Endogenous bacteria inhabiting the Ophiocordyceps highlandensis during fruiting body development

Molecular phylogenetics of the Umbelopsis genus-identification of new species and evaluation of their oil application value

AIMS

The aim of this study was to reconstruct the evolutionary framework of the genus Umbelopsis by using modern taxonomic strategies and evaluating the quality of oil and prospective uses of three distinct species.

METHODS AND RESULTS

Three species of Umbelopsis were identified based on morphological characteristics and phylogenetic evidence obtained from three genes (ITS, LSU, and ACT). A new species of Umbelopsis was described and illustrated, and subsequently named U. ophiocordycipiticola. The characteristics of U. ophiocordycipiticola exhibited sporangia with a diameter ranging from 8 to 17 µm. and sporangiospores that were oval to ellipsoidal in shape, irregularly angular, with dimensions of ∼1.9-2.9 × 1.7-3.0 µm. Gas chromatography and mass spectrometry (GC-MS) were used to examine the composition of fatty acids. Notably, U. ophiocordycipiticola showed a significantly higher oil content of 50.89% in dry cell weight (DCW) compared to U. vinacea and U. ramanniana. The mean proportion of polyunsaturated fatty acids (PUFAs) in U. ophiocordycipiticola was 32.38%, and the maximum levels of γ-linolenic acid (GLA), arachidonic acid (ARA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) in U. ophiocordycipiticola were found to be 14.51, 0.24, 0.54, and 0.53%, respectively. The biodiesel quality from all three species complied with applicable standards set by the American Association for Testing and Materials (ASTM 6751) and the Brazilian National Petroleum Agency (ANP 255).

CONCLUSIONS

The establishment of a novel species, U. ophiocordycipiticola, was strongly supported by morphological and molecular evidence. Umbelopsis ophiocordycipiticola exhibited a high-value PUFA content. Additionally, three Umbelopsis species demonstrated good quality for biodiesel production.

Effects of the polyhalogenated carbazoles 3-bromocarbazole and 1,3,6,8-tetrabromocarbazole on soil microbial communities

Soil ecosystems are being more contaminated with polyhalogenated carbazoles (PHCZs), which raising much attention about their impact on soil microorganisms. 3-Bromocarbazole (3-BCZ) and 1,3,6,8-tetrabromocarbazole (1,3,6,8-TBCZ) are two typical PHCZs with high detection rates in the soil environment. However, ecological risk research on these two PHCZs in soil is still lacking. In the present study, after 80 days of exposure, the ecological influence of 3-BCZ and 1,3,6,8-TBCZ was investigated based on 16S rDNA sequencing, ITS sequencing, gene (16S rDNA, ITS, amoA, nifH, narG and cbbL) abundance and soil enzyme activity. The results showed that the bacterial 16S rDNA gene abundance significantly decreased under 3-BCZ and 1,3,6,8-TBCZ exposure after 80 days of incubation. The fungal ITS gene abundance significantly decreased under 1,3,6,8-TBCZ (10 mg/kg) exposure. PHCZs contributed to the alteration of bacteria and fungi community abundance. Bacteria Sphingomonas, RB41 and fungus Mortierella, Cercophora were identified as the most dominant genera. The two PHCZs consistently decreased the relative abundance of Sphingomonas, Lysobacter, Dokdonella, Mortierella and Cercophora etc at 80th day. These keystone taxa are related to the degradation of organic compounds, carbon metabolism, and nitrogen metabolism and may thus have influence on soil ecological functions. Bacterial and fungal functions were estimated using functional annotation of prokaryotic taxa (FAPROTAX) and fungi functional guild (FUNGuild), respectively. The nitrogen and carbon metabolism pathway were affected by 3-BCZ and 1,3,6,8-TBCZ. The soil nitrogen-related functions of aerobic ammonia oxidation were decreased but the soil carbon-related functions of methanol oxidation, fermentation, and hydrocarbon degradation were increased at 80th day. The effects of 3-BCZ and 1,3,6,8-TBCZ on the abundances of the amoA, nifH, narG, and cbbL genes showed a negative trend. These results elucidate the ecological effects of PHCZs and extend our knowledge on the structure and function of soil microorganisms in PHCZ-contaminated ecosystems.

