mode diversity of fungi associated with fruiting body of medicinal Sanghuangporus vaninii.

BACKGROUND: The microbial symbionts of macrofungal fruiting body have been shown to play momentous roles in host growth, development, and secondary metabolism. Nevertheless, there is no report on the fungal diversity of Sanghuangporus, a medicinal and edible homologous macrofungus as "forest gold", which has good effects on antioxidation, boosting immunity and curing stomachache. Here, the diversity and functional group of fungi associated with the fruiting body of the most widely applied S. vaninii were characterized by high-throughput sequencing and FUNGuild tool for the first time. RESULTS: Total 11 phyla, 34 classes, 84 orders, 186 families, and 328 genera were identified in the fruiting body, and our results revealed that the fungal community was dominated by the host fungal taxonomy with absolute superiority (more than 70%), namely, Basidiomycota, Agaricomycetes, Hymenochaetales, Hymenochaetaceae, and genus of Phellinus corrected to Sanghuangporus. Simultaneously, the reads allocated into non-host fungal operational taxonomic units were largely dominated by Ascomycota, Sordariomycetes, Sordariales, Mortierellaceae, and Mortierella. Furthermore, the endophytic fungi were assigned into three trophic modes of "saprotroph" (53.2%), "symbiotroph" (32.2%), and "pathotroph" (14.1%), in which the category of "plant pathogen" was highest enriched with relative abundance of 91.8%, indicating that the endophytic fungi may have the potential to adjust the growth and metabolism of host S. vaninii. CONCLUSION: Altogether, this report firstly provided new findings that can be inspiring for further in-depth studies to exploit bioactive microbial resources for increased production of Sanghuangporus via coculture, as well as to explore the relationship between macrofungi and their associated endophytes.

In silico analysis of epitope-based vaccine candidate against tuberculosis using reverse vaccinology.

Tuberculosis (TB) kills more individuals in the world than any other disease, and a threat made direr by the coverage of drug-resistant strains of Mycobacterium tuberculosis (Mtb). Bacillus Calmette-Guérin (BCG) is the single TB vaccine licensed for use in human beings and effectively protects infants and children against severe military and meningeal TB. We applied advanced computational techniques to develop a universal TB vaccine. In the current study, we select the very conserved, experimentally confirmed Mtb antigens, including Rv2608, Rv2684, Rv3804c (Ag85A), and Rv0125 (Mtb32A) to design a novel multi-epitope subunit vaccine. By using the Immune Epitopes Database (IEDB), we predicted different B-cell and T-cell epitopes. An adjuvant (Griselimycin) was also added to vaccine construct to improve its immunogenicity. Bioinformatics tools were used to predict, refined, and validate the 3D structure and then docked with toll-like-receptor (TLR-3) using different servers. The constructed vaccine was used for further processing based on allergenicity, antigenicity, solubility, different physiochemical properties, and molecular docking scores. The in silico immune simulation results showed significant response for immune cells. For successful expression of the vaccine in E. coli, in-silico cloning and codon optimization were performed. This research also sets out a good signal for the design of a peptide-based tuberculosis vaccine. In conclusion, our findings show that the known multi-epitope vaccine may activate humoral and cellular immune responses and maybe a possible tuberculosis vaccine candidate. Therefore, more experimental validations should be exposed to it.

A bibliometric-based analysis of the high-value application of Chlorella.

This bibliometric-based review analyses the trends in 1010 published articles (1990 to mid-2018) on the high-value application of Chlorella, and illustrates the evolution and latest tendencies at a global level by the number of publications and their distribution, issuing institutions and countries or regions, the sources and research direction, as well as the core-author and keywords. The results demonstrated that there is a burst in terms of the number of articles, and China, USA, Mexico, and Japan are the dominant countries in this area. The most relevant journals with this subject are Bioresource Technology and Hydrobiology, and the research mainly focuses on marine and freshwater biology, biotechnology and applied microbiology, energy and fuels, food science and technology, and environmental sciences. Overall, bibliometric analysis has shown that Chlorella application research is a very active field, and the future research will be conducted into construction of genetic engineering algae, high-density and low-cost culture systems, efficient harvesting and separation techniques, effective energy conversion, integrated photo-bioreactors, and molecular biology technology. Wastewater treatment, CO2 bio-fixation, biomass production, and biosynthesis of useful substances by cultivating microalgae are promising research fields.

