Denaturing Gradient Gel Electrophoresis Research Articles

Chemical and Microbiological Assessment of Wastewater Discharged Along the Mediterranean Sea

The large discharges of wastewater in different natural receiving environments, particularly the marine environment, have massively contributed to pollution. This study examined the physicochemical and microbiological quality of wastewater discharged along the Mediterranean Sea. This investigation is one of the few works carried out by scientists along with the Mediterranean countries. Wastewater sampling was carried out in Egypt, Morocco, Algeria, Tunisia, and Italy. Analyses confirmed that the quality of treated wastewater was always better than the ones registered as raw wastewater. In addition, the quality of the treated wastewater and seawater appeared to be adequate and satisfied the standard and recommended limits in vigor in all these Mediterranean countries. These results showed that the wastewater treatment process used in Italy allowed a higher reduction in most tested parameters (COD: 80.44%, BOD5: 58.9%, OM: 70.74%, TOC: 78.4%). The bacteriological quality of these waters and their diversification was assessed by the denaturing gradient gel electrophoresis (DGGE) technique. Firmicutes, Gamma-Proteobacteria, and Beta-Proteobacteria in 42% of the DGGE DNA bands, and predominately some lineages affiliated to cultivable and non-cultivable clones of Bacteroides (58%), were found. The examination of antibiotic susceptibility at the level of 18 strains isolated from various arbitrary water samples showed that most of these isolates exhibited resistance to at least one antibiotic family, and 11 isolates exhibited 100% resistance against aztreonam. This result confirms the large antibiotic-resistance spreading and circulation registered these last decades in the natural environment, conditioned by the extensive and non-controlled use of antibiotics for human therapy and animal feeding.

Easy Removal of Epiphytic Bacteria on Ulva (Ulvophyceae, Chlorophyta) by Vortex with Silica Sands.

Macroalgae-associated bacteria play an important role in their algal hosts’ biological processes. They are localized on surfaces of the host thalli, as well as between and even within algal cells. To examine the differences in community structures and functions between epi- and endo- bacteria, an effective approach for maximizing epiphyte removal from delicate seaweeds while retaining endophyte fidelity must be developed. In this study, a variety of surface sterilization methods for Ulva prolifera were compared, including mechanical, chemical, and enzymatical treatments. According to the results of scanning electron microscope (SEM) and denaturing gradient gel electrophoresis (DGGE) analysis, almost complete removal of epiphytic bacteria on Ulva was obtained simply by co-vortex of seaweeds with silica sands, causing minimal disturbance to endosymbionts when compared to previous published methods. In addition, the adaptability was also confirmed in additional U. prolifera strains and Ulva species with blade-like or narrow tubular thallus shapes. This easy mechanical method would enable the analysis of community composition and host specificity for Ulva-associated epi- and endo-bacteria separately.

Effect of daily co-exposure to inulin and chlorpyrifos on selected microbiota endpoints in the SHIME® model

The intestinal microbiota has a key role in human health via the interaction with the somatic and immune cells in the digestive tract environment. Food, through matrix effect, nutrient and non-nutrient molecules, is a key regulator of microbiota diversity. As a food contaminant, the pesticide chlorpyrifos (CPF) has an effect on the composition of the intestinal microbiota and induces perturbation of microbiota. Prebiotics (and notably inulin) are known for their ability to promote an equilibrium of the microbiota that favours saccharolytic bacteria. The SHIME® dynamic in vitro model of the human intestine was exposed to CPF and inulin concomitantly for 30 days, in order to assess variations in both the bacterial populations and their metabolites. Various analyses of the microbiota (notably temporal temperature gradient gel electrophoresis) revealed a protective effect of the prebiotic through inhibition of the enterobacterial (E. coli) population. Bifidobacteria were only temporarily inhibited at D15 and recovered at D30. Although other potentially beneficial populations (lactobacilli) were not greatly modified, their activity and that of the saccharolytic bacteria in general were highlighted by an increase in levels of short-chain fatty acids and more specifically butyrate. Given the known role of host-microbiota communication, CPF's impact on the body's homeostasis remains to be determined.