Compositional and functional diversities of core microbial communities in wild and artificial Ophiocordyceps sinensis

Ophiocordyceps sinensis is an entomogenous fungus, and its wildlife resource is very insufficient, as it is widely traded as a natural health product. The artificial culture of O. sinensis is a remarkably effective progress in addressing the problem. Adding microorganisms may improve the process of artificial culture. To analyse the composition and function of the microbial community, high-throughput sequencing was used to explore the microbial community inhabiting wild and artificial O. sinensis and surrounding soil. Significant differences in the microbial communities across groups were revealed by the PCoA analysis. There were 51 fungal and 598 bacterial operational taxonomic units only being assigned to the fruiting bodies of wild O. sinensis (Wf) by the Venn diagram. From the LEfSe analysis, 39 fungal taxa and 75 bacterial taxa were enriched in Wf. Enzymes that were highly abundant in the core fungi were involved in physiological metabolic processes. Metabolic pathways were dominated in the core bacteria, followed by environmental information processing. The core microorganisms, with the marked differences between Wf and the other three groups, were essential for wild O. sinensis. Functional analysis verified their involvement in the growth, development, and infection of O. sinensis. These core microorganisms may be a valuable resource for the artificial culture of O. sinensis.

Impact of Cultivation Substrate and Microbial Community on Improving Mushroom Productivity: A Review

Simple Summary

Lignocellulosic material and substrate formulations affect mushroom productivity. The microbial community in cultivation substrates affects the quality of the substrates and the efficiency of mushroom production. The elucidation of the key microbes and their biochemical function can serve as a useful guide in the development of a more effective system for mushroom cultivation.

Abstract

Lignocellulosic materials commonly serve as base substrates for mushroom production. Cellulose, hemicellulose, and lignin are the major components of lignocellulose materials. The composition of these components depends upon the plant species. Currently, composted and non-composted lignocellulosic materials are used as substrates in mushroom cultivation depending on the mushroom species. Different substrate compositions can directly affect the quality and quantity of mushroom production yields. Consequently, the microbial dynamics and communities of the composting substrates can significantly affect mushroom production. Therefore, changes in both substrate composition and microbial diversity during the cultivation process can impact the production of high-quality substrates and result in a high degree of biological efficiency. A brief review of the current findings on substrate composition and microbial diversity for mushroom cultivation is provided in this paper. We also summarize the advantages and disadvantages of various methods of mushroom cultivation by analyzing the microbial diversity of the composting substrates during mushroom cultivation. The resulting information will serve as a useful guide for future researchers in their attempts to increase mushroom productivity through the selection of suitable substrate compositions and their relation to the microbial community.

Possible impacts of the predominant Bacillus bacteria on the Ophiocordyceps unilateralis s. l. in its infected ant cadavers

Animal hosts infected and killed by parasitoid fungi become nutrient-rich cadavers for saprophytes. Bacteria adapted to colonization of parasitoid fungi can be selected and can predominate in the cadavers, actions that consequently impact the fitness of the parasitoid fungi. In Taiwan, the zombie fungus, Ophiocordyceps unilateralis sensu lato (Clavicipitaceae: Hypocreales), was found to parasitize eight ant species, with preference for a principal host, Polyrhachis moesta. In this study, ant cadavers grew a fungal stroma that was predominated by Bacillus cereus/thuringiensis. The bacterial diversity in the principal ant host was found to be lower than the bacterial diversity in alternative hosts, a situation that might enhance the impact of B. cereus/thuringiensis on the sympatric fungus. The B. cereus/thuringiensis isolates from fungal stroma displayed higher resistance to a specific naphthoquinone (plumbagin) than sympatric bacteria from the environment. Naphthoquinones are known to be produced by O. unilateralis s. l., and hence the resistance displayed by B. cereus/thuringiensis isolates to these compounds suggests an advantage to B. cereus/thuringiensis to grow in the ant cadaver. Bacteria proliferating in the ant cadaver inevitably compete for resources with the fungus. However, the B. cereus/thuringiensis isolates displayed in vitro capabilities of hemolysis, production of hydrolytic enzymes, and antagonistic effects to co-cultured nematodes and entomopathogenic fungi. Thus, co-infection with B. cereus/thuringiensis offers potential benefits to the zombie fungus in killing the host under favorable conditions for reproduction, digesting the host tissue, and protecting the cadaver from being taken over by other consumers. With these potential benefits, the synergistic effect of B. cereus/thuringiensis on O. unilateralis infection is noteworthy given the competitive relationship of these two organisms sharing the same resource.