Fermentative Microorganisms Research Articles

Relationship between hindgut microbes and feed conversion ratio in Hu sheep and microbial longitudinal development.

Feed efficiency is an important indicator in the sheep production process, which plays an important role in improving economic benefits and strengthening energy conservation and emission reduction. Compared with the rumen, the fermentation of the hindgut microorganisms can also provide part of the energy for the host, and the composition of the hindgut microorganisms will affect the feed efficiency. Therefore, we hope to find new ways to regulate sheep feed efficiency by studying the sheep gut microbes. In this study, male Hu sheep with the same birth date were raised under the same conditions until 180 d old. The sheep were divided into high and low groups according to the feed conversion ratio (FCR) at 80 to 180 d old, and the differences in rectal microorganisms between the two groups were compared. The permutational multivariate analysis (PERMANOVA) test showed that there were differences in microorganisms between the two groups (P < 0.05). Combined with linear fitting analysis, a total of six biomarkers were identified, including Ruminobacter, Eubacterium_xylanophilum_group, Romboutsia, etc. Functional enrichment analysis showed that microorganisms may affect FCR through volatile fatty acids synthesis and inflammatory response. At the same time, we conducted a longitudinal analysis of the hindgut microbes, sampling nine-time points throughout the sheep birth to market stages. The microbiota is clearly divided into two parts: before weaning and after weaning, and after weaning microbes are less affected by before weaning microbial composition.

Opportunities to Production of Biofuel from Grains and to Improve the Factors Increasing the Yield of Bioethanol in a Short Time

When biofuels are used as an energy source, they are accepted as a renewable energy source that is safe for the environment and can replace fossil fuels at the same time. Additionally, using of organic materials obtained from plants and animals as biofuel is more advantageous compared to the formation of fossil fuels over hundreds of years. Therefore, biomass containing within itself substances such as sugar, starch, oil and cellulose, which have high energy availability, are considered as raw materials. While biodiesel is obtained from organic materials containing oil, ethanol and similar biofuels are generally obtained from organic materials containing sugar and starch. All these production stages vary depending on factors such as each plant species and variety, the amount of sugar contained in plants or sugar structures, the fermentation microorganisms used or the pretreatments applied. In this study, information is given about the stages of bioethanol production from grains and the issues affecting bioethanol yield.

Use of Characterized Microorganisms in Fermentation of Non-Dairy-Based Substrates to Produce Probiotic Food for Gut-Health and Nutrition

Most fermented foods are dairy-based products; however, foods prepared using non-dairy-based materials such as grains, cereals, vegetables, and fruits can meet the dietary requirements of consumers following different food practices, including vegans and consumers that have dietary issues with dairy-based products. Traditional food fermentations have been conducted by the functioning of bacterial and yeast cultures using the inoculum of uncharacterized microorganisms isolated from naturally fermenting foods. However, pure viable strains of microorganisms characterized as probiotic cultures have the potential for their application in the fermentation process. Such fermented foods can be labeled as probiotic products, displaying the names of strains and their viable number contained in the portion size of that specific product. The significance of the development of probiotic functional food is that they can be used as a source of nutrition; in addition, their consumption helps in the recovery of healthy gut microbiota. In a fermented food, two components—the fermented substrate and the microorganism(s)—are in a synergistic relationship and contribute to healthy gut microbiota. The intake of probiotic foods for sustainability of a healthy gut can manipulate the functioning of gut–brain axis. The aim of this article is to present a review of published research conducted with specific strains characterized as probiotics, which have been studied to perform the fermentation growing on the matrices of non-dairy-based substrates.

Effect of co-inoculation of different halophilic bacteria and yeast on the flavor of fermented soy sauce

The flavor of soy sauce is closely related to the succession and interaction of the microbial community during fermentation. In this study, the selected potential flavor-producing microorganisms (7 species of bacteria and 4 species of yeast) were applied in the co-culture rapid fermentation model and their growth, physicochemical changes, volatile flavor compounds (VFCs), and sensory characteristics were investigated. Results showed that yeast promoted the growth of bacteria, while bacteria inhibited the growth of yeast in the co-culture model. Based on the results of VFCs and sensory evaluation, the combined fermentation of Zygosaccharomyces rouxii and Lactobacillus fermentum was the best strategy out of the 40 combinations. The effect of this combination was also validated in a 20 L fermentation application of soy sauce, which indeed enhanced the intensity of sauce-like, fruity, smoky, and caramel-like notes, as well as umami and kokumi tastes. These results provide a theoretical basis for the exploration and industrial application of flavor-producing microorganisms in soy sauce fermentation.

