Molecular phylogenetic profiling of gut‐associated bacteria in larvae and adults of flesh flies

Flesh flies of the genus Sarcophaga (Diptera: Sarcophagidae) are carrion‐breeding, necrophagous insects important in medical and veterinary entomology as potential transmitters of pathogens to humans and animals. Our aim was to analyse the diversity of gut‐associated bacteria in wild‐caught larvae and adult flesh flies using culture‐dependent and culture‐independent methods. Analysis of 16S rRNA gene sequences from cultured isolates and clone libraries revealed bacteria affiliated to Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes in the guts of larval and adult flesh flies. Bacteria cultured from larval and adult flesh fly guts belonged to the genera Acinetobacter, Bacillus, Budvicia, Citrobacter, Dermacoccus, Enterococcus, Ignatzschineria, Lysinibacillus, Myroides, Pasteurella, Proteus, Providencia and Staphylococcus. Phylogenetic analysis showed clone sequences of the genera Aeromonas, Bacillus, Bradyrhizobium, Citrobacter, Clostridium, Corynebacterium, Ignatzschineria, Klebsiella, Pantoea, Propionibacterium, Proteus, Providencia, Serratia, Sporosarcina, Weissella and Wohlfahrtiimonas. Species of clinically significant genera such as Ignatzschineria and Wohlfahrtiimonas spp. were detected in both larvae and adult flesh flies. Sequence analysis of 16S rRNA gene libraries supported culture‐based results and revealed the presence of additional bacterial taxa. This study determined the diversity of gut microbiota in flesh flies, which will bolster the ability to assess microbiological risk associated with the presence of these flies. The present data thereby establish a platform for a much larger study.     

Gut microbiota in the burying beetle,Nicrophorus vespilloides,provide colonization resistance against larval bacterial pathogens

Carrion beetles, Nicrophorus vespilloides, are reared on decomposing carrion where larvae are exposed to high populations of carcass‐derived bacteria. Larvae do not become colonized with these bacteria but instead are colonized with the gut microbiome of their parents, suggesting that bacteria in the beetle microbiome outcompete the carcass‐derived species for larval colonization. Here, we test this hypothesis and quantify the fitness consequences of colonization with different bacterial symbionts. First, we show that beetles colonized by their endogenous microbiome produce heavier broods than those colonized with carcass‐bacteria. Next, we show that bacteria from the endogenous microbiome, including Providencia rettgeri and Morganella morganii, are better colonizers of the beetle gut and can outcompete nonendogenous species, including Serratia marcescens and Escherichia coli, during in vivo competition. Finally, we find that Providencia and Morganella provide beetles with colonization resistance against Serratia and thereby reduce Serratia‐induced larval mortality. This effect is eliminated in larvae first colonized by Serratia, suggesting that while competition within the larval gut is determined by priority effects, these effects are less important for Serratia‐induced mortality. Our work suggests that an unappreciated benefit of parental care in N. vespilloides is the social transmission of the microbiome from parents to offspring.     

Dynamics of the intestinal bacterial community in black soldier fly larval guts and its influence on insect growth and development

Black soldier fly (BSF), Hermetia illucens (Diptera: Stratiomyidae), is a prominent insect for the bioconversion of various organic wastes. As a saprotrophic insect, the BSF inhabits microbe-rich environments. However, the influences of the intestinal microorganisms on BSF growth and development are not very clear. In this study, the dynamics of the intestinal bacterial community of BSF larvae (BSFL) were analyzed using pyrosequencing. Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria were the most prevalent bacterial phyla in the intestines of all larval instars. The dynamic changes in bacterial community compositions among different larval instars were striking at the genus level. Klebsiella, Clostridium, Providencia, and Dysgonomonas were the relatively most abundant bacteria in the 1st- to 4th-instar BSFL, respectively. Dysgonomonas and Providencia also dominated the 5th- and 6th-instar larvae, at ratios of 31.1% and 47.2%, respectively. In total, 148 bacterial strains affiliated with 20 genera were isolated on different media under aerobic and anaerobic conditions. Among them, 6 bacteria, BSF1–BSF6, were selected for further study. The inoculation of the 6 isolates independently into germ-free BSFL feeding on an artificial diet showed that all the bacteria, except BSF4, significantly promoted BSF growth and development compared with the germ-free control. Citrobacter, Dysgonomonas, Klebsiella, Ochrobactrum, and Providencia promoted BSF development significantly by increasing the weight gains of larvae and pupae, as well as increasing the prepupae and eclosion rates. In addition, Citrobacter, Klebsiella and Providencia shortened the BSF life cycle significantly. The results illustrate the promotive effects of intestinal bacteria on BSF growth and development.     

