scholarly journals Forensic DNA Profiling of Bacterial Communities in Soil

2021 ◽  
Author(s):  
◽  
Rachel Parkinson

<p>Soil is frequently encountered as trace evidence in forensic science case-work, but because of the limitations of current analytical techniques, this evidence is rarely utilised. A technique has been developed that allows comparisons of soil samples to be made, based on molecular analysis of the bacterial communities living in the soil. This project assesses the practicality of using this technique, known as 16S rDNA T-RFLP community profiling, for forensic soil analysis, by refining the basic methodology and performing a preliminary evaluation of its reproducibility and utility. Initial difficulties associated with generating profiles from soil samples have been overcome through methodology improvement, and the technique has been found to be effective for generating simple, visual profiles that clearly demonstrate differences between soil samples. Soil bacterial community DNA profiling is likely to be a powerful yet simple forensic tool, providing the ability to routinely use soil as associative evidence. The potential for using the same technology to develop a time since death or post mortem interval (PMI) estimation tool was also investigated. This study monitored the changes in the soil bacterial community beneath decomposing human cadavers and pig carcasses and showed that community change is dynamic and progressive. These changes are caused by fluctuations in specific bacterial species populations that are able to utilise organic breakdown products released from the body over time. Release of the body’s natural microflora into the underlying soil may also contribute to an altered bacterial community. This project has demonstrated that the soil microbial community clearly changes over the course of decomposition, and potential exists for development of a PMI estimation tool based on soil bacterial community succession.</p>

2021 ◽  
Author(s):  
◽  
Rachel Parkinson

<p>Soil is frequently encountered as trace evidence in forensic science case-work, but because of the limitations of current analytical techniques, this evidence is rarely utilised. A technique has been developed that allows comparisons of soil samples to be made, based on molecular analysis of the bacterial communities living in the soil. This project assesses the practicality of using this technique, known as 16S rDNA T-RFLP community profiling, for forensic soil analysis, by refining the basic methodology and performing a preliminary evaluation of its reproducibility and utility. Initial difficulties associated with generating profiles from soil samples have been overcome through methodology improvement, and the technique has been found to be effective for generating simple, visual profiles that clearly demonstrate differences between soil samples. Soil bacterial community DNA profiling is likely to be a powerful yet simple forensic tool, providing the ability to routinely use soil as associative evidence. The potential for using the same technology to develop a time since death or post mortem interval (PMI) estimation tool was also investigated. This study monitored the changes in the soil bacterial community beneath decomposing human cadavers and pig carcasses and showed that community change is dynamic and progressive. These changes are caused by fluctuations in specific bacterial species populations that are able to utilise organic breakdown products released from the body over time. Release of the body’s natural microflora into the underlying soil may also contribute to an altered bacterial community. This project has demonstrated that the soil microbial community clearly changes over the course of decomposition, and potential exists for development of a PMI estimation tool based on soil bacterial community succession.</p>


Forests ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 51 ◽  
Author(s):  
Jiangmei Qiu ◽  
Jianhua Cao ◽  
Gaoyong Lan ◽  
Yueming Liang ◽  
Hua Wang ◽  
...  

Land use patterns can change the structure of soil bacterial communities. However, there are few studies on the effects of land use patterns coupled with soil depth on soil bacterial communities in the karst graben basin of Yunnan province, China. Consequently, to reveal the structure of the soil bacterial community at different soil depths across land use changes in the graben basins of the Yunnan plateau, the relationship between soil bacterial communities and soil physicochemical properties was investigated for a given area containing woodland, shrubland, and grassland in Yunnan province by using next-generation sequencing technologies coupled with soil physicochemical analysis. Our results indicated that the total phosphorus (TP), available potassium (AK), exchangeable magnesium (E-Mg), and electrical conductivity (EC) in the grassland were significantly higher than those in the woodland and shrubland, yet the total nitrogen (TN) and soil organic carbon (SOC) in the woodland were higher than those in the shrubland and grassland. Proteobacteria, Verrucomicrobia, and Acidobacteria were the dominant bacteria, and their relative abundances were different in the three land use types. SOC, TN, and AK were the most important factors affecting soil bacterial communities. Land use exerts strong effects on the soil bacterial community structure in the soil’s surface layer, and the effects of land use attenuation decrease with soil depth. The nutrient content of the soil surface layer was higher than that of the deep layer, which was more suitable for the survival and reproduction of bacteria in the surface layer.