Proteolysis Degree of Protein Corona Affect Ultrasound-Induced Sublethal Effects on Saccharomyces cerevisiae: Transcriptomics Analysis and Adaptive Regulation of Membrane Homeostasis.

Protein corona (PC) adsorbed on the surface of nanoparticles brings new research perspectives on the interaction between nanoparticles and fermentative microorganisms. Herein, the proteolysis of wheat PC adsorbed on a nano-Se surface using cell-free protease extract from S. cerevisiae was conducted. The proteolysis caused monotonic changes of ζ-potentials and surface hydrophobicity of PC. Notably, the innermost PC layer was difficult to be proteolyzed. Furthermore, when S. cerevisiae was stimulated by ultrasound + 0.1 mg/mL nano-Se@PC, the proportion of lethal and sublethal injured cells increased as a function of the proteolysis time of PC. The transcriptomics analysis revealed that 34 differentially expressed genes which varied monotonically were related to the plasma membrane, fatty acid metabolism, glycerolipid metabolism, etc. Significant declines in the membrane potential and proton motive force disruption of membrane were found with the prolonged proteolysis time; meanwhile, higher membrane permeability, membrane oxidative stress levels, membrane lipid fluidity, and micro-viscosity were triggered.

Quality relationship between smoked and air-dried bacon of Sichuan-Chongqing in China: Free amino acids, volatile compounds, and microbial diversity

The quality formation of Chinese bacon is closely related to flavor compounds and microbial composition; however, the contribution of microbial to flavor has not been fully explored. Previous studies have focused on the differences in microorganisms and flavor substances in smoked bacon. Thus, this study aims to investigate the relationship among microorganisms, free amino acids (FAAs), and volatile compounds (VOCs) in bacon produced by different drying processes. We analyzed the microbial composition by sequencing the V3–V4 region of the 16S rDNA gene and the fungal ITS2 region and flavor substances using an amino acid analyzer and chromatography-mass spectrometry (GC–MS). Results of taste activity values (TVA) and partial least squares discriminant analysis (PLS-DA) revealed that the flavor components of the two types of bacon had general and specific characteristics, with the key FAAs (glutamic acid, lysine, and alanine) being comparable and the key VOCs being dissimilar. Based on non-metric multidimensional scaling (NMDS) and linear discriminant analysis effect size (LefSe), bacteria had more biomarkers than fungi. Correlation analysis demonstrated that microorganisms, particularly bacteria (Staphylococcus and Salinivibrio), are crucial in regulating and shaping the flavor of bacon. Some sub-abundance of bacteria such as Kocuria enrich the flavor of bacon. These findings indicate that the simultaneous fermentation of multiple microorganisms is conducive to the recreation of the artisan flavor of Chinese bacon.

Sustainable Valorization of Tomato Pomace (Lycopersicon esculentum) in Animal Nutrition: A Review.

Under the background of the current shortage of feed resources, especially the shortage of protein feed, attempts to develop and utilize new feed resources are constantly being made. If the tomato pomace (TP) produced by industrial processing is used improperly, it will not only pollute the environment, but also cause feed resources to be wasted. This review summarizes the nutritional content of TP and its use and impact in animals as an animal feed supplement. Tomato pomace is a by-product of tomato processing, divided into peel, pulp, and tomato seeds, which are rich in proteins, fats, minerals, fatty acids, and amino acids, as well as antioxidant bioactive compounds, such as lycopene, beta-carotenoids, tocopherols, polyphenols, and terpenes. There are mainly two forms of feed: drying and silage. Tomato pomace can improve animal feed intake and growth performance, increase polyunsaturated fatty acids (PUFA) and PUFA n-3 content in meat, improve meat color, nutritional value, and juiciness, enhance immunity and antioxidant capacity of animals, and improve sperm quality. Lowering the rumen pH and reducing CH4 production in ruminants promotes the fermentation of rumen microorganisms and improves economic efficiency. Using tomato pomace instead of soybean meal as a protein supplement is a research hotspot in the animal husbandry industry, and further research should focus on the processing technology of TP and its large-scale application in feed.