The effect of bacterially‐dense environments on the development and immune defences of the blowfly Lucilia sericata

Competitive interactions between insects and microbes and the associated cost of development in bacterially‐dense environments are investigated using the blowfly Lucilia sericata (Meigen) (Diptera: Calliphoridae) as a model. The effects of developing in a bacterially‐dense environment are measured by assessing the fitness consequences of competition using the pathogen Staphylococcus aureus. Fitness is quantified in terms of larval survival, puparial development and adult emergence.The influence of bacteria on larval immune defences is investigated using optical density to assess whether antibacterial potency of the larval excretion/secretion changes in response to the degree of contamination of the larval environment. The results obtained demonstrate that bacterial presence has no detrimental effect on survival of L. sericata from egg to adult eclosion, or on puparial size. Additionally, the level of microbial contamination of larvae has no effect on the antibacterial potency of the larval excretion/secretion. These findings confirm that larval antibacterial activity is not induced by the presence of environmental bacteria but is produced constitutively.     

A metagenomic assessment of the bacteria associated with <Emphasis Type="Italic">Lucilia sericata</Emphasis> and <Emphasis Type="Italic">Lucilia cuprina</Emphasis> (<Emphasis Type="Italic">Diptera: Calliphoridae</Emphasis>)

Lucilia Robineau-Desvoidy (Diptera: Calliphoridae) is a blow fly genus of forensic, medical, veterinary, and agricultural importance. This genus is also famous because of its beneficial uses in maggot debridement therapy (MDT). Although the genus is of considerable economic importance, our knowledge about microbes associated with these flies and how these bacteria are horizontally and trans-generationally transmitted is limited. In this study, we characterized bacteria associated with different life stages of Lucilia sericata (Meigen) and Lucilia cuprina (Wiedemann) and in the salivary gland of L. sericata by using 16S rDNA 454 pyrosequencing. Bacteria associated with the salivary gland of L. sericata were also characterized using light and transmission electron microscopy (TEM). Results from this study suggest that the majority of bacteria associated with these flies belong to phyla Proteobacteria, Firmicutes, and Bacteroidetes, and most bacteria are maintained intragenerationally, with a considerable degree of turnover from generation to generation. In both species, second-generation eggs exhibited the highest bacterial phylum diversity (20 % genetic distance) than other life stages. The Lucilia sister species shared the majority of their classified genera. Of the shared bacterial genera, Providencia, Ignatzschineria, Lactobacillus, Lactococcus, Vagococcus, Morganella, and Myroides were present at relatively high abundances. Lactobacillus, Proteus, Diaphorobacter, and Morganella were the dominant bacterial genera associated with a survey of the salivary gland of L. sericata. TEM analysis showed a sparse distribution of both Gram-positive and Gram-negative bacteria in the salivary gland of L. sericata. There was more evidence for horizontal transmission of bacteria than there was for trans-generational inheritance. Several pathogenic genera were either amplified or reduced by the larval feeding on decomposing liver as a resource. Overall, this study provides information on bacterial communities associated with different life stages of Lucilia and their horizontal and trans-generational transmission, which may help in the development of better vector-borne disease management and MDT methods.     

Rearing bacteria and maggots concurrently: a protocol using Lucilia sericata (Diptera: Calliphoridae) as a model species

Maggot debridement therapy using live Lucilia sericata (Meigen) larvae is an efficient and cost-effective way to treat chronic wounds. The recent increase in studies to assess the antibacterial properties of L. sericata has created a need for a simple, low-cost, and comprehensible rearing and investigative method for researchers with little or no entomological experience. This paper describes and evaluates a reproducible protocol for sterilising and rearing blowfly larvae utilising two sterile artificial diets (blood–yeast agar and pre-prepared blood agar plates) that is suitable for directly investigating the effect of larvae on microbial growth. Using Lucilia sericata as a model, the results show that larval growth on the pre-prepared blood agar diet is detrimental to larval growth and survival, whereas larval growth and survival on the blood–yeast agar diet are comparable to those of larvae raised on porcine liver. This diet is proposed as a standard for blowfly and bacteria interaction studies investigating clinical microbial strains. Developmental data are provided for L. sericata larvae raised on both sterile and nonsterile diets so that researchers can determine the effect of treatment based on the length of time for larvae to reach the required life stage at 25 ± 2 °C. Information on larval ageing (instars at an average of 1, 2, 3 and 4 days), oviposition times (4–5 days after adult emergence) and adult longevity on the diets (102–116 days) is also given.     

