Indigenous Microorganisms Research Articles

The impact of indigenous microorganisms on coal flotation: A new perspective on water consumption

Coal preparation plants are devoted to finding new strategies for reducing fresh water consumption, however, rarely taking consideration on slurry microorganisms. The impact of the abundant microorganisms on coal flotation, especially the isolated indigenous bacteria Bacillus sp. QX4 was systematically investigated in this study. Orthogonal experiments involved in parameters of concentration of microorganisms, collector and frother were conducted. The response surface analysis showed that the concentration of microorganisms was the main factor affecting flotation recovery and water consumption. With the amount of microorganisms increased from 105 to 108 cells/ml, clean coal yield decreased by 15 %, and water consumption increased by as high as 30 %. The characterization of the coal showed that the attachment of microorganisms increased the number of oxygen-containing functional groups onto the coal surface, and the contact angle of coal decreased from 79.5°to 56.6°. In addition, the net negative zeta potential decreased after microorganism addition, which improved the froth stability and weakened the coal’s attachment to the collector molecules. Further evaluation showed that the transfer of water reduced the calorific value of the clean coal by about 500 kcal/kg while increasing the carbon emission during combustion by about 5.9 %. This study provides a new perspective on the reverse impact of indigenous microorganisms on fresh water consumption and flotation product in coal flotation, which can potentially help efficient operation involved in optimizing water management of coal preparation plants.

Characterization and morphological study of microbes in treated palm oil mill effluents

Palm oil mill effluent (POME) is wastewater generated by palm oil milling. Due to its extremely polluting qualities, it must be treated before being discharged into the water course. This study was aimed to evaluate the bacterial growth of raw and treated POME as well as identifying indigenous microorganisms by determining the morphological characteristics of bacteria that were found in the POME. The bacterial growth was identified by bacterial enumeration of colony forming units (CFU). Besides, the morphological identification of bacteria was determined by using gram staining. The results show the best bacterial growth curve is from serial dilution factor of 10-6 with a total of 2.24 x 10-6 CFU/mL in raw POME and optimum growth on day seven. While for the treated POME, the total is 1.97 x 10-6 CFU/mL and recorded the optimum growth on day ten of incubation. The growth curve indicates the number of colonies in raw POME is higher than treated POME. It concluded that treated POME still has the bacteria although it has been treated. Apart from that, from the morphological identification by gram staining, the bacteria were Bacillus cereus, Bacillus subtilis, Staphylococcus aureus and Micrococcus luteus. From a gram staining, this research obtained all gram positive in purple colour from the POME samples. Two of them in treated POME were in Bacillus shape while the other two from raw and treated POME were in coccus shape, respectively.

Electron transfer by ion conductance in a soil bioelectric field

The efficacy of electron transfer determines the performance of soil microbial electrochemical systems (MESs). Ion conductance is an important endogenous route of electron transfer for the soil, yet its efficacy is unclear. Under the bioelectric field force generated in situ by indigenous soil microorganisms, dominant cations (Na+ and Mg2+) and anions (Cl− and SO42−) were all transported to the cathode in soil MESs. Furthermore, the same valence state of ions exhibited different and even opposite effects on ion conductance according to the work done by the bioelectric field force over time, e.g., Na+ and K+. Based on charges carried by migrated ions, we demonstrated that ion conductance was the main route of electron transfer in a soil MES, even for treatments with conductive magnetite and haematite. In contrast, electron shuttles contributed predominantly to electron transfer in ferrihydrite treatment. This was also supported by the characteristics of the charge transfer resistance and ohmic resistance according to the redundancy analysis with interpretation degrees of 93.96–94.25 %. Overall, this study provides profound insight into electron transfer by ion conductance in soil bioelectrochemical technology.

