Dynamics and diversity of symbiotic bacteria in Apolygus lucorum at different developmental stages

Background Apolygus lucorum is a worldwide omnivorous pest damaging a range of crops and causing great economic losses.Symbiotic bacteria living in insects play a key role in the nutrition,physiology,and behavior of hosts.Here,we present an experiment using Illumina HiSeq sequencing targeting the V3–V4 regions of bacteria’s 16S rRNA throughout the entire life cycle of A.lucorum.Results The first and second instar nymphs have the largest alpha diversity compared with other life stages of the insect.Bacterial phyla Proteobacteria(72.29%),Firmicutes(15.24%),Actinobacteria(7.76%)exhibit the largest relative abundance in all developmental stages.Erwinia(23.97%)and Lactococcus(10.62%)are the two genera with the high-est relative abundance.The relative abundance of Erwinia in the nymph stage is significantly greater than the adult stage,and the relative abundance of Lactococcus in 6-day-old and 9-day-old adult females is higher compared with adult males.Conclusions These results reveal that microbial community composition and relative abundance shift dynamically at different life stages,implying that different bacterial phyla and genera may have specific roles in specific life stages such as metabolism,nutrition absorption,detoxification,and reproduction.This study reveals for the first time the community composition and ecological dynamics of symbiotic bacteria throughout the life stages of A.lucorum,and thus may provide insight to new strategies for pest control.

Living symbiotic bacteria-involved skin dressing to combat indigenous pathogens for microbiome-based biotherapy toward atopic dermatitis

Many skin diseases,such as atopic dermatitis(AD),are featured with the dysbiosis of skin microbiota.The clinically recommended options for AD treatments suffer from poor outcomes and high side-effects,leading to severe quality-of-life impairment.To deal with this long-term challenge,we develop a living bacterial formu-lation(Hy@Rm)that integrates skin symbiotic bacteria of Roseomonas mucosa with poly(vinyl pyrrolidone),poly(vinyl alcohol)and sodium alginate into a skin dressing by virtue of the Ca^(2+)-mediated cross-linking and the freezing-thawing(F-T)cycle method.Hy@Rm dressing creates a favorable condition to not only serve as extrinsic culture harbors but also as nutrient suppliers to support R.mucosa survival in the harsh microenvi-ronment of AD sites to defeat S.aureus,which predominantly colonizes AD skins as an indigenous pathogen,mainly through the secretion of sphingolipids metabolites by R.mucosa like a therapeutics bio-factory.Mean-while,this elaborately designed skin dressing could accelerate wound healing,normalize aberrant skin char-acters,recover skin barrier functions,alleviate AD-associated immune/inflammation responses,functioning like a combinational therapy.This study offers a promising means for the topical bacteria transplant to realize effective microbe biotherapy toward the skin diseases feature with microbe milieu disorders,including but not limited to AD disease.

Population genetic structure of Sitobion miscanthi in China

The wheat aphid, Sitobion miscanthi, is one of the most destructive pests of wheat plants in the temperate regions of China. Little is known about the genetic structure evolution of the different geographic populations of S. miscanthi with its migration. In this study, we investigated the population genetic structure and demographic history of S. miscanthi by analysing 18 geographical populations across China using one mitochondrial gene, COI;one nuclear gene, EF-1α;and two endosymbiont Buchnera genes, gnd and trpA. Analysis of data from the various groups showed high haplotype diversity and low nucleotide variation. SAMOVA analysis did not find a correlation between genetic distance and geographic distance. However, areas with high population diversity exhibited high haplotype diversity. Therefore, we speculate that there are two main natural migration pathways of S. miscanthi in China. One is from Yunnan to the Sichuan Basin, and the other is from Wuhan, Xinyang and Jiaodong Peninsula areas to the northwest. Based on this hypothesis, we inferred that these aphid populations appear first in the southwestern and southern regions and spread to the north with the help of the southeastern and southwestern monsoons, which occur in spring and summer. In autumn, the aphids spread southward with the northeastern and northwestern monsoons.

Diversity of bacteria in different life stages and their impact on the development and reproduction of Zeugodacus tau(Diptera:Tephritidae)

Fruit flies usually harbor diverse communities of bacteria in their digestive systems,which are known to play a significant role in their fitness.However,little information is available on Zeugodacus tau,a polyphagous pest worldwide.This study reports the first extensive analysis of bacterial communities in different life stages and their effect on the development and reproduction of laboratory-reared Z tan.Cultured bacteria were identified using the conventional method and all bacteria were identified by highthroughput technologies(16S ribosomal RNA gene sequencing of V3-V4 region).A total of six bacterial phyla were identified in larvae,pupae,and male and female adult flies,which were distributed into 14 classes,32 orders,58 families and 96 genera.Proteobacteria was the most represented phylum in all the stages except larvae.Enterobacter,Klebsiella,Providencia,and Pseudomonas were identified by conventional and next-generation sequencing analysis in both male and female adult flies,and Enterobacter was found to be the main genus.After being fed with antibiotics from the first instar larvae,bacterial diversity changed markedly in the adult stage.Untreated flies laid eggs and needed 20 days before oviposition while the treated flies showed ovary development inhibited and were not able to lay eggs,probably due to the alteration of the microbiota.These findings provide the cornerstone for unexplored research on bacterial function in Z tau,which will help to develop an environmentally friendly management technique for this kind of harmful insect.