Manipulation of insect gut microbiota towards the improvement of Bactrocera oleae artificial rearing

Bactrocera oleae (Rossi) (Diptera: Tephritidae) is the main pest of olive trees (Olea europaea L.), causing major damages in olive crops. Improvement of mass rearing is a prerequisite for the successful development of large-scale sterile insect technique (SIT) applications. This can be achieved through the enrichment of artificial diets with gut bacteria isolates. We assessed the efficiency of three gut bacteria previously isolated from Ceratitis capitata (Wiedemann), and four isolated from B. oleae, as larval diet additives in both live and inactivated/dead forms. Our results showed that dead Enterobacter sp. AA26 increased pupal weight, whereas both live and dead cells increased pupal and adult production and reduced immature developmental time, indicating that its bacterial cells serve as a direct nutrient source. Live Providencia sp. AA31 improved pupal and adult production, enhanced male survival under stress conditions, and delayed immature development. Dead Providencia sp. AA31, however, did not affect production rates, indicating that live bacteria can colonize the insect gut and biosynthesize nutrients essential for larval development. Live and dead Bacillus sp. 139 increased pupal weight, accelerated immature development, and increased adult survival under stress. Moreover, live Bacillus sp. 139 improved adult production, indicating that Bacillus cells are a direct source of nutrients. Dead Serratia sp. 49 increased pupal and adult production and decreased male survival under stress conditions whereas live cells decreased insect production, indicating that the live strain is entomopathogenic, but its dead cells can be utilized as nutrient source. Klebsiella oxytoca, Enterobacter sp. 23, and Providencia sp. 22 decreased pupal and subsequent adult production and were harmful for B. oleae. Our findings indicate that dead Enterobacter sp. AA26 is the most promising bacterial isolate for the improvement of B. oleae mass rearing in support of future SIT or related population suppression programs.     

Bacteria Isolated from the Different Developmental Stages and Larval Organs of the Obligate Parasitic Fly, Wohlfahrtia magnifica (Diptera: Sarcophagidae)

Wohlfahrtia magnifica (Diptera: Sarcophagidae) is the major myiasis-causing fly species in the whole of Eurasia for most important domestic animals. The aim of the present work was to obtain data on the culturable bacteria isolated under aerobic conditions from this fly: bacteria were isolated from all developmental stages (larvae, pupa, and imago) of Wohlfahrtia magnifica, and the third-stage larval organs were also sampled. To determine the possible antagonistic effects between the dominant bacterial groups, an antibiosis assay was carried out. Plating and isolation of bacteria was performed by classical microbiological methods. Characterization of the isolated strains was carried out via a polyphasic approach; classical phenotypic tests, chemotaxonomical examinations, and 16S rDNA sequence analyses were also applied. In the case of maggot macerate samples, members of the family Enterobacteriaceae were characteristic. Members of a new genus (Schineria) belonging to the γ subdivision of proteobacteria were also isolated. According to our data, the shifts in the Schineria and Proteus populations within the larvae are strongly influenced by their interactions with each other and among the members of the family Enterobacteriaceae. The pupa and imago samples contained several other Gram-negative bacteria (Stenotrophomonas, Brevundimonas, etc.). Among Gram-positive bacteria, in all maggot macerate samples, members of the genus Bacillus and the Arthrobacter–Micrococcus group of actinobacteria were dominant (neither of them was a producer or sensitive to the compounds of other microorganisms), and bacteria related to the genus Corynebacterium were also found. From the larvae Aureobacterium liquefaciens and Enterococcus faecalis were isolated, and from the pupae Dietzia maris and Enterococcus faecalis. In the samples of third-stage larval organs, the dominant groups were the same as in the third-stage larval macerate sample; however, several additional genera/species were observed (Rhodococcus fascians, Streptomyces sp., Rathayibacter sp., Bacillus thuringiensis/cereus).     