Author(s):  
Zufei Xiao ◽  
Beihong Zhang ◽  
Yangbao Wang ◽  
Zhinong Jin ◽  
Feng Li ◽  
...  

Abstract: Plant types and soil bacterial communities had a close relationship, understanding the profound association between them contributes to better learn bacterial ecological function for plant growth. In this study, rhizosphere soil of six different chemotype Cinnamomum camphora trees were collected, including C. bodinieri var. citralifera, [C. camphora (Linn.) Presl], camphora-type, cineole-type, linalool-type and isoborneol-type. Soil properties content and bacterial communities were analyzed. Two chemotype C. camphora, including [C. camphora (Linn.) Presl] and linalool-type, shaped similar bacterial community structure, decreased Firmcutes relative abundance. richness estimators (Chao1 index and Ace index) of [C. camphora (Linn.) Presl] were decreased compared with the others. Furthermore, soil bacterial community structure was also similar among bodinieri var. citralifera, camphora-type, cineole-type and isoborneol-type. Hence, different chemotype C. camphora altered soil nutrient and shaped rhizosphere bacterial communities.


PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12105
Author(s):  
Fangnan Xiao ◽  
Yuanyuan Li ◽  
Guifang Li ◽  
Yaling He ◽  
Xinhua Lv ◽  
...  

Tamarix is a dominant species in the Tarim River Basin, the longest inland river in China. Tamarix plays an important role in the ecological restoration of this region. In this study, to investigate the soil bacterial community diversity in Tamarix shrubs, we collected soil samples from the inside and edge of the canopy and the edge of nebkhas and non-nebkhas Tamarix shrubs located near the Yingsu section in the lower reaches of Tarim River. High throughput sequencing technology was employed to discern the composition and function of soil bacterial communities in nebkhas and non-nebkhas Tamarix shrubs. Besides, the physicochemical properties of soil and the spatial distribution characteristics of soil bacteria and their correlation were analyzed. The outcomes of this analysis demonstrated that different parts of Tamarix shrubs had significantly different effects on soil pH, total K (TK), available K (AK), ammonium N (NH4+), and available P (AP) values (P < 0.05), but not on soil moisture (SWC), total salt (TDS), electrical conductivity (EC), organic matter (OM), total N (TN), total P (TP), and nitrate N (NO3−) values. The soil bacterial communities identified in Tamarix shrubs were categorized into two kingdoms, 71 phyla, 161 classes, 345 orders, 473 families, and 702 genera. Halobacterota, unidentified bacteria, and Proteobacteria were found to be dominant phyla. The correlation between the soil physicochemical factors and soil bacterial community was analyzed, and as per the outcomes OM, AK, AP, EC, and NH4+ were found to primarily affect the structure of the soil bacterial community. SWC, TK and pH were positively correlated with each other, but negatively correlated with other soil factors. At the phyla level, a significantly positive correlation was observed between the Halobacterota and AP, OM as well as Bacteroidota and AK (P < 0.01), but a significantly negative correlation was observed between the Chloroflexi and AK, EC (P < 0.01). The PICRUSt software was employed to predict the functional genes. A total of 6,195 KEGG ortholog genes were obtained. The function of soil bacteria was annotated, and six metabolic pathways in level 1, 41 metabolic pathways in level 2, and 307 metabolic pathways in level 3 were enriched, among which the functional gene related to metabolism, genetic information processing, and environmental information processing was found to have the dominant advantage. The results showed that the nebkhas and canopy of Tamarix shrubs had a certain enrichment effect on soil nutrients content, and bacterial abundance and significant effects on the structure and function of the soil bacterial community.


2021 ◽  
Vol 12 (4) ◽  
pp. 862-877
Author(s):  
Lara Mitia Castronovo ◽  
Sara Del Duca ◽  
Sofia Chioccioli ◽  
Alberto Vassallo ◽  
Donatella Fibbi ◽  
...  