Characterization of Antagonist Potential of Selected Compost Bacterial Isolates (CBI) against Plant and Human Pathogens

Several fecal and enteric pathogens are present within the primary organic raw materials that are introduced to compost piles. These pathogens may compete with the existing microbiota and limit their efficiency, yielding only partial decomposition of the final compost. These pathogens also affect the process kinetics and persist in the final compost or may even regrow as a result of the declining effect of indigenous antagonistic micro-organisms. In this work, 11 indigenous bacterial isolates were selected from compost piles that were constructed from different percentages of comingled primary organic raw materials. Enzymatic, biochemical, and genetic characterization profiling of these strains was fulfilled. The top hits supplied by GenBank proved the genetic diversity of these strains, which belonged to 6 different families. This diversity, applied also at enzymatic and biochemical levels, showed the different degradation patterns of amino acids, carbohydrates, hormones, and proteins. CBI2 has been shown to be the most active isolate in the degradation of the different types of hormones and proteins from dairy products but lacks the enzymes needed for the degradation of ammonia into nitrogen. The antagonistic potential of recuperated secondary metabolites proved the total inhibition of all strains against Fusarium oxysporum and no growth limitation against Botrytis cinerea. Only the secondary metabolites of CBI1, CBI5, and CBI9 isolates showed inhibitory activity against Salmonella Typhimurium and Escherichia coli, whereas only those of CBI6 and CBI8 inhibited the growth of Salmonella Typhimurium and Listeria monocytogenes accordingly. From that finding, these strains are considered pioneering, with high potential to ensure both the efficient degradation of organic matter and the elimination of existing pathogens when applied to compost piles.

Metagenomic insights into the influence of thallium spill on sediment microbial community

Thallium (Tl) is an extremely toxic metal. The release of Tl into the natural environment can pose a potential threat to organisms. So far, information about the impact of Tl on indigenous microorganisms is still very limited. In addition, there has been no report on how sudden Tl spill influences the structure and function of the microbial community. Therefore, this study explored the response of river sediment microbiome to a Tl spill. Residual T1 in the sediment significantly decreased bacterial community diversity. The increase in the abundance of Bacteroidetes in all Tl- impacted sediments suggested the advantage of Bacteroidetes to resist Tl pressure. Under T1 stress, microbial genes related to carbon fixation and gene cysH participating in assimilatory sulfate reduction were down-regulated, while genes related to nitrogen cycling were up-regulated. After T1 spill, increase in both metal resistance genes (MRGs) and antibiotic resistance genes (ARGs) was observed in Tl-impacted sediments. Moreover, the abundance of MRGs and ARGs was significantly correlated with sediment Tl concentration, implying the positive effect of Tl contamination on the proliferation of these resistance genes. Procrustes analysis suggested a significant congruence between profiles of MRGs and bacterial communities. Through LEfSe and co-occurrence network analysis, Trichococcus, Polaromonas, and Arenimonas were identified to be tolerant and resistant to Tl pollution. The colocalization analysis of contigs indicated the co-effects of selection and transfer for MRGs/ARGs were important reasons for the increase in the microbial resistance in Tl-impacted sediments. This study added new insights into the effect of Tl spill on microbial community and highlighted the role of heavy metal spill in the increase of both heavy metal and antibiotic resistance genes.

Hydrocarbons removal and microbial community succession in petroleum-contaminated soil under hydrogen peroxide treatment.

Chemical oxidation as a pretreatment step coupled with bioremediation for petroleum-contaminated soil may pose serious impacts on indigenous microorganisms and the available nutrients. Petroleum-contaminated soil were treated by hydrogen peroxide (H2O2) at initial concentrations of 105mM (HH), 21mM (HL), and 105mM in three equal amounts (HT) without adding any external catalyst. The contents of total petroleum hydrocarbons (TPH) and dissolved nutrients (total organic compounds, nitrogen, and phosphate), and the indigenous bacteria community succession (analyzed by high-throughput sequencing of 16S rDNA) were investigated over 50days. Compared to the control treatment without H2O2 addition, H2O2 treatments for the petroleum-contaminated soil significantly promoted the TPH removal especially in the first 4days and impacted the contents of dissolved nutrients. Both of chemical oxidation and nutrients contributed to microbial community structure changes in alpha diversity. Although the soil microbial community structure had undergone significant changes after different chemical oxidation pretreatments, Firmicutes, Proteobacteria, Gemmatimonadetes, and Actinobacteria were the main bacterial phyla. Compared with adding H2O2 at one time, H2O2 added in stepwise was beneficial to indigenous bacterial diversity recovery and TPH removal. H2O2 oxidation treatments showed a great influence on the microbial community structures in the start-up stage, while recovery time rather than the oxidation treatments presented greater effects on the composition of the microbial community structure with the incubation time extended. Therefore, adding H2O2 as pretreatment for petroleum-contaminated soil showed little effect on the structure of soil indigenous microbial community from a long-term scale, and was conducive to the continuous removal of TPH by indigenous microorganisms.