To eat or get heat: Behavioral trade‐offs between thermoregulation and feeding in gregarious necrophagous larvae

The thermoregulation behavior of Lucilia sericata larvae (Diptera: Calliphoridae), a necrophagous species that feeds on vertebrate cadavers, was investigated. These larvae require high heat incomes to develop, and can elevate temperatures by forming large aggregates. We hypothesized that L. sericata larvae should continue to feed at temperatures up to 38 °C, which can be reached inside larval masses. Thermal regulation behavior such as movement between a hot food spot and colder areas was also postulated. The hypotheses were tested by tracking for 1 h the activity of single, starved third instar larvae in a Petri dish containing 1 food spot (FS) that was heated to a constant temperature of 25 °C, 34 °C or 38 °C with an ambient temperature of 25 °C. The influence of previous conspecific activity in the food on larval behavior was also tested. The crops of larvae were dissected to monitor food content in the digestive systems. Based on relative crop measurements, larvae fed at all food temperatures, but temperature strongly affected larval behavior and kinematics. The total time spent by larvae in FS and the duration of each stay decreased at high FS temperature. Previous activity of conspecifics in the food slightly increased the time spent by larvae in FS and also decreased the average distance to FS. Therefore, necrophagous L. sericata larvae likely thermoregulate during normal feeding activities by adjusting to local fluctuations in temperature, particularly inside maggot masses. By maintaining a steady internal body temperature, larvae likely reduce their development time.     

The antibacterial potency of the medicinal maggot, Lucilia sericata (Meigen): Variation in laboratory evaluation

Research to quantify the potency of larval excretion/secretion from Lucilia sericata using liquid culture assays has produced contradictory results. In this study, viable counting was used to investigate the effectiveness of excretion/secretion against three marker bacterial species (Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli) and the effects of varying growing conditions in assays. Results demonstrate that factors such as number of larvae, species of bacteria and addition of nutrient influence its antibacterial potency. Therefore a standardised method should be employed for liquid culture assays when investigating the antibacterial activity of larval excretion/secretion from L. sericata.     

基于宏基因组测序技术揭示大泷六线鱼肠道微生物特征北大核心

对大泷六线鱼不同生长期肠道微生物进行分析。【目的】基于宏基因组学技术揭示其肠道微生物变化特征及其与营养的联系。【方法】对大泷六线鱼仔鱼、稚鱼和幼鱼肠道微生物样本进行HiSeq高通量测序,分析菌群结构,比较微生物群落的多样性,探究生长过程中肠道微生物的相互演替及功能关系。【结果】门水平上,鱼肠道微生物在生长过程中优势菌门变形菌门(Proteobacteria)递减,而厚壁菌门(Firmcutes)递增;属水平上,仔鱼期的弧菌属(Vibrio)(37.8%)、稚鱼期的发光杆菌属(Photobacterium)(77.8%)、幼鱼期的乳酸菌属(Lactococcus)(42.5%)占优势,微生物群落组成发生显著变化;且仔鱼期的多样性高,幼鱼期的丰富度高;物种差异也呈现着与生长特征的相关性,幼鱼期差异标志物是厚壁菌门、芽孢杆菌纲(Bacilli)、乳酸杆菌目(Lactobacillales)、链球菌科(Streptococcaceae)、乳球菌属(Lactococcus)和乳酸乳球菌(Lactococcus lactis);稚鱼期差异标志物是发光菌属、托鲁尼发光菌(Photobacterium toruni);仔鱼期差异标志物是Phaeobacter inhibens、Colwellia aestuarii和Colwellia polaris等。宏基因组功能水平分析显示,KEGG数据统计代谢功能占优势,随生长呈现递增趋势,鱼肠道微生物群在碳水化合物代谢、氨基酸代谢、核苷酸代谢、能量代谢,以及辅助因子和维生素代谢中起着重要作用;从蛋白注释功能上也呈现了类似的结果,碳水化合物代谢(3350)和氨基酸代谢(2424)占代谢通路主要组成部分。功能差异分析表明,随着生长变化,微生物功能逐渐适应机体和环境需求,稚鱼期差异主要体现在能量代谢和糖降解功能;仔鱼期差异显著的是细胞的生长、死亡和凋亡功能,主要体现在光合作用方面;幼鱼期主要体现是二级代谢物的生物合成,其次是糖酵解和糖异生等碳水化合物代谢等。【结论】大泷六线鱼仔、稚、幼不同生长期肠道微生物结构存在显著差异,生长发育改变肠道微生物菌群的功能,采用差异物种和差异功能综合判定生长所需的营养,有助于提高养殖效益,为绿色健康生态养殖提供理论基础。     

