Antibiotic feeding changes the bacterial community of Chilo suppressalis and thereby affects its pesticide tolerance.

BACKGROUND: Owing to the widespread use of chemical pesticides to control agricultural pests, pesticide tolerance has become a serious problem. In recent years, it has been found that symbiotic bacteria are related to pesticides tolerance. To investigate the potential role of microorganisms in the pesticide tolerance of Chilo suppressalis, this study was conducted. RESULTS: The insect was fed with tetracycline and cefixime as the treatment group (TET and CFM, respectively), and did not add antibiotics in the control groups (CK). The 16S rDNA sequencing results showed that antibiotics reduced the diversity of C. suppressalis symbiotic microorganisms but did not affect their growth and development. In bioassays of the three C. suppressalis groups (TET, CFM, and CK), a 72 h LC50 fitting curve was calculated to determine whether long-term antibiotic feeding leads to a decrease in pesticide resistance. The CK group of C. suppressalis was used to determine the direct effect of antibiotics on pesticide tolerance using a mixture of antibiotics and pesticides. Indirect evidence suggests that antibiotics themselves did not affect the pesticide tolerance of C. suppressalis. The results confirmed that feeding C. suppressalis cefixime led to a decrease in the expression of potential tolerance genes to chlorantraniliprole. CONCLUSIONS: This study reveals the impact of antibiotic induced changes in symbiotic microorganisms on the pesticide tolerance of C. suppressalis, laying the foundation for studying the interaction between C. suppressalis and microorganisms, and also providing new ideas for the prevention and control of C. suppressalis and the creation of new pesticides.

Isolation of a feather-degrading strain of bacterium from spider gut and the purification and identification of its three key enzymes.

A novel feather-degrading bacterium named CA-1 was isolated from the gut of the spider Chilobrachys guangxiensis, which degrades native whole chicken feathers within 20 h. The CA-1 was confirmed to belong to Stenotrophomonas maltophilia based on morphologic and molecular analysis. Maximum feather degradation activity of the bacterium was observed at 37 °C in basal feather medium (NaCl 0.5 g/L, KH2PO4 0.3 g/L, K2HPO4 0.4 g/L, feather powder 10.0 g/L, pH 8.0), which was inhibited when glucose and ammonium nitrate were added in the medium. Furthermore, the purified enzymes under the optimal and suppressive conditions were analyzed respectively by SDS-PAGE and LC-MS/MS. Three enzymes, namely alkaline serine protease (29.1 kDa), ABC transporter permease (27.5 kDa), and alkaline phosphatase (40.8 kDa), were isolated and identified from the supernatant of the optimal culture and were considered to play principal roles. On the other hand, the potential synergic effects of the three proteins in S. maltophilia CA-1 feather degradation system were analyzed theoretically. CA-1 may product outer-membrane vesicles comprised of membranes and periplasmic proteins in the feather medium. The newly identified CA-1 and its synergic enzymes provide a new insight into further understanding the molecular mechanism of feather degradation by microbes. They also have potential application in cost-effectively degrading feathers into feeds and fertilizers through careful optimization and engineering of the three newly identified enzymes.

[Chemical constituents of liquid culture of symbiotic Chaetomium globosum ML-4 of oyster and their in vitro antitumor activity].

Isolation and purification of chemical constituents of liquid culture of symbiotic Chaetomium globosum ML-4 of oyster was performed through silica gel column chromatography, gel filtration over Sephadex LH-20, preparative TLC and HPLC. Five compounds were obtained and their structures were determined as chaetoglobosin V(1), chaetoglobosin Vb(2), tyrosol(3), 5-methyluracil(4)and uracil(5), respectively, based on HR-MS and NMR data and comparison with literatures. In vitro cytotoxicity of compounds against human hepatocellular carcinoma cell line SMMC-7721 were measured byMTT method, and results showed that compound 1 could obviously inhibit the proliferation of SMMC-7721 cells with an IC50 value of 60.5 mg•L⁻¹, while the IC50 value of positive control cisplatin was 19.96 mg•L⁻¹. Further studies discovered that compound 1 could lead to G2 phase arrest in SMMC-7721 cells and induce SMMC-7721 cells apoptosis. The ratio of Bcl-2/Bax in SMMC-7721 cells was decreased. The expression of protein Caspases-3,-8,-9 was improved and the expression and phosphorylation level of Akt were reduced. Aforementioned results revealed that in vitro antitumor activity of compound 1 against SMMC-7721 cells were related to G2 phase cell cycle arrest and induced-apoptosis. The induced-apoptosis was involved in both the mitochondrial pathway and the death receptor pathway and connected with activity decline of PI3K/Akt signaling pathway.