Light irradiation can regulate the growth characteristics and metabolites compositions of Rhodotorula mucilaginosa.

Light is an important factor that can induce the growth of varieties of organisms including fungi and their secondary metabolites. The evolutions of biomass, carotenoids, lipid production, compositions and contents of fatty acid and amino acid in Rhodotorula mucilaginosa were investigated under different light irradiation conditions. The results indicated that irradiation with 1700 lx could promote the growth and glucose assimilation of R. mucilaginosa, compared to the dark control, while the trial with 3500 lx had certain inhibiting effects. The carotenoids concentrations and percentages of unsaturated fatty acid (USFA, C16:1 and C18:1) increased with the improvement of irradiation intensity. Conversely, the proportions of saturated fatty acids (C16:0, C18:0 and C20:0) were decreased. The relative contents of amino acid and total protein were reduced under illumination compared to dark control. Conclusively, irradiation could change the cell growth and metabolites of the pigmented fungus, which implied that there may be a photoinduced mode exists in R. mucilaginosa similar to that of Neurospora crassa, and it also could be applied to regulate the biosynthesis and production of valuable components such as carotenoids and USFA.

Growth behavior, glucose consumption and phenol removal efficiency of Chlorella vulgaris under the synergistic effects of glucose and phenol.

The use of algae is an effective approach to remove phenol and its derivatives from polluted water. The growth behavior, glucose consumption and phenol removal efficiency of Chlorella vulgaris under the synergistic effects of glucose and phenol were investigated. The evolutions of tolerance and removal efficiency of C. vulgaris to phenol under different trophic modes and glucose contents were observed. The results revealed that growth of C. vulgaris were inhibited with the increase of phenol from 0 to 400 mg L-1 in culture media; the tolerance to phenol enhanced with the addition of glucose from 2 to 10 g L-1, while glucose consumption was inhibited with the increase of phenol content; phenol removal efficiency varied with glucose concentrations in mixotrophic media. The finding suggested that phenol inhibited the growth of C. vulgaris and glucose assimilation under mixotrophic cultivation, while appropriate glucose addition could enhance the tolerance of C. vulgaris to phenol and affect the phenol removal efficiency.

[Effects of different trophic modes on growth characteristics, metabolism and cellular components of Chlorella vulgaris].

OBJECTIVE: We studied the effects of trophic modes related to glucose and light (photoautotrophy, mixotrophy and heterotrophy) on growth, cellular components and carbon metabolic pathway of Chlorella vulgaris. METHODS: The parameters about growth of algal cells were investigated by using spectroscopy and chromatography techniques. RESULTS: When trophic mode changed from photoautotrophy to mixotrophy and to heterotrophy successively, the concentrations of soluble sugar, lipid and saturated C16/C18 fatty acids in C. vulgaris increased, whereas the concentrations of unsaturated C16, C18 fatty acids, proteins, photosynthetic pigments and 18 relative amino acids decreased. Light and glucose affect the growth, metabolism and the biochemical components biosynthesis of C. vulgaris. Addition of glucose can promote algal biomass accumulation, stimulate the synthesis of carbonaceous components, but inhibit nitrogenous components. Under illumination cultivation, concentration and consumption level of glucose decided the main trophic modes of C. vulgaris. CONCLUSION: Mixotrophic and heterotrophic cultivation could promote the growth of algal cells.

[Diversity of uncultured actinomycetes in saline-alkali soil from Jiuquan area of Hexi Corridor].