Enterotoxigenic Bacteria in Food and Water from an Ethiopian Community

Food and water samples from an Ethiopian community were screened for the presence of enterotoxin-producing bacteria. Using the Chinese hamster ovary cell assay, 40 of 213 isolates (18.8%) produced heat-labile (LT) enterotoxin. These LT-producing isolates comprised 33 of 177 (18.6%) strains from 24 of 68 food samples (35.3%) and 7 of 36 (19.4%) isolates of 4 of 17 water samples (23.5%). One LT-producing strain each of Salmonella emek and of Shigella dysenteriae was found. Three pseudomonads, all LT producers, produced heat-stable enterotoxin as gauged by the suckling mouse test. Two strains of LT-enterotoxigenic Escherichia coli O68 were found in water samples. No enterotoxigenic E. coli were isolated from food samples, but 13 of the LT-producing strains were Enterobacter, Klebsiella, Serratia, and Proteus species, and 7 food samples yielded more than one species of enterotoxigenic bacterium. Of the enterotoxigenic isolates from food, 15 were oxidase-positive strains of the genera Aeromonas, Pseudomonas, Achromobacter, Flavobacterium, and Vibrio. LT-enterotoxigenic Enterobacter, Acinetobacter, Klebsiella, Proteus, Providencia, and Serratia species represented 20 of the food and water isolates. Culture supernatant fluids of representative strains of oxidase-positive and oxidase-negative species giving positive reactions in Chinese hamster ovary cell tests induced fluid accumulation in rabbit ileal loops. Eight of the food samples and two of the water samples contained more than one isolate or species of enterotoxigenic bacterium. The stability of the LT production by oxidase-positive bacteria and non-E. coli strains was assessed by the rabbit skin and adrenal cell tests after 9 months and 1 year of storage, respectively, in Trypticase soy broth with glycerol at −70°C. Only 33% of the oxidase-positive strains were still LT enterotoxigenic. Of the oxidase-negative strains, 50 and 33% were LT producing at 9 months and 1 year, respectively. None of the E. coli isolates, both enterotoxigenic and nonenterotoxigenic, possessed K88, K99, or colonization factor antigen. The survey demonstrates the presence in food and water of enterotoxigenic bacteria of the same species as those isolated from cases of infantile diarrhea in the same community, although a correlation between these sources and infantile diarrhea remains to be established.     

Application of Two‐Way Hierarchical Cluster Analysis for the Identification of Similarities between the Individual Lipid Fractions of Lucilia sericata

The composition of the cuticular and internal lipids of larvae and pupae of Lucilia sericata was studied using chromatographic techniques. The lipids from both stages of L. sericata had similar free fatty acid (FFA) profiles and also contained alcohols and cholesterol. The range of the number of C‐atoms detected for these classes of compounds was to some extent similar in larvae and pupae, but the relative amounts of each class differed between stages. Saturated as well as unsaturated FFAs with even and odd numbered C‐atom chains were present in both cuticular and internal lipids. The alcohol fractions of L. sericata were represented by free, straight‐chain primary alcohols containing an even number of C‐atoms. The lipid composition of male and female L. sericata adults and the hydrocarbon composition of all stages of L. sericata had previously been analyzed. To have a full overview of the lipid composition and to identify similarities or dissimilarities between the individual lipid fractions in this insect species, two‐way hierarchical cluster analysis (HCA) was performed using also the data from these previous publications. The content of FFA 18 : 1 (n‐9) was noticed to be very high in the cuticular fractions of larvae and pupae as well as in all internal fractions (male, female, larvae, and pupae) and low in the cuticular fractions of male and female imago. The contents of FFAs 16 : 0 and 16 : 1 (n‐9), cholesterol, and the n‐alkanes n‐C₃₁, n‐C₂₉, n‐C₂₇, n‐C₂₅, and n‐C₂₃ varied between particular fractions, whereas the amounts of other compounds were similar in all fractions.     