The Sasso Fratino Integral Nature Reserve (Italy) aims to protect nature and territory. Since no anthropic activities are allowed, it represents a good model to study the bacterial community of a wild environment. The aim of this work was to characterise the cultivable and the total bacterial community of soil samples from the reserve in terms of taxonomy, composition, and structure. Seven soil samples were collected at different altitudes, and the chemical composition, the total and the cultivable microbiota, and the antibiotic resistance profiles of isolates were investigated. Total bacterial communities, studied through Next Generation Sequences analysis, included 390 genera. Samples differed in terms of microbial composition basing on the different altitude/vegetation of collection points. Random Amplified Polymorphic DNA Analysis (RAPD) allowed to identify 82 haplotypes out of 158 bacterial isolates. The taxonomic identification through 16S rDNA sequencing revealed that the strains were affiliated to 21 genera. Antibiotic resistance profiles of bacteria were also investigated, highlighting a high resistance against streptomycin and kanamycin. This work represents the first description of the soil bacterial community from the Natural Reserve of Sasso Fratino, and it is the first study considering the soil microbiota of an Italian integral nature reserve.


Author(s):  
Yinhong Hu ◽  
Weiwei Yu ◽  
Bowen Cui ◽  
Yuanyuan Chen ◽  
Hua Zheng ◽  
...  

Human disturbance and vegetation are known to affect soil microorganisms. However, the interacting effects of pavement and plant species on soil bacterial communities have received far less attention. In this study, we collected soil samples from pine (Pinus tabuliformis Carr.), ash (Fraxinus chinensis), and maple (Acer truncatum Bunge) stands that grew in impervious, pervious, and no pavement blocks to investigate the way pavement, tree species, and their interaction influence soil bacterial communities by modifying soil physicochemical properties. Soil bacterial community composition and diversity were evaluated by bacterial 16S amplicon sequencing. The results demonstrated that soil bacterial community composition and diversity did differ significantly across pavements, but not with tree species. The difference in soil bacterial community composition across pavements was greater in pine stands than ash and maple stands. Soil bacterial diversity and richness indices decreased beneath impervious pavement in pine stands, and only bacterial richness indices decreased markedly in ash stands, but neither showed a significant difference across pavements in maple stands. In addition, bacterial diversity did not differ dramatically between pervious pavement and no pavement soil. Taken together, these results suggest that pavement overwhelmed the effects of tree species on soil bacterial communities, and had a greater effect on soil bacterial communities in pine stands, followed by ash and maple stands. This study highlights the importance of anthropogenic disturbance, such as pavement, which affects soil microbial communities.


2020 ◽  
Author(s):  
Pamela Bhattacharya ◽  
Samrat Mondol ◽  
Gautam Talukdar ◽  
Gopal Singh Rawat

AbstractSoil heterotrophic respiration-driven CO2 emissions, its impact on global warming and the mechanistic roles of soil bacterial communities in this process have been an area of active research. However, our knowledge regarding the effects of environmental changes on soil bacterial communities is limited. To this end, the climate-sensitive high-altitude alpine ecosystems offer ideal opportunities to investigate relationship between climate change and bacterial communities. While data from several high-altitude mountain regions suggest that local environment factors and geological patterns govern bacterial communities, no information is available from the Himalaya. Here we provide baseline information on seasonal soil bacterial community diversity and composition along a 3200-4000 m elevation gradient covering four alpine habitats (subalpine forest, alpine scrub, alpine meadow and moraine) in Gangotri National Park, western Himalaya. Bacterial metabarcoding data from 36 field-collected samples showed no elevation trend in the bacterial richness and a non-monotonous decrease in their diversity. Further, their community diversity and composition varied significantly among habitats along elevation but were stable seasonally within each habitat. The richness was primarily influenced by soil inorganic carbon (SOC) and total nitrogen (TN), whereas temperature, SOC and TN affected diversity and composition patterns. Given the importance of the Himalaya in the context of global carbon cycle this information will help in accurate modeling of climate adaptation scenarios of bacterial niches and their downstream impacts towards climate warming.