Impact of Nutrient Enrichment on Community Structure and Co-Occurrence Networks of Coral Symbiotic Microbiota in Duncanopsammia peltata: Zooxanthellae, Bacteria, and Archaea.

Symbiotic microorganisms in reef-building corals, including algae, bacteria, archaea, fungi, and viruses, play critical roles in the adaptation of coral hosts to adverse environmental conditions. However, their adaptation and functional relationships in nutrient-rich environments have yet to be fully explored. This study investigated Duncanopsammia peltata and the surrounding seawater and sediments from protected and non-protected areas in the summer and winter in Dongshan Bay. High-throughput sequencing was used to characterize community changes, co-occurrence patterns, and factors influencing symbiotic coral microorganisms (zooxanthellae, bacteria, and archaea) in different environments. The results showed that nutrient enrichment in the protected and non-protected areas was the greatest in December, followed by the non-protected area in August. In contrast, the August protected area had the lowest nutrient enrichment. Significant differences were found in the composition of the bacterial and archaeal communities in seawater and sediments from different regions. Among the coral symbiotic microorganisms, the main dominant species of zooxanthellae is the C1 subspecies (42.22-56.35%). The dominant phyla of bacteria were Proteobacteria, Cyanobacteria, Firmicutes, and Bacteroidota. Only in the August protected area did a large number (41.98%) of SAR324_cladeMarine_group_B exist. The August protected and non-protected areas and December protected and non-protected areas contained beneficial bacteria as biomarkers. They were Nisaea, Spiroplasma, Endozoicomonas, and Bacillus. No pathogenic bacteria appeared in the protected area in August. The dominant phylum in Archaea was Crenarchaeota. These symbiotic coral microorganisms' relative abundances and compositions vary with environmental changes. The enrichment of dissolved inorganic nitrogen in environmental media is a key factor affecting the composition of coral microbial communities. Co-occurrence analysis showed that nutrient enrichment under anthropogenic disturbances enhanced the interactions between coral symbiotic microorganisms. These findings improve our understanding of the adaptations of coral holobionts to various nutritional environments.

Effect of the consumption of brazzein and monellin, two recombinant sweet-tasting proteins, on rat gut microbiota.

Sweet-tasting proteins (SPs) are proteins of plant origin initially isolated from tropical fruits. They are thousands of times sweeter than sucrose and most artificial sweeteners. SPs are a class of proteins capable of causing a sweet taste sensation in humans when interacting with the T1R2/T1R3 receptor. SP thaumatin has already been introduced in the food industry in some countries. Other SPs, such as monellin and brazzein, are promising products. An important stage in researching SPs, in addition to confirming the absence of toxicity, mutagenicity, oncogenicity, and allergenic effects, is studying their influence on gut microbiota. In this paper we describe changes in the composition of rat gut microbiota after six months of consuming one of two recombinant SPs-brazzein or monellin. A full length 16S gene sequencing method was used for DNA library barcoding. The MaAsLin2 analysis results showed noticeable fluctuations in the relative abundances of Anaerocella delicata in brazzein-fed rat microbiota, and of Anaerutruncus rubiinfantis in monellin-fed rat microbiota, which, however, did not exceed the standard deviation. The sucrose-fed group was associated with an increase in the relative abundance of Faecalibaculum rodentium, which may contribute to obesity. Overall, prolonged consumption of the sweet proteins brazzein and monellin did not significantly change rat microbiota and did not result in the appearance of opportunistic microbiota. This provides additional evidence for the safety of these potential sweeteners.

Gut microbial communities and their potential roles in cellulose digestion and thermal adaptation of earthworms.