A new bacteria-free strategy induced by MaGal2 facilitates pinewood nematode escape immune response from its vector beetle

Symbiotic microbes play a crucial role in regulating parasite–host interactions;however,the role of bacterial associates in parasite–host interactions requires elucidation.In this study,we showed that,instead of introducing numerous symbiotic bacteria,dispersal of 4th-stage juvenile(JIV)pinewood nematodes(PWNs),Bursaphelenchus xylophilus,only introduced few bacteria to its vector beetle,Monochamus alternatus(Ma).JIV showed weak binding ability to five dominant bacteria species isolated from the beetles’pupal chamber.This was especially the case for binding to the opportunistic pathogenic species Serratia marcescens;the nematodes’bacteria binding ability at this critical stage when it infiltrates Ma for dispersal was much weaker compared with Caenorhabditis elegans,Diplogasteroides asiaticus,and propagative-stage PWN.The associated bacterium S.marcescens,which was isolated from the beetles’pupal chambers,was unfavorable to Ma,because it caused a higher mortality rate upon injection into tracheae.In addition,S.marcescens in the tracheae caused more immune effector disorders compared with PWN alone.Ma_Galectin2(MaGal2),a pattern-recognition receptor,was up-regulated following PWN loading.Recombinant MaGal2 protein formed aggregates with five dominant associated bacteria in vitro.Moreover,MaGal2 knockdown beetles had up-regulated prophenoloxidase gene expression,increased phenoloxidase activity,and decreased PWN loading.Our study revealed a previously unknown strategy for immune evasion of this plant pathogen inside its vector,and provides novel insights into the role of bacteria in parasite–host interactions.

Cradle for the newborn Monochamus saltuarius:Microbial associates to ward off entomopathogens and disarm plant defense

The Japanese pine sawyer,Monochamus saltuarius,as a beetle vector of Bur-saphelenchus xylophilus(pine wood nematode),is an economically important forest pest in Eurasia.To feed on the phloem and xylem of conifers,M.saltuarius needs to overcome various stress factors,including coping with entomopathogenic bacteria and also various plant secondary compounds(PSCs).As an important adaptation strategy to colonize host trees,M.saltuarius deposit eggs in oviposition pits to shield their progeny.These pits har-bor bacterial communities that are involved in the host adaptation of M.saltuarius to the conifers.However,the composition,origin,and functions of these oviposition pit bacteria are rarely understood.In this study,we investigated the bacterial community associated with M.saltuarius oviposition pits and their ability to degrade PSCs.Results showed that the bacterial community structure of M.saltuarius oviposition pits significantly differed from that of uninfected phloem.Also,the oviposition pit bacteria were predicted to be enriched in PSC degradation pathways.The microbial community also harbored a lethal strain of Serratia,which was significantly inhibited.Meanwhile,metatranscriptome anal-ysis indicated that genes involved in PSCs degradation were expressed complementarily among the microbial communities of oviposition pits and secretions.In vitro degrada-tion showed that bacteria cultured from oviposition pits degraded more monoterpenes and flavonoids than bacteria cultured from uninfected phloem isolates.Disinfection of ovipo-sition pits increased the mortality of newly hatched larvae and resulted in a significant decrease in body weight in the early stages.Overall,our results reveal that M.saltuarius construct oviposition pits that harbor a diverse microbial community,with stronger PSCs degradation abilities and a low abundance of entomopathogenic bacteria,resulting in the increased fitness of newly hatched larvae.

Gut bacterium promotes host fitness in special ecological niche by affecting sugar metabolism in Drosophila suzukii

As an important fruit pest of global significance,Drosophila suzukii occupies a special ecological niche,with the characteristics of high sugar and low protein contents.This niche differs from those occupied by other fruit-damaging Drosophila species.Gut bacteria substantially impact the physiology and ecology of insects.However,the contribution of gut microbes to the fitness of D.suzukii in their special ecological niche remains unclear.In this study,the effect of Klebsiella oxytoca on the development of D.suzukii was examined at physiological and molecular levels.The results showed that,after the removal of gut microbiota,the survival rate and longevity of axenic D.suzukii decreased significantly.Reintroduction of K.oxytoca to the midgut of D.suzukii advanced the development level of D.suzukii.The differentially expressed genes and metabolites between axenic and K.oxytoca-reintroduced D.suzukii were enriched in the pathways of carbohydrate metabolism.This advancement was achieved through an increased glycolysis rate and the regulation of the transcript level of key genes in the glycolysis/gluconeogenesis pathway.Klebsiella oxytoca is likely to play an important role in increasing host fitness in their high-sugar ecological niche by stimulating the glycolysis/gluconeogenesis pathway.As a protein source,bacteria can also provide direct nutrition for D.suzukii,which depends on the quantity or biomass of K.oxytoca.This result may provide a new target for controlling D.suzukii by inhibiting sugar metabolism through eliminating the effect of K.oxytoca and thus disrupting the balance of gut microbial communities.