Comparing the indigenous microorganism system in typical petroleum-contaminated groundwater

The environmental conditions at a contaminated site will impact on the indigenous microbial communities, with implications for the removal of pollutants. An analysis of the characteristics of microbial communities in petroleum-contaminated groundwater can give insights into the relationships between microbial community and environmental factors, and provide guidance about how microbes can be used to remediate and regulate petroleum-contaminated groundwater. This study focuses on two petroleum-contaminated sites in northeast China, the physico-chemical-biological changes in petroleum-contaminated groundwater were analyzed, the response relationship between hydro-chemical indicators and microbial communities was characterized, and the bioindicator that can reflect the petroleum contamination status were established for environmental monitoring and management. The results showed that Proteobacteria was the dominant bacteria in petroleum-contaminated groundwater, with a relative abundance of 42.45%–91.19%. pH, TDS, DO, NO3−, NO2−, SO42−, NH4+, Al, and Mn have significant effects on microbial community. The effect of petroleum pollutants on microbial communities is not only related to the concentration and composition of the pollutants themselves, but also could indirectly affect microbial communities by changing the content of inorganic electron acceptor components such as iron, manganese, sulfate and nitrate in groundwater, and this indirect effect is significantly greater than the direct impact of pollutants on microbial communities. In petroleum-contaminated groundwater, the dominant genera (Polaromonas, Caulobacter) and microbial metabolic functions (methanol oxidation, methylotrophy, ureolysis, and reductive biosynthesis) of the indigenous microbial community can be used as bioindicators to indicate petroleum contamination status. The higher abundance of these bioindicators in petroleum-contaminated groundwater, the more serious petroleum pollution in groundwater.

Metagenomics analysis of the polymeric and monomeric phenolic dynamic changes related to the indigenous bacteria of black tea spontaneous fermentation

Spontaneous fermentation during black tea production involves several reactions, including the oxidation of phenolic compounds. This process has usually been studied without considering the potential involvement of indigenous tea microorganisms. This work utilised a metagenomic technique targeting bacterial 16S rRNA genes and evaluated the profile of phenolic compounds generated during the production of black tea. The resulting data were used to develop correlational and predictive functional analyses related to bacterial dynamics and the syntheses of various phenolic compounds. In particular, the genera Methylobacterium and Devosia were correlated with gallic acid and quercetin. Concurrently, the genera Sphingomonas, Chryseobacterium and Aureimonas were correlated with kaempferol, theaflavins, thearubigins and theabrownins. These results, supported by predicted functional analysis based on 16S rRNA genes associated with phenolic compounds, indicated that yfiH (polyphenol oxidase) and katG (catalase-peroxidase) are likely the dominant genes of the bacterial community involved in the black tea production process. This research suggests that bacteria could potentially contribute to the production process of black tea.

Guided by the principles of microbiome engineering: Accomplishments and perspectives for environmental use.

Although the accomplishments of microbiome engineering highlight its significance for the targeted manipulation of microbial communities, knowledge and technical gaps still limit the applications of microbiome engineering in biotechnology, especially for environmental use. Addressing the environmental challenges of refractory pollutants and fluctuating environmental conditions requires an adequate understanding of the theoretical achievements and practical applications of microbiome engineering. Here, we review recent cutting-edge studies on microbiome engineering strategies and their classical applications in bioremediation. Moreover, a framework is summarized for combining both top-down and bottom-up approaches in microbiome engineering towardimproved applications. A strategy to engineer microbiomes for environmental use, which avoids the build-up of toxic intermediates that pose a risk to human health, is suggested. We anticipate that the highlighted framework and strategy will be beneficial for engineering microbiomes to address difficult environmental challenges such as degrading multiple refractory pollutants and sustain the performance of engineered microbiomes in situ with indigenous microorganisms under fluctuating conditions.