Bacteria abundance and diversity of different life stages of Plutella xylostella (Lepidoptera: Plutellidae), revealed by bacteria culture‐dependent and PCR‐DGGE methods

Microbial abundance and diversity of different life stages (fourth instar larvae, pupae and adults) of the diamondback moth, Plutella xylostella L., collected from field and reared in laboratory, were investigated using bacteria culture‐dependent method and PCR‐DGGE analysis based on the sequence of bacteria 16S rRNA V3 region gene. A large quantity of bacteria was found in all life stages of P. xylostella. Field population had higher quantity of bacteria than laboratory population, and larval gut had higher quantity than pupae and adults. Culturable bacteria differed in different life stages of P. xylostella. Twenty‐five different bacterial strains were identified in total, among them 20 strains were presented in larval gut, only 8 strains in pupae and 14 strains in adults were detected. Firmicutes bacteria, Bacillus sp., were the most dominant species in every life stage. 15 distinct bands were obtained from DGGE electrophoresis gel. The sequences blasted in GenBank database showed these bacteria belonged to six different genera. Phylogenetic analysis showed the sequences of the bacteria belonged to the Actinobacteri, Proteobacteria and Firmicutes. Serratia sp. in Proteobacteria was the most abundant species in larval gut. In pupae, unculturable bacteria were the most dominant species, and unculturable bacteria and Serratia sp. were the most dominant species in adults. Our study suggested that a combination of molecular and traditional culturing methods can be effectively used to analyze and to determine the diversity of gut microflora. These known bacteria may play important roles in development of P. xylostella.     

In vitro antibacterial activity and physicochemical properties of a crude methanol extract of the larvae of the blow fly Lucilia cuprina

The emergence of multidrug‐resistant bacterial strains has prompted the reintroduction of maggot therapy in the treatment of chronic, infected wounds. Many previous studies have demonstrated the potent antibacterial activity of larval excretions/secretions of the blowfly Lucilia sericata (Meigen) (Diptera:Calliphoridae) against bacteria. However, the antibacterial activity of its sibling species, Lucilia cuprina (Wiedemann) (Diptera:Calliphoridae) against a wide range of pathogenic bacteria has never been determined. The aim of this study was to develop a new procedure to produce whole body extract of larvae of L. cuprina via methanol extraction as well as to demonstrate the in vitro antibacterial activity of this extract against seven selected wound pathogens (Staphylococcus aureus, methicillin‐resistant S. aureus, S. epidermidis, Streptococcus pyogenes, Klebsiella pneumoniae, Pseudomonas aeruginosa and Escherichia coli). The turbidimetric assay demonstrated that L. cuprina larval extract was significantly potent against all bacteria tested (P < 0.001). Additionally, colony‐forming unit (CFU), agar well diffusion and minimum inhibitory concentration assays have confirmed the apparent potency of larval extract against P. aeruginosa. The reconstituted larval extract was highly robust and thermally stable. These observations substantiated the feasibility of the methanol extraction method in the production of larval extract.     

Microbial studies of compost: bacterial identification,and their potential for turfgrass pathogen suppression

Composting is the degradation of organic materials through the activities of diverse microorganisms. This research examined microbial community dynamics, population levels and identification of bacteria throughout the composting process and in storage. In addition, an evaluation was performed to determine the potential for dominant bacterial isolates to suppress selected turfgrass pathogens: Sclerotinia homoeocarpa, Pythium graminicola, Typhula ishikariensis, and Microdochium nivale, responsible for causing the turfgrass diseases dollar spot, pythium blight, typhula blight, and fusarium patch, respectively. Composts supported high population levels of bacteria with 78% of cultures tested being Gram-negative. Proteolytic activity, found in 29% of cultures tested is a potential mechanism of suppression or competition with other microorganisms. Although the Biolog system did not identify a wide range of bacteria, the main Gram-negative genera identified in mature compost were Pseudomonas (28%), Serratia (20%), Klebsiella (11%), and Enterobacter (5%). Twenty-one percent of isolates tested were not identified by Biolog, and many more had similarity indexes < 0.50. The microbial identification system, based on whole cell fatty acid analysis, identified a wide range of bacteria, with a higher proportion of similarities than the Biolog system. Genera common to both testing procedures included Pseudomonas, Serratia, and Enterobacter. All Gram-positives were identified as Bacillus spp. Phospholipid fatty acid analysis, used to estimate the diversity of microbial communities, was useful in monitoring changes in microbial population in storage and during composting, as well as estimating levels of compost maturity. Plate challenge experiments revealed a number of cultures with antagonistic activity against turfgrass pathogens. There were 52, 31, 32 and 19% of the bacterial isolates tested that exhibited antagonistic activity against S. homoeocarpa, P. graminicola, T. ishikariensis, and M. nivale, respectively. Improved understanding of microbial populations and their dynamics in composts will expand their potential to act as suppressants on pathogenic fungi or turfgrass.     