Effect of In Situ Bioremediation of Soil Contaminated with DDT and DDE by Stenotrophomonas sp. Strain DXZ9 and Ryegrass on Soil Microorganism

In the present study, the changes in the microbial populations, enzyme activity and bacterial community structure in contaminated soils were investigated during the bioremediation of using Stenotrophomonas sp. strain DXZ9 and ryegrass. The results showed that the removal rates were 81% for DDT and 55% for DDE (69% for DDTs) with ryegrass-microbe. Microbial activity was remarkably improved, and the number of bacteria increased sharply from 7.32 × 106 to 2.56 × 108 cells/g in the 10 days due to successful colonization of the strains and effects of the ryegrass rhizosphere. There was significant difference in fungi number with ryegrass when comparing the 30th and 90th days with the 210th day: The actinomycete number in the soil with ryegrass was higher than without ryegrass, and it indicated that the number of microorganisms significantly increased under the action of ryegrass. The activities of polyphenol oxidase, dehydrogenase and catalase were significantly activated by the combination of ryegrass and microbe, and urease activity was less affected: It has influence on the diversity of bacterial community structure in the soil, but its influence gradually decreased by denaturing gradient gel electrophoresis with an extension in time. The activities represented promising tools for decontaminating and restoring the ecosystem in sustainable ways, and proposing new approaches and technological bottlenecks to promote DDT biodegradation is very significant.

PCR-DGGE Analysis Proves the Suppression of Rhizoctonia and Sclerotium Root Rot Due to Successive Inoculations

The soil-borne pathogens Rhizoctonia solani and Sclerotium rolfsii have emerged as major pathogens of radish (Raphanus sativus) worldwide. The induction of soil suppressive of radish root rot disease was evaluated in soil repeatedly inoculated with R. solani, nonpathogenic binucleate Rhizoctonia sp. AG-A W1 (BNR) and S. rolfsii. The repeated inoculations of soil with R. solani and BNR significantly suppressed the disease severity of R. solani and S. rolfsii compared to the control. In contrast, the repeated inoculation of soil with S. rolfsii significantly suppressed only the pathogen, S. rolfsii. The community structure was examined using PCR-DGGE (polymerase chain reaction denaturing gradient gel electrophoresis) method. The bands of Trichoderma sp. were observed in the first, second and third inoculations of the soil with BNR. Similarly, bands of Trichoderma sp. were observed in the second and third inoculations of the soil with S. rolfsii and R. solani. Compared to the control, disease severity was significantly reduced in the soil repeatedly inoculated with S. rolfsii and R. solani . In conclusion, Trichoderma species were accumulated in specific patterns depending on the applied fungal inoculum in the suppressive soil.

Airborne bacterial community associated with fine particulate matter (PM2.5) under different air quality indices in Temuco city, southern Chile.

Temuco (Chile) is one of the most polluted cities in Chile and Latin America. Although the fine fraction of particulate matter (PM2.5) has been extensively studied and monitored due to its negative impact on public health, its microbiological components remain unknown. We explored, the airborne bacterial community in PM2.5 under good, moderate, alert, pre-emergency and emergency indices of air quality (AQIs) established by the Chilean government. Bacterial community relationship with environmental factors (PM2.5, PM10, carbon monoxide, among others), was also evaluated. Significant differences in PM2.5 bacterial community composition associated with AQIs were revealed, using 16S rRNA target sequences of denaturing gradient gel electrophoresis (DGGE) bands. Bacterial communities in PM2.5 were mainly clustered (80%) into emergency and pre-emergency samples. The dominant phylum was Proteobacteria and most abundant genus was Novosphingobium, traditionally related to opportunistic respiratory diseases. The main factors associated with community structure were PM2.5, PM10 and carbon monoxide concentrations. This study exposed that bacterial community composition in Temuco varies according to AQIs, with the occurrence of potential opportunistic bacteria on heavily polluted days.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00203-021-02740-6.