The effect of slime accumulated in a long-term operating UASB using crude glycerol to treat S-rich wastewater

An up-flow anaerobic sludge blanket (UASB) reactor targeting sulfate reduction was operated under a constant TOC/S-SO42− ratio of 1.5 ± 0.3 g C/g S for 639 days using crude glycerol as carbon source. A filamentous and fluffy flocculant material, namely slime-like substances (SLS), was gradually accumulated in the bioreactor after the cease of methanogenic activity. The accumulation of SLS was followed by a decrease in the removal efficiencies and a deterioration in the performance. Selected characteristics of SLS were investigated to explore the causes of its formation and the effect of SLS on the UASB performance. Results showed that glycerol fermentation and sulfate reduction processes taking place in the reactor were mainly accomplished in the bottom part of the UASB reactor, as the sludge concentration in the bottom was higher. The accumulation of SLS in the UASB reactor caused sludge flotation that further led to biomass washout, which decreased the sulfate and glycerol removal efficiencies. Batch activity tests performed with granular sludge (GS), slime-covered granular sludge (SCGS) and SLS showed that there was no difference between GS and SLS in the mechanism of glycerol fermentation and sulfate reduction. However, the specific sulfate reduction rate of GS was higher than that of SLS, while SLS showed a higher glycerol fermentation rate than that of GS. The different rates in GS and SLS were attributed to the higher relative abundances of fermentative microorganisms found in SLS and higher relative abundances of sulfate reducing bacteria (SRB) found in GS.

Identification and validation of core microbes associated with key aroma formation in fermented pepper paste (Capsicum annuum L.)

Fermented peppers are usually obtained by the spontaneous fermentation of microorganisms attached to fresh peppers, and the variable microbial composition would lead to inconsistencies in flavor between batches. To demonstrate the roles of microorganisms in flavor formation, the core microbes closely associated with the key aroma compounds of fermented pepper paste were screened and validated in this study. Lactobacillus was the dominant bacterial genus in fermented pepper paste, whereas the main fungal genera were Alternaria and Kazachstania. Nine strains of the genera Lactobacillus, Weissella, Bacillus, Zygosaccharomyces, Kazachstania, Debaryomyces, and Pichia were isolated from fermented pepper paste. Eleven key aroma compounds were identified using gas chromatography combined with olfactometry and relative odor activity values. Correlation analysis showed that Zygosaccharomyces and Kazachstania were positively correlated with the majority of the key aroma compounds, whereas Lactobacillus was negatively correlated with them. Thus, Zygosaccharomyces and Kazachstania were identified as core genera associated with the key odorants. Finally, Zygosaccharomyces bisporus, Kazachstania humilis, and Lactiplantibacillus plantarum were used as starter cultures for fermented peppers, confirming that Z. bisporus and K. humilis were more beneficial for the key aroma compounds (e.g., acetate, linalool, and phenyl ethanol) rather than L. plantarum. This study contributed to understanding the flavor formation mechanism and provided references for the quality control of food fermentation.

Improving suppressive activity of compost on phytopathogenic microbes by inoculation of antagonistic microorganisms for secondary fermentation

Antimicrobial activity contributes to plant disease control property of composts but its source is still not clear. From composting cow manure during secondary fermentation, 50 microbial strains with antifungal activity were isolated and identified. Two bacterial strains Bacillus mojavensis B282 and Pseudomonas aeruginosa F288, antagonistic against both phytopathogenic fungi and bacteria, were respectively used as the inoculum of compost for secondary fermentation. Inoculation of B282 or F288 significantly shifted microbial community structure of compost and genera functionally linked to antagonistic activity and plant growth promotion were enriched. Notably, culturable cells of B282 increased by about 40 times during secondary fermentation. The inoculation of each strain significantly increased antifungal activity of compost extracts and enhanced disease suppressive effects of compost on wheat root rot. This study demonstrates that inoculation of compost-indigenous microorganisms could improve antimicrobial activity of compost and provides a low-cost strategy for producing bio-organic fertilizers with biocontrol function.

Processing of Biomass Prior to Hydrogen Fermentation and Post-Fermentative Broth Management.