Shifting microbiomes complement life stage transitions and diet of the bird parasite Philornis downsi from the Galapagos Islands

Domestication disconnects an animal from its natural environment and diet, imposing changes in the attendant microbial community. We examine these changes in Philornis downsi (Muscidae), an invasive parasitic fly of land birds in the Galapagos Islands. Using a 16S rDNA profiling approach we studied the microbiome of larvae and adults of wild and laboratory-reared populations. These populations diverged in their microbiomes, significantly more so in larval than in adult flies. In field-collected second-instar larvae, Klebsiella (70.3%) was the most abundant taxon, while in the laboratory Ignatzschineria and Providencia made up 89.2% of the community. In adults, Gilliamella and Dysgonomonas were key members of the core microbiome of field-derived females and males but had no or very low representation in the laboratory. Adult flies harbour sex-specific microbial consortia in their gut, as male core microbiomes were significantly dominated by Klebsiella. Thus, P. downsi microbiomes are dynamic and shift correspondingly with life cycle and diet. Sex-specific foraging behaviour of adult flies and nest conditions, which are absent in the laboratory, may contribute to shaping distinct larval, and adult male and female microbiomes. We discuss these findings in the context of microbe–host co-evolution and the implications for control measures.     

ε-Caprolactam Utilization by Proteus sp. and Bordetella sp. Isolated From Solid Waste Dumpsites in Lagos State, Nigeria, First Report

The ε-caprolactam is the monomer of the synthetic non-degradable nylon-6 and often found as nonreactive component of nylon-6 manufacturing waste effluent. Environmental consequences of its toxicity to natural habitats and humans pose a global public concern. Soil samples were collected from three designated solid waste dumpsites, namely, Abule-Egba, Olusosun and Isheri-Igando in Lagos State, Nigeria. Sixteen bacteria isolated from these samples were found to utilize the ε-caprolactam as a sole source of carbon and nitrogen at concentration of ≤20 g l^?1. The isolates were characterized using their 16S rRNA gene sequence and showed similarity with Pseudomonas sp., Proteus sp., Providencia sp., Corynebacterium sp., Lysinibacillus sp., Leucobacter sp., Alcaligenes sp. and Bordetella sp. Their optimal growth conditions were found to be at temperature range of 30 to 35 °C and pH range of 7.0–7.5. High Performance liquid chromatography analysis of the ε-caprolactam from supernatant of growth medium revealed that these isolates have potential to remove 31.6–95.7 % of ε-caprolactam. To the best of our knowledge, this study is first to report the ability of Proteus sp. and Bordetella sp. for ε-caprolactam utilization.     

Prevalence of co-resistance to disinfectants and clinically relevant antibiotics in bacterial isolates from three hospital laboratory wastewaters in Southwestern Nigeria

The prevalence of co-resistance to four disinfectants and seven antibiotics was investigated among 57 bacterial strains isolated from the effluents of three hospital laboratories in Ogbomoso, Southwestern Nigeria. The organisms belonging to seven genera of public health importance such as Pseudomonas, Streptococcus, Serratia, Staphylococcus, Klebsiella, Proteus and Bacillus showed varying degrees of resistance to the test antimicrobial agents ranging from 0% to 77.8%. From among 25 organisms isolated from hospital A were recognized 16 phenotypic patterns of co-resistance to the test disinfectants and antibiotics; while from hospitals B and C were recognized 13 and 9 patterns, respectively, from among 18 and 14 isolates. The observed co-resistance to antimicrobial agents among the organisms reported in the present study is an indication of the risks posed by the untreated effluents to public health. It also adds to the increasing evidence about the role of hospital wastewaters as environmental reservoir of multi-drug-resistant bacteria.