Adaptations to temperature and food resources, which can be affected by gut microbiota, are two main adaptive strategies allowing soil fauna to survive in their habitats, especially for cold-blooded animals. Earthworms are often referred to as ecosystem engineers because they make up the biggest component of the animal biomass found in the soil. They are considered as an important indicator in the triangle of soil quality, health and functions. However, the roles of gut microbiota in the environmental adaptation of earthworms at a large scale remain obscure. We explored the gut bacterial communities and their functions in the environmental adaptation of two widespread earthworm species (Eisenia nordenskioldi Eisen and Drawida ghilarovi Gates) in Northeast China (1661 km). Based on our findings, the alpha diversity of gut bacterial communities decreased with the increase of latitude, and the gut bacterial community composition was shaped by both mean annual temperature (MAT) and cellulose. Actinobacteria, Proteobacteria, Firmicutes, and Planctomycetes, recognized as the predominant cellulose degraders, were keystone taxa driving gut bacterial interactions. Actinobacteria, Firmicutes, and Planctomycetes were influenced by MAT and cellulose, and had higher contributions to gut total cellulase activity. The optimal temperature for total cellulase in the gut of E. nordenskioldi (25-30 °C) was lower than that of D ghilarovi (40 °C). The gut microbiota-deleted earthworms had the lowest cellulose degradation rate (1.07 %). The cellulose was degraded faster by gut bacteria from the host they were derived, indicating the presence of home field advantage of cellulose decomposition. This study provides a foundation for understanding the biotic strategies adopted by earthworms when they enter a new habitat, with gut microbiota being central to food digestion and environmental adaptability.

Genomic and AntiSMASH Analyses of Marine-Sponge-Derived Strain Aspergillus niger L14 Unveiling Its Vast Potential of Secondary Metabolites Biosynthesis.

Aspergillus niger is one of the most important sources of secondary metabolites (SMs), with a wide array of pharmacological effects, including anti-inflammatory, antitumor, immunomodulatory and antioxidant effects. However, the biosynthetic analysis of these bioactive components has been rarely reported owing to the lack of high-quality genome sequences and comprehensive analysis. In this study, the whole genome of one marine-sponge-derived strain A. niger L14 was sequenced and assembled as well as in-depth bioinformatic analysis. The results indicated that the sequence assembly of strain L14 generated one high-quality genome with a total size of 36.1 Mb, a G + C content of 45.3% and an N50 scaffold of 4.2 Mb. Gene annotation was extensively deployed using various BLAST databases, including non-redudant (Nr) protein sequence, nucleotide (Nt) sequence, Swiss-Prot, Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and Clusters of Orthologous Groups (COG) as well as Pathogen Host Interactions (PHI) and Carbohydrate-active enzymes (CAZy) databases. AntiSMASH analysis revealed that this marine strain harbors a total of 69 SMs biosynthesis gene clusters (BGCs), including 17 PKSs, 18 NRPSs, 21 NRPS-likes, 9 terpenes, 2 indoles, 1 betalactone and 1 siderophore, suggesting its biosynthetic potential to produce a wide variety of SMs. These findings will assist in future investigations on the genetic basis of strain L14 and provide insights into its new bioactive SMs for new drug discovery.

Symbiotic Microorganisms and Their Different Association Types in Aquatic and Semiaquatic Bugs.