Using bioconversion and simultaneous value-added product generation requires purification of the gaseous and the liquid streams before, during, and after the bioconversion process. The effect of diversified process parameters on the efficiency of biohydrogen generation via biological processes is a broad object of research. Biomass-based raw materials are often applied in investigations regarding biohydrogen generation using dark fermentation and photo fermentation microorganisms. The literature lacks information regarding model mixtures of lignocellulose and starch-based biomass, while the research is carried out based on a single type of raw material. The utilization of lignocellulosic and starch biomasses as the substrates for bioconversion processes requires the decomposition of lignocellulosic polymers into hexoses and pentoses. Among the components of lignocelluloses, mainly lignin is responsible for biomass recalcitrance. The natural carbohydrate-lignin shields must be disrupted to enable lignin removal before biomass hydrolysis and fermentation. The matrix of chemical compounds resulting from this kind of pretreatment may significantly affect the efficiency of biotransformation processes. Therefore, the actual state of knowledge on the factors affecting the culture of dark fermentation and photo fermentation microorganisms and their adaptation to fermentation of hydrolysates obtained from biomass requires to be monitored and a state of the art regarding this topic shall become a contribution to the field of bioconversion processes and the management of liquid streams after fermentation. The future research direction should be recognized as striving to simplification of the procedure, applying the assumptions of the circular economy and the responsible generation of liquid and gas streams that can be used and purified without large energy expenditure. The optimization of pre-treatment steps is crucial for the latter stages of the procedure.

Solar energy application and its effect on microorganisms in food waste anaerobic fermentation regulated by organic load

Semi-continuous anaerobic digestion (AD) of food waste (FW) was conducted by solar intelligent control system to explore the impact of temperature fluctuation on microorganisms and its engineering applicability. According to analysis of the AD system at different organic loading rate (OLR), introduction of the solar intelligent control system into AD could save electric energy. Temperature fluctuation caused by climate and other factors reduced methane production by 31.79%. Before reaching the optimum OLR, the methane yield increased with the promotion of OLR and was at the optimum when OLR = 4.5 kg ⋅ m−3 ⋅ d−1. Enzyme activities changed with the change of pH. Lower pH limited the enzyme activities. At the initial stage of the reaction, Clostridium and Lactobacillus dominated, which made content of amylase and lipase reach 264.07 U/mL (solar group), 331.02 U/mL (electric group), and 276.44 U/mL (solar group), 306.75 U/mL (electric group), respectively. Temperature fluctuation brought in by the solar intelligent control system had a great effect on microbial activity. Microbial community structure was influenced by the OLR change. Methanobacterium became the main methanogenic bacterium at the middle and late stage. After analysis, it is feasible to introduce solar energy into AD.

Биоконверсия целлюлозосодержащего сырья. Ферментативный гидролиз целлюлозы (обзор литературы)

Lignocellulose is the most abundant biopolymer on earth. The hydrolysis of lignocellulose to fermentable sugars is a prerequisite for its successful use as a substrate for the large-scale production of value-added industrial products. Enzymatic hydrolysis of lignocellulose is carried out by cellulases, hemicellulases, and ligninases in synergy or individually. The review describes the enzymatic hydrolysis of cellulose, hemicellulose, and lignin. Information on solid-phase and submerged microorganisms fermentation used to obtain cellulases was given. Methods for increasing the level of production and activity of cellulases were characterized. The industrial application of cellulases, including for the production of bioethanol, was described.

Methods of the Dehydration Process and Its Effect on the Physicochemical Properties of Stingless Bee Honey: A Review.

Stingless bee honey (SLBH) has a high moisture content, making it more prone to fermentation and leading to honey spoilage. Dehydration of SLBH after harvest is needed to reduce the moisture content. This review compiles the available data on the dehydration methods for SLBH and their effect on its physicochemical properties. This review discovered the dehydration process of vacuum drying at 60 °C and 5% moisture setting, freeze-drying at -54 °C and 5% moisture setting for 24 h, and using a food dehydrator at 55 °C for 18 h could extract &gt;80% water content in SLBH. As a result, these methods could decrease moisture content to &lt;17% and water activity to &lt;0.6. These will prevent the fermentation process and microorganism growth. The hydroxymethylfurfural (HMF) contents remain within the permissible standard of &lt;40 mg/kg. The total phenolic content increased after dehydration by these methods. Therefore, dehydration of SLBH is recommended to increase its benefits.

Dynamics of Microbial Communities, Flavor, and Physicochemical Properties during Ziziphus jujube Vinegar Fermentation: Correlation between Microorganisms and Metabolites.