An overview of probiotic health booster-kombucha tea

Traditional herbal medicine(THM)is a significant division of traditional Chinese medicine(TCM)that plays an important role in maintaining health and disease prevention.WHO has consistently highlighted the significance of traditional,complementary,and alternative medicine in human healthcare.Most people in Eastern Asia will start their day with a cup of tea.The tea provides a nourishing effect,and it has become an inevitable part of life.There are several types of tea,like black tea,green tea,oolong tea,white tea,and herbal tea.Besides the refreshments,it is important to consume beverages that benefit health.One such alternative is a healthy probiotic drink called kombucha,a fermented tea.Kombucha tea is aerobically fermented by infusing sweetened tea with a cellulose mat/pellicle called SCOBY(symbiotic culture of bacteria and yeast).Kombucha is a source of bioactive compounds that include organic acids and amino acids,vitamins,probiotics,sugars,polyphenols,and antioxidants.Currently,studies on kombucha tea and SCOBY are gaining attention for their remarkable properties and applications in the food and health industries.The review gives an overview of the production,fermentation,microbial diversity,and metabolic products of kombucha.The possible implications for human health are also discussed.

Metabolic relationships between marine red algae and algae‑associated bacteria

Mutualistic interactions between marine phototrophs and associated bacteria are an important strategy for their success-ful survival in the ocean,but little is known about their metabolic relationships.Here,bacterial communities in the algal sphere(AS)and bulk solution(BS)of nine marine red algal cultures were analyzed,and Roseibium and Phycisphaera were identified significantly more abundantly in AS than in BS.The metabolic features of Roseibium RMAR6-6(isolated and genome-sequenced),Phycisphaera MAG 12(obtained by metagenomic sequencing),and a marine red alga,Porphyridium purpureum CCMP1328(from GenBank),were analyzed bioinformatically.RMAR6-6 has the genetic capability to fix nitrogen and produce B vitamins(B1,B2,B5,B6,B9,and B12),bacterioferritin,dimethylsulfoniopropionate(DMSP),and phenylacetate that may enhance algal growth,whereas MAG 12 may have a limited metabolic capability,not producing vitamins B9 and B12,DMSP,phenylacetate,and siderophores,but with the ability to produce bacitracin,possibly modulating algal microbiome.P.purpureum CCMP1328 lacks the genetic capability to fix nitrogen and produce vitamin B12,DMSP,phenylacetate,and siderophore.It was shown that the nitrogen-fixing ability of RMAR6-6 promoted the growth of P.pur-pureum,and DMSP reduced the oxidative stress of P.purpureum.The metabolic interactions between strain RMAR6-6 and P.purpureum CCMP1328 were also investigated by the transcriptomic analyses of their monoculture and co-culture.Taken together,potential metabolic relationships between Roseibium and P.purpureum were proposed.This study provides a bet-ter understanding of the metabolic relationships between marine algae and algae-associated bacteria for successful growth.

Effects of a combined infection with Paranosema locustae and Beauveria bassiana on Locusta migratoria and its gut microflora

Even though Paranosema locustae is widely used in China as a biological agent for controlling grasshoppers,the mortality rate is initially quite low.This study sought to determine whether the simultaneous use of P.locustae and Beauveria bassiana would be a more effective control strategy.Additionally,changes in the intestinal microbial communities of migratory locusts infected with the two pathogens were analyzed to investigate the roles of gut microbes in pathogen-host interactions.The mortality rate of locusts inoculated with B.bassiana and P.locustae simultaneously was not significantly higher than expected but the mortality rates of locusts inoculated with B.bassiana 3,6,and 9 days after inoculation with P.locustae were significantly higher than if their effects were additive,indicating synergism.A MiSeq analysis found that Weissella was the most common bacterium,representing 41.48%and 51.62%of the total bacteria in the mid-and hindguts,respectively,and the bacterial declines were greatest during dual infections with B.bassiana and P.locustae.The appropriately timed combined application of P.locustae and B.bassiana was more effective against locusts than either treatment alone.Moreover,the combined inoculation of the two pathogens changed the gut microflora of locusts,indicating the potential relevancy of their synergistic effects on locust control.