True bugs (Hemiptera, suborder Heteroptera) constitute the largest suborder of nonholometabolous insects and occupy a wide range of habitats various from terrestrial to semiaquatic to aquatic niches. The transition and occupation of these diverse habitats impose various challenges to true bugs, including access to oxygen for the aquatic species and plant defense for the terrestrial phytophagans. Although numerous studies have demonstrated that microorganisms can provide multiple benefits to terrestrial host insects, a systematic study with comprehensive higher taxa sampling that represents aquatic and semiaquatic habitats is still lacking. To explore the role of symbiotic microorganisms in true bug adaptations, 204 samples belonging to all seven infraorders of Heteroptera were investigated, representing approximately 85% of its superfamilies and almost all known habitats. The symbiotic microbial communities of these insects were analyzed based on the full-length amplicons of the bacterial 16S rRNA gene and fungal ITS region. Bacterial communities varied among hosts inhabiting terrestrial, semiaquatic, and aquatic habitats, while fungal communities were more related to the geographical distribution of the hosts. Interestingly, co-occurrence networks showed that species inhabiting similar habitats shared symbiotic microorganism association types. Moreover, functional prediction analyses showed that the symbiotic bacterial community of aquatic species displayed richer amino acid and lipid metabolism pathways, while plant-feeding true bugs benefited more from the symbiont-provided xenobiotics biodegradation pathway. These results deepened the recognition that symbiotic microorganisms were likely to help heteropterans occupy diverse ecological habitats and provided a reference framework for further studies on how microorganisms affect host insects living in various habitats. IMPORTANCE Symbiotic bacteria and fungi generally colonize insects and provide various benefits for hosts. Although numerous studies have investigated symbionts in terrestrial plant-feeding insects, explorations of symbiotic bacterial and fungal communities in aquatic and semiaquatic insects are rare. In this study, the symbiotic microorganisms of 204 aquatic, semiaquatic, and terrestrial true bugs were explored. This comprehensive taxon sampling covers ~85% of the superfamilies of true bugs and most insect habitats. Analyses of the diversity of symbionts demonstrated that the symbiotic microbial diversities of true bugs were mainly affected by host habitats. Co-occurrence networks showed that true bugs inhabiting similar habitats shared symbiotic microbial association types. These correlations between symbionts and hosts together with the functions of bacterial communities indicated that symbiotic microbial communities may help true bugs adapt to (semi)aquatic habitats.

An Overview of Bioactive 1,3-Oxazole-Containing Alkaloids from Marine Organisms.

1,3-Oxazole chemicals are a unique class of five-membered monocyclic heteroarenes, containing a nitrogen atom and an oxygen. These alkaloids have attracted extensive attention from medicinal chemists and pharmacologists owing to their diverse arrays of chemical structures and biological activities, and a series of 1,3-oxazole derivatives has been developed into therapeutic agents (e.g., almoxatone, befloxatone, cabotegravir, delpazolid, fenpipalone, haloxazolam, inavolisib). A growing amount of evidence indicates that marine organisms are one of important sources of 1,3-oxazole-containing alkaloids. To improve our knowledge regarding these marine-derived substances, as many as 285 compounds are summarized in this review, which, for the first time, highlights their sources, structural features and biological properties, as well as their biosynthesis and chemical synthesis. Perspective for the future discovery of new 1,3-oxazole compounds from marine organisms is also provided.

Chemical constituents of liquid culture of symbiotic Chaetomium globosum ML-4 of oyster and their in vitro antitumor activity / 中国中药杂志

Isolation and purification of chemical constituents of liquid culture of symbiotic Chaetomium globosum ML-4 of oyster was performed through silica gel column chromatography, gel filtration over Sephadex LH-20, preparative TLC and HPLC. Five compounds were obtained and their structures were determined as chaetoglobosin V(1), chaetoglobosin Vb(2), tyrosol(3), 5-methyluracil(4)and uracil(5), respectively, based on HR-MS and NMR data and comparison with literatures. In vitro cytotoxicity of compounds against human hepatocellular carcinoma cell line SMMC-7721 were measured byMTT method, and results showed that compound 1 could obviously inhibit the proliferation of SMMC-7721 cells with an IC₅₀ value of 60.5 mg•L⁻¹, while the IC₅₀ value of positive control cisplatin was 19.96 mg•L⁻¹. Further studies discovered that compound 1 could lead to G2 phase arrest in SMMC-7721 cells and induce SMMC-7721 cells apoptosis. The ratio of Bcl-2/Bax in SMMC-7721 cells was decreased. The expression of protein Caspases-3,-8,-9 was improved and the expression and phosphorylation level of Akt were reduced. Aforementioned results revealed that in vitro antitumor activity of compound 1 against SMMC-7721 cells were related to G2 phase cell cycle arrest and induced-apoptosis. The induced-apoptosis was involved in both the mitochondrial pathway and the death receptor pathway and connected with activity decline of PI3K/Akt signaling pathway.