Jujube pulp separated from Ziziphus jujube is often discarded after processing, resulting in a serious waste of resources and environmental pollution. Herein, Ziziphus jujube pulp was used as a raw material for vinegar fermentation. To investigate the dynamic distribution of microorganisms and flavor substances in ZJV, correlations between environmental variables (e.g., total acid, reducing sugar, temperature) and flavor substances (organic acids, amino acids, volatile substances) and microorganisms were analyzed. Physicochemical indicators (temperature, total acid, alcohol) were the main factors affecting ZJV fermentation. The middle and later stages of ZJV fermentation were the periods showing the largest accumulation of flavor substances. Organic acids (acetic acid, malic acid, citric acid, lactic acid), amino acids (Asp, Glu, Arg) and volatile substances (ethyl phenylacetate, phenethyl alcohol) were important odor-presenting substances in ZJV. In the bacterial community, the Operational Taxonomic Units (OTUs) with an average relative abundance of more than 10% in at least one fermentation stage were mainly Acetobacter, Lactobacillus and Saccharopolyspora, while it was Thermomyces in the fungal community. Pearson correlation coefficients showed that Penicillium, Lactobacillus and Acetobacter were the core microorganisms, implying that these microorganisms contributed to the flavor formation greatly in ZJV fermentation. This study reveals the correlation between physicochemical indexes and flavor substances and microorganisms in ZJV fermentation. The results of the study can provide a theoretical basis for the development of the ZJV industry.

Effect of Lactic Acid Bacteria on Bacterial Community Structure and Characteristics of Sugarcane Juice.

Fermentation technology is of great significance for food preservation; through fermentation, while extending the shelf life of food, it can also improve the sensory quality of food and increase its nutritional value. Compared with natural fermentation, the use of specific microorganisms for fermentation can be used to determine the direction of fermentation. Therefore, in order to better explore the effect of bacterial community structure on the quality of sugarcane juice naturally fermented and inoculated with different lactic acid bacteria in the fermentation process, the most suitable method for sugarcane juice fermentation was found, which provided a theoretical basis for the safe production of fermented sugarcane juice. In this experiment, the sugarcane juice was treated differently and divided into four groups: natural fermentation, fermentation with Lactobacillus HNK10, fermentation with Lactococcus HNK21, and HNK10 + HNK21 compound fermentation. The changes in bacterial community structure of different treatments of sugarcane juice during fermentation were analyzed by high-throughput sequencing technology, and the quality change of different treatments of sugarcane juice during fermentation was analyzed by high-performance liquid chromatography, and the change in its bacteriostatic ability was explored. The results showed that after the sugarcane juice treated with Lactobacillus HNK10 was fermented at 37 °C for 48 h, the final fermented sugarcane juice had a large abundance of lactic acid bacteria and high-quality and strong antibacterial activity. Conclusions: changes in the bacterial community structure during the fermentation of sugarcane juice affect the formation of organic acids and the change of bacteriostatic ability and directly determine the quality and shelf life of fermented sugarcane juice.

Grazing cotton crop residue to reduce winter supplementation cost in late-gestation beef cows and assessment of the negative effects of gossypol on fermentation of mixed ruminal microorganisms

This research aimed to evaluate the use of standing cotton crop residue as a winter supplementation source for gestating beef cows and the effects of gossypol, a naturally occurring pigment with potential anti-quality characteristics, on in vitro mixed ruminal microorganism fermentations. Experiment 1 used a 3-yr completely randomized study with 108 Angus cross cows (BW 559 ± 7.9 kg) enrolled in a 30-d grazing trial. Cows were weighed, stratified by weight, and randomly assigned to 1 of 2 treatments: dormant bermudagrass ( Cynodon dactylon ) pasture + bermudagrass hay (GR) or cotton ( Gossypium ) crop residue + bermudagrass hay (CT). Experiment 2 used a completely randomized in vitro mixed ruminal microorganism fermentation with 3 × 5 factorial arrangements of treatments. This included 3 substrates: corn ( Zea mays ; CC), average relative forage quality (RFQ 100) coastal bermudagrass (ABG), and high relative forage quality (RFQ 120) coastal bermudagrass (HBG), along with 5 concentrations of gossypol: 0, 0.0615, 0.123, 0.1845, or 0.246 mg of gossypol/mL. Total hay offered and hay per head per day were greater ( P ≤ 0.02) in the GR group compared with the CT group. Economic analysis indicated that total hay cost, cost per head per day, and cost of gain were all significantly decreased for cows in the CT treatment compared with cows in the GR treatment ( P < 0.002). In vitro DM digestibility and total VFA production were lower ( P < 0.002) as gossypol concentration reached the highest concentration. Results suggest that grazing cotton crop residue is a partial replacement for hay supplementation during the winter months. Increased levels of gossypol have negative effects on DM disappearance and VFA production. The gossypol amount found in crop residue is approximately the same as the lowest concentration evaluated in the in vitro experiment. These results indicate that grazing cotton crop residue should not influence ruminal fermentation.