Biology ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1329
Author(s):  
Zhi Yu ◽  
Kunnan Liang ◽  
Guihua Huang ◽  
Xianbang Wang ◽  
Mingping Lin ◽  
...  

Soil bacterial communities play crucial roles in ecosystem functions and biogeochemical cycles of fundamental elements and are sensitive to environmental changes. However, the response of soil bacterial communities to chronosequence in tropical ecosystems is still poorly understood. This study characterized the structures and co-occurrence patterns of soil bacterial communities in rhizosphere and bulk soils along a chronosequence of teak plantations and adjacent native grassland as control. Stand ages significantly shifted the structure of soil bacterial communities but had no significant impact on bacterial community diversity. Bacterial community diversity in bulk soils was significantly higher than that in rhizosphere soils. The number of nodes and edges in the bacterial co-occurrence network first increased and then decreased with the chronosequence. The number of strongly positive correlations per network was much higher than negative correlations. Available potassium, total potassium, and available phosphorus were significant factors influencing the structure of the bacterial community in bulk soils. In contrast, urease, total potassium, pH, and total phosphorus were significant factors affecting the structure of the bacterial community in the rhizosphere soils. These results indicate that available nutrients in the soil are the main drivers regulating soil bacterial community variation along a teak plantation chronosequence.


PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7304
Author(s):  
Xingjia Xiang ◽  
Sean M. Gibbons ◽  
He Li ◽  
Haihua Shen ◽  
Haiyan Chu

Background Changes in aboveground community composition and diversity following shrub encroachment have been studied extensively. Recently, shrub encroachment was associated with differences in belowground bacterial communities relative to non-encroached grassland sites hundreds of meters away. This spatial distance between grassland and shrub sites left open the question of how soil bacterial communities associated with different vegetation types might differ within the same plot location. Methods We examined soil bacterial communities between shrub-encroached and adjacent (one m apart) grassland soils in Chinese Inner Mongolian, using high-throughput sequencing method (Illumina, San Diego, CA, USA). Results Shrub-encroached sites were associated with dramatic restructuring of soil bacterial community composition and predicted metabolic function, with significant increase in bacterial alpha-diversity. Moreover, bacterial phylogenic structures showed clustering in both shrub-encroached and grassland soils, suggesting that each vegetation type was associated with a unique and defined bacterial community by niche filtering. Finally, soil organic carbon (SOC) was the primary driver varied with shifts in soil bacterial community composition. The encroachment was associated with elevated SOC, suggesting that shrub-mediated shifts in SOC might be responsible for changes in belowground bacterial community. Discussion This study demonstrated that shrub-encroached soils were associated with dramatic restructuring of bacterial communities, suggesting that belowground bacterial communities appear to be sensitive indicators of vegetation type. Our study indicates that the increased shrub-encroached intensity in Inner Mongolia will likely trigger large-scale disruptions in both aboveground plant and belowground bacterial communities across the region.


2016 ◽  
Vol 62 (9) ◽  
pp. 726-734 ◽  
Author(s):  
Rui Huang ◽  
Dayong Zhao ◽  
Jin Zeng ◽  
Feng Shen ◽  
Xinyi Cao ◽  
...  

To investigate soil bacterial richness and diversity and to determine the correlations between bacterial communities and soil properties, 8 soil samples were collected from the Huashan watershed in Anhui, China. Subsequently, 454 high-throughput pyrosequencing and bioinformatics analyses were performed to examine the soil bacterial community compositions. The operational taxonomic unit richness of the bacterial community ranged from 3664 to 5899, and the diversity indices, including Chao1, Shannon–Wiener, and Faith’s phylogenetic diversity ranged from 7751 to 15 204, 7.386 to 8.327, and 415.77 to 679.11, respectively. The 2 most dominant phyla in the soil samples were Actinobacteria and Proteobacteria. The richness and diversity of the bacterial community were positively correlated with soil pH. The Mantel test revealed that the soil pH was the dominant factor influencing the bacterial community. The positive modular structure of co-occurrence patterns at the genus level was discovered by network analysis. The results obtained in this study provide useful information that enhances our understanding of the effects of soil properties on the bacterial communities.


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