ABSTRACT: In order to more accurately understand community structure and diversity of actinomycetes in saline-alkali soil from Jiuquan area of Hexi Corridor, the community structure and diversity from three kinds of soil samples (primary, secondary saline alkali soil and farmland soil) were analyzed using uncultured methods. The results showed that the 16S rDNA clone library of actinomycetales from the primary saline-alkali soil belonged to 19 OTUs, Micrococcineae, Propionibacterineae, Corynebacterineae, Frankineae, Pseudonocardineae and unknown groups of Actinomycetales; the 16S r DNA clone library of actinomycetales from the secondary saline-alkali soil belonged to 14 OTUs, Micrococcineae, Propionibacterineae, Corynebacterineae, Frankineae, Pseudonocardineae and unknown groups of Actinomycetales; the 16S rDNA clone library of farmland soil belonged to 7 OTUs, Micrococcineae, Propionibacterineae, Corynebacterineae, Frankineae, Pseudonocardineae and unknown groups of Actinomycetales; Micrococcineae was the common population in the three soils, and also was the dominant population in primary saline alkali soil and farmland soil. The diversity index and rarefaction curves analysis showed that actinomycetes species richness was in order of primary saline-alkali soil > secondary saline-alkali soil > farmland soil. The dilution curves of primary saline-alkali soil and secondary saline-alkali soil were not leveled off, which indicated the actinomycetes diversity in saline-alkali soil was more enriched than the actual. The rich and diverse actinomycetes resources in saline-alkali soil from Jiuquan area of Hexi Corridor provide important data on the actinomycetes ecology distribution research, exploitation and utilization in saline-alkali soil.

Study of phenol biodegradation using Bacillus amyloliquefaciens strain WJDB-1 immobilized in alginate-chitosan-alginate (ACA) microcapsules by electrochemical method.

An aerobic microorganism with an ability to utilize phenol as sole carbon and energy source was isolated from phenol-contaminated wastewater samples. The isolate was identified as Bacillus amyloliquefaciens strain WJDB-1 based on morphological, physiological, and biochemical characteristics, and 16S rDNA sequence analysis. Strain WJDB-1 immobilized in alginate-chitosan-alginate (ACA) microcapsules could degrade 200 mg/l phenol completely within 36 h. The concentration of phenol was determined using differential pulse voltammetry (DPV) at glassy carbon electrode (GCE) with a linear relationship between peak current and phenol concentration ranging from 2.0 to 20.0 mg/l. Cells immobilized in ACA microcapsules were found to be superior to the free suspended ones in terms of improving the tolerance to the environmental loadings. The optimal conditions to prepare microcapsules for achieving higher phenol degradation rate were investigated by changing the concentrations of sodium alginate, calcium chloride, and chitosan. Furthermore, the efficiency of phenol degradation was optimized by adjusting various processing parameters, such as the number of microcapsules, pH value, temperature, and the initial concentration of phenol. This microorganism has the potential for the efficient treatment of organic pollutants in wastewater.

Analysis of bacterial community structure in the natural circulation system wastewater bioreactor by using a 16S rRNA gene clone library.

A variety of physical and chemical parameters are routinely monitored during operation of the Natural Circulation System, a wastewater purification bioreactor in which only natural materials and no synthetic chemicals are used. However, the microbial community structures existing in the Natural Circulation System have not been well characterized. Thus, bacterial community structure and composition in this system were studied using clone library analysis of 16S ribosomal RNA genes amplified using PCR with universal bacterial primer sets. The PCR products were then subcloned into the pGEM-T vector. Each unique restriction fragment length polymorphism pattern, created by using two pairs of restriction endonucleases, was designated as an operational taxonomic unit (OTU). The Natural Circulation System comprises five tanks, the second and third of which play a major role in the bioreactor. Clone library pro-files and principal component analysis revealed differences in the bacterial community structures of the second (anaerobic chamber) and the third (aerobic chamber) tanks. However, the beta-proteobacteria, Bacteroidetes/ Chlorobi and gamma-proteobacteria groups were dominant in both tanks. Bacterial composition was more complex in the second tank (107 OTUs) than in the third tank (68 OTUs). Of a total of 154 OTUs in the clone libraries, only 21 were common to the two tanks. The results obtained in this study should provide important information for future research into and management of the Natural Circulation System wastewater bioreactor.

[Research advances in biodegradation of chlorophenols in environment].

This paper examines the biodegradation of chlorophenols by microbes and deals with the chlorophenols-degrading microbes and the usage of biotechnology with special emphasis on degradation mechanisms. Dechlorination is the first critical step in the bacterial degradation of many chloroniated pollutans. Under aerobic condition, the degradation of mono- and dichlorophenols is shown to be initiated by oxygenation into chlorocatechols, and dechlorination occurs only after ring cleavage of the chlorocatechols. The degradation of polychlorinated phenols starts by hydrolytic para-hydroxylation, yielding chlorinated para-hydroquinone. The anaerobic biodegradation of chlorophenols occurs by reductive dechlorination, a process by which chlorines are replaced with hydrogen.