Quantitative PCR reveals the frequency and distribution of 3 indigenous yeast species across a range of specialty cheeses.

Indigenous microorganisms are important components of the complex ecosystem of many dairy foods including cheeses, and they are potential contributors to the development of a specific cheese's sensory properties. Among these indigenous microorganisms are the yeasts Cyberlindnera jadinii, Pichia kudriavzevii, and Kazachstania servazzii, which were previously detected using traditional microbiological methods in both raw milk and some artisanal specialty cheeses produced in the province of Québec, Canada. However, their levels across different cheese varieties are unknown. A highly specific and sensitive real-time quantitative PCR assay was developed to quantitate these yeast species in a variety of specialty cheeses (bloomy-rind, washed-rind, and natural-rind cheeses from raw, thermized, and pasteurized milks). The specificity of the quantitative PCR assay was validated, and it showed no cross-amplification with 11 other fungal microorganisms usually found in bloomy-rind and washed-rind cheeses. Cyberlindnera jadinii and P. kudriavzevii were found in the majority of the cheeses analyzed (25 of 29 and 24 of 29 cheeses, respectively) in concentrations up to 104 to 108 gene copies/g in the cheese cores, which are considered oxygen-poor environments, and 101 to 104 gene copies/cm2 in the rind. However, their high abundance was not observed in the same samples. Whereas C. jadinii was present and dominant in all core and rind samples, P. kudriavzevii was mostly present in cheese cores. In contrast, K. servazzii was present in the rinds of only 2 cheeses, in concentrations ranging from 101 to 103 gene copies/cm2, and in 1 cheese core at 105 gene copies/g. Thus, in the ecosystems of specialty cheeses, indigenous yeasts are highly frequent but variable, with certain species selectively present in specific varieties. These results shed light on some indigenous yeasts that establish during the ripening of specialty cheeses.

Optimized strategy valorizing unautoclaved cottonseed hull as ruminant alternative feeds via solid-state fermentation: Detoxifying polyphenols, restraining hazardous microflora and antibiotic-resistance gene hosts

Cottonseed hull (CSH), typical agro-industrial byproduct, is widely valorized as ruminant alternative feeds, but many constraints including extensive anti-nutritional factors and indigenous hazardous microflora are still reasonably unsolved. This study proposed a novel strategy that valorizes unautoclaved CSH as ruminant alternative feeds via solid-state fermentation (SSF), where feasibility and microbial mechanism were roundly investigated. The SSF of raw CSH (R group, proposed in this study) was compared with autoclaved CSH (M group, prevalent strategy) based on physicochemical properties, chemical functionalities, and superficial structures. Compared to M group, R group though has exhibited near detoxification effect of polyphenols (81.7% free gossypol (FG) and 62.2% condensed tannin (CT), both below threshold values) after SSF, yet the accumulation of crude protein and fat has been higher (109.3 and 51.0 g/kg dry matter, respectively). Metagenomic analyses indicated the indigenous hazardous microorganisms and antibiotic-resistance genes were prevented from amplification in R group. More importantly, Pleurotus was the keystone contributor to functional gene sets of degrading polyphenols (FG and CT) and lignin during SSF in R group; furthermore, CAZyme gene sets associated with polysaccharide degradation were primarily derived from bacterial communities ( Cellulomonas , and Stenotrophomonas , et al.). Ultimately, microbial SSF of raw CSH can be a feasible strategy with minimum facility investment and energy consumption, thus expediting CSH valorization in feedstock industries and the sustainable bio-economy in developing countries. • SSF valorizing raw cottonseed hull (CSH) as ruminant alternative feeds is feasible. • This strategy facilitates the sustainable bio-economy. • Polyphenols content declined to safe threshold during SSF. • SSF is resilient to animal pathogens and the transfer of antibiotic resistance genes. • Functional gene set about polyphenol and lignin degradation is traced from Pleurotus .