Effects of ferulic and p-hydroxybenzoic acids on Fusarium community structure and abundance in cucumber seedling rhizosphere

Soil microorganisms play an important role in agricultural ecosystem. However, there is little information about the effects of putative allelochemicals on specific soil microorganisms in vivo. Cucumber seedlings were treated with four concentrations of ferulic and p-hydroxybenzoic acids (0–1.0 μmol·g−1 soil) in soil. Effects of ferulic and p-hydroxybenzoic acids on rhizosphere Fusarium community structures and abundance were analyzed by polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and real-time PCR techniques, respectively. The results showed that ferulic acid at concentrations of 0.25, 0.5, and 1.0 μmol·g−1 soil significantly reduced the number of bands of Fusarium, and ferulic acid at concentrations of 0.5 and 1.0 μmol·g−1 soil significantly reduced Shannon–Wiener and evenness index of Fusarium community. All concentrations of p-hydroxybenzoic acid changed the community structure of Fusarium, including decreasing the number of bands, Shannon–Wiener, and evenness index. Ferulic and p-hydroxybenzoic acids at all concentrations significantly promoted the abundance of Fusarium. Ferulic and p-hydroxybenzoic acids at 0.5 μmol·g−1 soil had the highest Fusarium abundance among all treatments. These results indicate that four concentrations of ferulic acid had various effects on Fusarium, which was different from p-hydroxybenzoic acid, and this may be related to the cucumber autotoxicity, giving us a further understanding of soil sickness.

Estudio mediante técnicas moleculares del tanatomicrobioma intestinal en la estimación del intervalo post mortem temprano empleando un modelo de ratón

IntroductionCurrently, the lack of reliable quantitative methods has led different research lines to find a model that predicts the postmortem interval (PMI). The thanatomicrobiome, present from the moment of death, has been shown to change in predictable ways, allowing a correlation with PMI. Materials and methodsIn this study, the shifts of the thanatomicrobiome in the region of the posterior small intestine and the ascending colon in Mus musculus during the first 24 hrs of decomposition have been analyzed experimentally. For this purpose, a molecular approach based on the analysis of the 16S ribosomal gene (16S rRNA) and a denaturing gradient gel electrophoresis (DGGE) was adopted, followed by analyses of the ecological diversity indices Alpha and beta diversity. ResultsThe results based on the analysis of the ecological diversity indices reflected statistically significant changes before 12 hrs, and a decrease in diversity after 12 hrs postmortem, this being statistically significant in the two intestinal regions analyzed. Moreover, the comparative study of microbial communities indicated distinct and structured changes from the moment of death, with shifts in the degree of similarity from the composition detected in life (PMI 0 hrs). DiscussionThese results agree with other studies demonstrating a decrease in microbial diversity. However, under the conditions of the study, this decrease does not begin until 12 hrs after death. ConclusionsIn conclusion, by examining the dynamics of bacterial diversity our study has identified phases during decomposition that could help to improve microbial correlation models for PMI estimation.

Succession and Catabolic Properties of Fungal Community During Composting of Fruit Waste at Sub-Tropical Environment

A comprehensive profile of structural and functional dynamics of the fungal community during fruit waste composting was investigated. For this purpose, fruit waste was composted in a windrow setup in a sub-tropical environment for 146 days. Representative samples were collected at varied range of temperatures during composting and employed to physicochemical and microbiological analysis. Time-series data revealed that variation in fungal load is temperature dependent that influenced morphotypes’ shifts during different stages of composting. Shifts in abiotic factors, availability of accessible nutrients, water loss, pH and electrical conductivity (EC) participated in the transition of community and compost maturity. Fungal community shifts were studied using a culture-based method, denaturing gradient gel electrophoresis (DGGE) and Illumina sequencing. The Ascomycota were the most common phylum recovered using culture-based and DGGE methods. However, Illumina sequencing revealed a predominance of phylum Zygomycota (Mortierella sp, Rhizomucor sp), which had a low representation in the culture-based study, and phylum Basidomycota (Coprinopsis sp, Coprinellus canistri & Coprinus cordisporus), which was absent in the culture-based study. In contrast, Aspergillus fumigatus (ADIF1), which was found to be the most promising cellulase and pectinase producer at higher temperatures in culture-based studies, had a very low representation in molecular studies. The current findings imply that compost is a habitat for a diverse fungal population, it should be investigated using molecular approaches to study in-depth fungal ecology. Furthermore, the transformation of fruit waste into seed germination-friendly compost via a diverse fungal community yields an efficient organic fertilizer.