Influence of nanomaterials in biohydrogen production through photo fermentation and photolysis - Review on applications and mechanism

The pressure on reducing greenhouse gas emissions has increased since the focus on climate change mitigation has grown. As the human development index is directly related to per capita energy consumption, sustainable energy production with reduced carbon footprint is the essential pathway for cleaner environment. Over numerous existing biological processes, hydrogen production via photo fermentation and photolysis of water is considered a more sustainable and economical method of hydrogen production. While both biological modes suffer from certain limitations, such as low yields and low production rates, practical implementation is still a long way off due to these limitations. The unique properties of nanomaterials (NMs) can help increase the efficiency of the biomass to biohydrogen process in significant ways. Applications of organic and inorganic nanoparticles in photocatalytic and photo fermentative hydrogen production is discussed in this paper. This review reports a wide range of applications of nanomaterials including the details of photo fermentative microorganisms and their mechanism of action. The maximum photo fermentative bio-H2 production was reported in the presence of SiC–Fe3O4(3.02 mol H2/mol acetate), Ni (41 mol H2/mol sugar), graphite-C3N4 (64.2 mol H2/mol sugar) whereas photocatalytic bio-H2 yield was highest when Pd–Ni/CdS (54 mmol/g.h), Ni-MO/g-C3N4 (1785 mmol/g.h) and CuO/TiO2 (20.3 mmol/g.h) nanoparticles were employed. To design photocatalytic systems for practical and scalable use, the future research should be focused on deeper theoretical knowledge of mechanisms of light harvesting, ± charge separation and transport, surface biochemical reactions, semiconductor–liquid interactions, and reactor dynamics.

Identification of Leuconostoc species based on novel marker genes identified using real-time PCR via computational pangenome analysis.

Leuconostoc species are important microorganisms in food fermentation but also cause food spoilage. Although these species are commercially important, their taxonomy is still based on inaccurate identification methods. Here, we used computational pangenome analysis to develop a real-time PCR-based method for identifying and differentiating the 12 major Leuconostoc species found in food. Analysis of pan and core-genome phylogenies showed clustering of strains into 12 distinct groups according to the species. Pangenome analysis of 130 Leuconostoc genomes from these 12 species enabled the identification of each species-specific gene. In silico testing of the species-specific genes against 143 publicly available Leuconostoc and 100 other lactic acid bacterial genomes showed that all the assays had 100% inclusivity/exclusivity. We also verified the specificity for each primer pair targeting each specific gene using 23 target and 124 non-target strains and found high specificity (100%). The sensitivity of the real-time PCR method was 102 colony forming units (CFUs)/ml in pure culture and spiked food samples. All standard curves showed good linear correlations, with an R2 value of ≥0.996, suggesting that screened targets have good specificity and strong anti-interference ability from food sample matrices and non-target strains. The real-time PCR method can be potentially used to determine the taxonomic status and identify the Leuconostoc species in foods.

Efficacy of emerging technologies in addressing reductive dechlorination for environmental bioremediation: A review

Reductive dechlorination is a core pathway of chlorination in an anaerobic environment, which can be carried out by fermentative, methanogenic, iron and sulfate-reducing microorganisms. The present review showed the different metabolic ways of microbes with the emphasis on the anaerobic microbial dechlorination (including chemical, biological and nanotechnology-based strategies), that have been employed to mitigate the chlorinated pollutants. Chemical and nanomaterial science has made substantial advancement in several aspects of dechlorination over the past two decades, providing information about the process and the outcome of the reaction. However, these chemical processes are expensive to start with and pose ecological hazards. So, extensive research has been done to come up with eco-friendly biological alternatives). Under anaerobic conditions, dehalorespiring bacteria are capable of dechlorinating chloroethenes by mediating a stepwise replacement of chlorine with hydrogen resulting in the sequential conversion of perchloroethylene (PCE) to trichloroethylene (TCE), dichloroethylene (DCE) isomers, vinyl chloride (VC), and finally, ethane. Among many dehalorespiring bacterial isolates, only a few strains of the genus Dehalococcoides completely converted the chloroethenes to nontoxic ethane. In the paper we will, therefore, focus on this Dehalococcoides spp. Several factors influence the dechlorination activity between different dehalogenating bacteria. The vcrA and bvcA genes dechlorinate VC into ethene, which are essential for complete dechlorination. These pathways offer understanding of potential bioremediation of chlorinated aliphatic or aromatic compounds by Dehalococcoides with the likelihood of highly effective bioremediation.