A starch-based controlled-release targeted nutrient agent to stimulate the activity of volatile chlorinated hydrocarbon-degrading indigenous microflora present in groundwater

Volatile chlorinated hydrocarbons (VCHs) contaminated groundwater has a low indigenous microorganism population, and lack of nutrient substrates involved in degradation reactions, resulting in a weak natural remediation ability of groundwater ecosystems. In this study, based on the principle of degradation of VCHs by indigenous microorganisms in groundwater, and combined with biostimulation and controlled-release technology, we developed a starch-based encapsulated targeted bionutrient (YH-1) with easy uptake, good stability, controllable slow-release migration, and long timeliness for the remediation of groundwater contaminated by VCHs by indigenous microorganisms. The results showed that YH-1 is easily absorbed by microorganisms and can rapidly initiate itself to stimulate the microbial degradation of VCHs, and the degradation rate of various VCH components within 7 days was 82.38–92.38 %. The release rate of nutrient components in YH-1 increases with increasing VCH concentrations in groundwater; this could effectively prolong the action time of nutrient components, while also improving the degradation efficiency of pollutants with a sustained effect of more than 15 days. Simultaneously, owing to the fluidity, water solubility, and biodegradability of YH-1 in lithologic media, YH-1 injection did not cause blockage of the lithologic media in the aquifer. Through YH-1 stimulation, indigenous microorganisms grew rapidly in the underground environment, the diversity of microbial communities and the total number of species increased, and the correlation between genera strengthened. Simultaneously, YH-1 improved the ability of microbial community to convert inorganic electron donors/acceptors, thereby strengthening the co-metabolic mechanism between microorganisms. Additionally, there was a significant increase in the percentage of many microorganisms (e.g., Sphingomonas, Janthinobacterium, Duganella, etc.) that mediated the reductive dechlorination process and were redox inorganic electron donors/acceptors. This was conducive to the reductive dechlorination process of VCHs and achieved the efficient degradation of VCHs.

Mycobacteriaceae Mineralizes Micropolyethylene in Riverine Ecosystems.

Microplastic (MP) contamination is a serious global environmental problem. Plastic contamination has attracted extensive attention during the past decades. While physiochemical weathering may influence the properties of MPs, biodegradation by microorganisms could ultimately mineralize plastics into CO2. Compared to the well-studied marine ecosystems, the MP biodegradation process in riverine ecosystems, however, is less understood. The current study focuses on the MP biodegradation in one of the world's most plastic contaminated rivers, Pearl River, using micropolyethylene (mPE) as a model substrate. Mineralization of 13C-labeled mPE into 13CO2 provided direct evidence of mPE biodegradation by indigenous microorganisms. Several Actinobacteriota genera were identified as putative mPE degraders. Furthermore, two Mycobacteriaceae isolates related to the putative mPE degraders, Mycobacterium sp. mPE3 and Nocardia sp. mPE12, were retrieved, and their ability to mineralize 13C-mPE into 13CO2 was confirmed. Pangenomic analysis reveals that the genes related to the proposed mPE biodegradation pathway are shared by members of Mycobacteriaceae. While both Mycobacterium and Nocardia are known for their pathogenicity, these populations on the plastisphere in this study were likely nonpathogenic as they lacked virulence factors. The current study provided direct evidence for MP mineralization by indigenous biodegraders and predicted their biodegradation pathway, which may be harnessed to improve bioremediation of MPs in urban rivers.

Pollutant removal from cheese processing effluent using effective indigenous natural scavengers.