Community-Based 16S rDNA Fingerprinting Analysis of Geographically Distinct Marine Sediments of Unexplored Coastal Regions of Palk Bay and Gulf of Mannar.

The present study aims to carefully delineate the bacterial community composition in marine sediments from different geographical coastal regions of Palk Bay and Gulf of Mannar that are known for human recreational activities. Bacterial richness in different marine sediments was assessed using 16S rRNA gene-based Denaturing Gradient Gel Electrophoresis (DGGE) which is a widely deployed fingerprinting technique. The DGGE profiles revealed that the bacterial community profiles of sediment from different coastal regions were complex and dynamic. The most dominant phylum present in the marine sediment samples were Proteobacteria followed by Cyanobacteria, Bacteriodetes, Firmicutes, Acidobacteria, and Actinobacteria. Cosmopolitan presence of Thioalkalivibrio sp. was observed in all the marine sediments. Sequencing of the abundant band reveals the presence of Vibrio spp. in all the marine sediments. Comparative illumina data analysis revealed the presence of 51 different Vibrio species in which Vibrio alginolyticus holds the highest abundance (67.2%) followed by V. harveyi (13.5%). This is the one of the very few reports that compared the complex microbial community composition of the marine sediments of different geographical regions of unexplored coastal region. Further in-depth analysis needs to be taken to understand the presence of complex microbial compositions and their functions through high-throughput whole metagenome sequencing and metaproteomic approaches.

Bacterial population monitoring during alcoholic fermentation of mezcal in Durango by DGGE

Mezcal is the second most important alcoholic beverage produced in Mexico, and the microorganisms present during the fermentation process are primarily responsible for its organoleptic characteristics. Among these, the bacterial populations have been less studied, mainly due to the difficulty of recovering them. The aim was to apply a culture-independent molecular technique to detect the bacterial populations involved in spontaneous mezcal fermentation in Durango State. Samples were obtained from several stages in the mezcal production line. Denaturing gradient gel electrophoresis (DGGE) analysis was performed using DNA extracted from isolated microorganisms and metagenomes obtained from samples directly taken from the fermentation process. This study indicated that non-isolated bacteria were significant in the fermentation process and indicated that the lactic acid and acetic acid bacterial populations present in the monitored process are similar to those present in other regions during fermentation, although they differ in some species that may play essential roles in the development of the typical organoleptic properties of mezcal produced in the State of Durango. Furthermore, this study indicates that culture-independent analysis by DGGE can reveal the bacterial diversity during the mezcal fermentation process without the use of complex isolation procedures and can be a useful tool for the analysis, monitoring and control of mezcal fermentation processes.

Converting tropical rainforest to native rubber plantations alters soil bacterial and fungal communities

Driven by soil biochemistry and plant community composition, soil microbial communities reflect land management and environmental conditions. To evaluate the effects of land-use change on soil microbial diversity, we used denaturing gradient gel electrophoresis (DGGE) combined with sequencing to compare bacterial and fungal community profiles between rubber plantation (RP) and nearby seasonal rainforests (SR). Rainforest soil generally had higher soil total C and microbial biomass C concentration, smaller soil aggregate proportions, and a soil pH below rubber plantation soil. The bacterial and fungal richness and diversity were similar after converting primary forests to rubber plantations. However, the composition of bacterial and fungal communities has significantly changed in rubber plantations. Basidiomycota, the predominant group of fungi, was significantly different between primary forests and rubber plantations. However, Basidiomycota showed higher heterogenetic distribution in the rainforest under rubber plantations. In conclusion, land-use changes mainly affect soil microbial community composition and heterogeneity distribution patterns, especially for saprotrophic fungi, which consist of changes in litter inputs and soil C conditions.