The goal of this study was to come up with an efficient method for treating cheese production wastewater. Because the effluent has a higher concentration of organic and inorganic materials, the indigenous microbial treatment process was used to effectively remove total dissolved solids (TDS), chemical oxygen demand (COD), and color without the addition of any nutrients. The indigenous microorganisms were tested for color, TDS, and COD elimination by growing them in "nutrient broth medium" loaded with different amounts of cheese effluent. The isolates were identified by 16S rRNA sequencing, and the results revealed that strain 1 was Enterobacter cloacae, strain 2 was Lactococcus garvieae, and strains 3 and 4 were Bacillus cereus and Bacillus mycoides, respectively. After 36h of incubation, the data were evaluated. Among all the microbes, E. cloacae reduced TDS and COD from the effluent the most (80 ± 0.2% and 87 ± 0.4% COD, respectively). When compared to individual species, consortia were more efficient (86 ± 0.2% TDS and 90 ± 0.3% COD). On treatment, the correlation coefficient "r" for TDS and COD elimination was found to be 1, resulting in a positive linear connection. The current study suggests that microbial therapies are both effective and environmentally beneficial.

The Amount of the Rare Sugar Tagatose on Tomato Leaves Decreases after Spray Application under Greenhouse Conditions.

Tagatose is a rare sugar that suppresses plant diseases, such as late blight of tomato, caused by Phytophthora infestans. Tagatose can be metabolized by some microorganisms and no information is available on its persistence on tomato leaves. The aim of this study was to assess the persistence of tagatose on tomato leaves under commercial greenhouse conditions. The amount of tagatose on tomato leaves and the inhibitory activity against P. infestans decreased seven days after spray application in the absence of rain wash-off. Potential tagatose-degrading bacteria were isolated from tomato leaves, and they belonged to Acinetobacter sp., Bacillus sp., Comamonas sp., Enterobacter sp., Methylobacterium sp., Microbacterium sp., Pantoea sp., Plantibacter sp., Pseudomonas sp., Ralstonia sp., Rhodococcus sp., Sphingobium sp., and Sphingomonas sp. Thus, indigenous phyllosphere microorganisms could partially metabolize tagatose laid on plant leaves after spray application, reducing the persistence of this fungal inhibitor on tomato leaves.

Finding the best combination of autochthonous microorganisms with the most effective biosorption ability for heavy metals removal from wastewater.

The presence of heavy metals (HMs) in the environment represents a serious environmental problem. In this regard, this work was conceived with the aim of finding, among indigenous microorganisms, the species and their combinations with the best biosorption activity for the following HMs: zinc, lead, cadmium, copper, and nickel. The experiment was carried out in several steps: (1) isolation and identification of microbial strains from the Central Effluent Treatment Plant’s wastewater; (2) studying the interaction of microorganisms and the ability to form biofilms in 96-well plates; (3) testing the resistance of biofilms to HMs; (4) testing the growth of biofilms on AMB media carriers in the presence of HMS; and (5) biosorption assay. The selected strains used in this study were: Enterobacter cloacae, Klebsiella oxytoca, Serratia odorifera, and Saccharomyces cerevisiae. The best biofilm producers in control medium were K. oxytoca/S. odorifera (KS), followed by K. oxytoca/S. odorifera/S. cerevisiae (KSC), and E. cloacae/K. oxytoca/S. odorifera (EKS) after 10 days of incubation. Mixed cultures composed of three species showed the highest resistance to the presence of all tested metals. The best biosorption capacity was shown by KSC for Cu2+ (99.18%), followed by EKS for Pb2+ (99.14%) and Cd2+ (99.03%), K. oxytoca for Ni2+ (98.47%), and E. cloacae for Zn2+ (98.06%). This research offers a novel approach to using mixed biofilms for heavy metal removal processes as well as its potential application in the bioremediation of wastewater.