The Root Mycobiota of Betula aetnensis Raf., an Endemic Tree Species Colonizing the Lavas of Mt. Etna (Italy)

Betula aetnensis is an endemic tree of high conservation value, which thrives on the nutrient-poor volcanic soils of Mount Etna. Since plant–microbe interactions could play a crucial role in plant growth, resource uptake, and resistance to abiotic stresses, we aimed to characterize the root and rhizosphere microbial communities. Individuals from natural habitat (NAT) and forest nursery (NURS) were surveyed through microscopy observations and molecular tools: bacterial and fungal automated ribosomal intergenic spacer analysis (ARISA), fungal denaturing gradient gel electrophoresis (DGGE). B. aetnensis was found to be simultaneously colonized by arbuscular (AM), ectomycorrhizal (ECM), ericoid (ERM) fungi, and dark septate endophytes (DSE). A high diversity of the bacterial community was observed whilst the root fungal assemblage of NAT plants was richer than that of NURS. Root and rhizosphere fungal communities from NAT plants were characterized by Illumina MiSeq sequencing. Most of the identified sequences were affiliated to Helotiales, Pezizales, and Malasseziales. Ascomycota and Basidiomycota dominated roots and rhizosphere but differed in community structure and composition. ECM in the roots mainly belonged to Tylospora and Leccinum, while Rhizopogon was abundant in the rhizosphere. The Helotiales, including ERM (mostly Oidiodendron) and DSE (mostly Phialocephala), appeared the dominant component of the fungal community. B. aetnensis harbors an extraordinarily wide array of root-associated soil microorganisms, which are likely to be involved in the adaptation and resistance mechanisms to the extreme environmental conditions in volcano Etna. We argue that nursery-produced seedlings could lack the necessary microbiota for growth and development in natural conditions.

Effect of Jhum Cycles on <i>Acidobacteria</i> and <i>Burkholderia</i> Community in the Rhizosphere of Mixed Crops of Different Jhum Fields

In the present study, culture-dependent and independent [Denaturing gradient gel electrophoresis (DGGE)] approach were used to analyze the effect of fallow cycle on bacterial populations associated with mixed crops selected from three different jhum fallow cycles (5-, 10- and 20- years) of Changki village, Nagaland. Two important bacterial phyla viz. Acidobacteria and Burkholderia were selected for DGGE analysis. According to the DGGE banding profile, Acidobacteria showed more richness compared Burkholderia. The presence and absence of few of the bands in the profile indicate the community shifts in the selected jhum fields. Shannon diversity index was higher in Acidobacteria than Burkholderia. Multivariate analysis showed that Acidobacteria community structure was similar among the crop plants of the same fallow cycle. Burkholderia community did not show clear separation among fallow cycles although crop of same fallow cycle tend to group together. ANOSIM and PERMANOVA showed significant differences in rhizosphere community pattern among fallow cycles and the crop plants of same fallow cycles indicated that both fallow cycle and crop plants are factors determining the Acidobacteria and Burkholderia community composition in jhum soils which was also confirmed by the culture-dependent analysis. Culturable bacterial counts were dependent on media used and significantly different at different fallow cycles. Bacterial communities (both culturable and DGGE patterns) were correlated with soil nutrients suggesting their importance in stability of jhum soil. The present study revealed that both fallow cycle and host plant may be the key factors in shaping many bacterial communities in jhum soils.

The links among Enterocytozoon hepatopenaei infection, growth retardation and intestinal microbiota in different sized shrimp Penaeus vannamei

Increasing evidences have showed that a tight link among pathogen infection, physiological indicators and intestinal microbiota. To investigate effects of Enterocytozoon hepatopenaei (EHP) infection to growth retardation and intestinal microbiota, different sized Pacific white shrimp (Penaeus vannamei) infecting with EHP were studied. The shrimp with big, medium and small sized groups were from same batch of postlarvae and reared in one pond under the same diet and environmental conditions. Number of EHP copies revealed that the more EHP copies the smaller size of shrimp individuals. Denaturing gradient gel electrophoresis (DGGE) profiles showed intestinal bacterial patterns of small sized shrimp were similar to the middle sized shrimp, rather than the big sized shrimp. It implied that intestinal microbiota were influenced by severity of EHP infection and suggested the different sizes of shrimp were due to the successive infection period of EHP. Among the different sized groups, the relative abundance of Vibrio of small group was the highest, suggesting EHP infection could result in higher susceptibility to pathogen invasion. Our findings provided the evidence intestinal bacterial patterns altered by infection of EHP, the more EHP copies the smaller size of shrimp, and different sized individuals due to successive infection period of EHP.

Bacterioplankton Community as a Biological Element for Reservoirs Water Quality Assessment

The Water Framework Directive (WFD) is used to evaluate the water quality of aquatic ecosystems. Phytoplankton is the only biological element considered in the reservoirs water quality assessment. In this study, we aimed to assess the use of the bacterioplankton community as an indicator of water quality, using a culture-independent assay (denaturing gradient gel electrophoresis, DGGE). Four Portuguese reservoirs (Miranda, Pocinho, Aguieira and Alqueva) were analysed in four periods (autumn 2018, spring and autumn 2019, and spring 2020). Bacterial total abundance had similar values for Miranda, Pocinho and Aguieira, and generally lower values for Alqueva. Diversity and richness values did not show a clear trend. Negative correlations were observed between some nutrients and the bacterial community. Overall, members of Actinobacteria, Bacteroidetes, Cyanobacteria, Nitrospirae and Proteobacteria were identified in all sampling sites. In Alqueva, no spatial, temporal or water body quality relationships with bacterial community were observed, which may be due to its higher size, low water velocity rate and higher residence times. However, in Miranda, Pocinho and Aguieira, a strong spatial and temporal bacterial community dynamic was observed. Furthermore, the presence of some species (e.g., Acinetobacter sp.) may reflect the poor water quality that was not detected by the WFD approach.

Fucoidan Protects Against High-Fat Diet-Induced Obesity and Modulates Gut Microbiota in Institute of Cancer Research Mice.

Fucoidan possesses various biological activities, such as anticoagulant, immunomodulatory, anti-inflammatory, potential antioxidant, and others. In this study, we investigated the effect of fucoidan on high-fat diet-induced obesity, inflammation, and gut microbiota in Institute of Cancer Research mice. Mice were gavaged with 50 mg/(kg·d) (Fuc0.5 group) or 250 mg/(kg·d) (Fuc2.5 group) of fucoidan for 5 weeks. Fucoidan alleviated obesity and tissue damage by decreasing body weight and body mass index, decreasing body weight gain, improved organ index, liver steatosis, and improved the structure of the small intestine. In addition, fucoidan decreased total cholesterol, triglyceride, and low-density lipoprotein cholesterol, and increased high-density lipoprotein cholesterol. Moreover, fucoidan reduced serum lipopolysaccharide concentrations, tumor necrosis factor-α, and total bile acid. Furthermore, fucoidan improved the structure of gut microbiota and significantly increased the abundance (Shannon diversity index, evenness, and Faecalibacterium prausnitzii) determined by denaturing gradient gel electrophoresis and quantitative PCR. In conclusion, our study provides a scientific basis for fucoidan as a functional food for modulating the gut microbiota and protecting against obesity.

Genetic and functional diversity of soil bacteria and fungi from different microhabitats in a karst region in Southern China

Little is known about the difference between bacterial and fungal genetic and functional diversity in karst regions of south China. In this study, the genetic and functional diversity of bacteria and fungi in nine types of soil microenvironments in the karst region in Maolan National Nature Reserve in Guizhou were investigated by PCR-DGGE (Denaturing Gradient Gel Electrophoresis) and BIOLOG EcoPlates. Maolan National Nature Reserve is a UNESCO Biosphere Reserve and plays an important role in protecting the karst forest ecosystem and rare and endangered wild animals and plants in central Asia. The results showed that the diversity of both bacteria and fungi was high and the main factors influencing the diversity of bacteria and fungi were different. The bacterial community structure from different microhabitats under the same vegetation type had higher similarity than similar microhabitats in different vegetation types, which could indicate that the bacterial community structure was mainly controlled by vegetation. For fungi, similar microhabitat species under different vegetation types had higher similarities than different microhabitats species under the same vegetation type, which could indicate that the fungal community structure is mainly controlled by microhabitats. In addition, the metabolic patterns of similar microhabitats in different vegetation were different, while the metabolic patterns of different microhabitats in the same vegetation were not obviously different. In conclusion, the effect of vegetation types on soil microbial functional diversity was greater than that of microhabitats, and this difference was reflected by the different degrees of influence on soil microbial genetic diversity and community structure.

PCR-DGGE Analysis for Identification of Intestinal Bacteria in the Black Soldier Fly Larvae, Hermetia illucens, in Vietnam

Hermetia illucens, the so-called black soldier fly (BSF), has been reported as an important insect in treating domestic and agricultural manure wastes. With the ability to live well in the environment of decomposition or waste containing a variety of substances, many types of microorganisms can be related to the intestinal microflora, helping the larvae digest, grow and develop well, even creating protection against parasites and pathogens. The present study aimed to identify the microbial community associated with larvae and determine the dominant species in their intestine. To understand the role of intestinal microflora of BSF larvae for partly explaining the excellent treatment and the ability to live well in the waste environment, denaturing gradient gel electrophoresis (DGGE) and DNA sequencing methods were conducted in three parts of BSF larval intestine. The results indicated that the appearance of 11 dominant bands of larval intestinal microflora. Moreover, by using sequence alignment and phylogenetic analysis, our research has clearly classified seven specific strains of bacteria found in BSF larval intestine including Clostridium amazonese, Clostridium sporogenes, Clostridium tertium, Clostridium saccharolyticum, Actinomycetaceae, Dialister sp. and Dygonomonas. In particular, Clostridium is the most dominant genus compared to other groups and present in all three parts of larval intestine. The results obtained in this study provided insight into the bacterial community composition of black soldier fly larvae that can be used in the environmental, agricultural, and biomedical industries.

Additive inhibitory effects of heavy metals on phenol-utilizing microorganism

Effects of heavy metals on phenol-utilizing microorganisms that could co-metabolically degrade naphthol were investigated. Polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) identified these phenol-utilizing microorganisms as Alicycliphilus denitrificans K601, Alicycliphilus sp. R-2461, uncultured Alicycliphilus sp., and Acidovorax aerodenitrificans. Inhibitory effects of Pb, Cu, Cd, and Zn on phenol biodegradation were in the order of Cu > Cd > Pb > Zn. Inhibitory effects of mixed heavy metals on phenol-utilizing microorganisms were in the order of (Cd + Pb) ≈ (Cd + Cu) > (Zn + Pb) > (Zn + Cd) > (Pb + Cu) > (Zn + Cu). The presence of mixed heavy metals synergistically inhibited microbial degradation of phenol. The relationship between reaction constants and inhibition concentrations that caused 50% of the degradation rate (IC50) for mixed heavy metals was derived as k2 = 0.69 ∙ IC50-1.007. In this study, heavy metals inhibited phenol biodegradation through synergistic interactions. However, other studies have reported antagonistic interactions depending on the microbial community and heavy metals, indicating that the inhibition type of heavy metal on microbial degradation depends on the microorganism and the type of heavy metal.