Synergistic effects of microorganisms and passivation materials on the growth and Cd uptake of coriander (Coriandrum sativum L.) in Cd-contaminated soils

Cadmium (Cd) contamination in agricultural soils has become a serious issue owing to its high toxicity to human health via food chain. Appropriate remediation strategies of combining rhizosphere microbes and amendments are strongly advisable for the safe production of crops in contaminated soil to mitigate heavy metal uptake and enhance crop yield. A pot experiment was established to investigate the combined effect of Si–Ca–K–Mg (SCKM) amendment, biochar, arbuscular mycorrhizal fungi (AMF), and indigenous microorganisms on growth, nutrient uptake, and Cd concentration of coriander (Coriandrum sativum L.), as well as soil Cd immobilisation in two acidic soils. The results showed that the application of SCKM amendment and biochar alone significantly reduced Cd concentrations in the shoots and roots of coriander in the two soils. Regardless of amendments, AMF inoculation alone and indigenous microorganisms were more effective at inducing soil alkalinisation and Cd immobilisation in high-Cd soil (1.08 mg/kg). AMF inoculation and SCKM amendment together had a synergistic effect on increasing the biomass and P, K, Mg, and Ca contents of plant tissues in low-Cd soil (0.289 mg/kg). Meanwhile, adding biochar together with AMF inoculation drastically reduced shoot and root Cd concentrations of coriander in low-Cd soil. The synergistic effect of biochar and indigenous microorganisms was significant in high-Cd soil, with a reduction in the concentration of shoot Cd, root Cd, and soil diethylenetriaminepentaacetic acid (DTPA) extractable Cd, respectively. These results suggest that microorganisms in combination with SCKM amendment and biochar application have a potentially additive effect on production and on the reduction in Cd uptake by coriander, as well as mitigating the releases of heavy metals and the associated environmental impact from abandoned mine tailings.

Environmental Determination of Indigenous Bifidobacteria of the Human Intestine.

The environmental determination of indigenous (constantly present) bifidobacteria of the human large intestine is considered in this review. Environmental determination (from the Latin determinere, "Idetermine") is understood as a set of natural phenomena of a habitat (biotope) that determine the role of indigenous microorganisms in the microbiocenosis. Using the symbiotic approach, an attempt is made to identify the environmental conditions for the habitat of bifidobacteria and their physiological effects in the microsymbiocenosis. The features of indigenous bifidobacteria in terms of their nature have been established: evolutionary-genetic (phylogenetic remoteness, genome conservation, metabolic specialization), biochemical (lysozyme resistance, constitutive acetate production), and physiological (microbial "friend-foe" identification, immunoregulation), which are important in adaptation (persistence) and the provision of mutualistic effects and stability of the bifidoflora in the population.

Stress response characteristics of indigenous microorganisms in aromatic-hydrocarbons-contaminated groundwater in the cold regions of Northeast China

The resistance mechanism of microbial communities in contaminated groundwater under combined stresses of aromatic hydrocarbons (AHs), NH4+, and Fe–Mn exceeding standard levels was studied in an abandoned oil depot in Northeast China. The response of environmental parameters and microbial communities under different pollution levels in the study area was discussed, and microscopic experiments were conducted using background groundwater with different AHs concentrations. The results showed that indigenous microbial community were significantly affected by environmental factors, including pH, TH, CODMn, TFe, Cr (VI), NH4+, NO3-, and SO42-. AHs likely had a limited influence on microbial communities, mainly causing indirect changes in the microbial community structure by altering the electron donor/acceptor (mainly Fe, Mn, NO3-, NO2-, NH4+, and SO42-) content in groundwater, and there was no linear effect of AHs content on the microbial community. In low- and medium-AHs-contaminated groundwater, the microbial diversity increased, whereas high AHs contents decreased the diversity of the microbial community. The microbial community had the strongest ability to metabolize AHs in the medium-AHs-contaminated groundwater. In the high-AHs-contaminated groundwater, microbial communities mainly degraded AHs through a complex co-metabolic mechanism due to the inhibitory effect caused by the high concentration of AHs, whereas in low-AHs-contaminated groundwater, microbial communities mainly caused a mutual transformation of inorganic electron donors/acceptors (mainly including N, S), and the microbial community’s ability to metabolize AHs was weak. In the high-AHs-contaminated groundwater, the microbial community resisted the inhibitory effect of AHs mainly via a series of resistance mechanisms, such as regulating their life processes, avoiding unfavorable environments, and enhancing their feedback to the external environment under high-AHs-contaminated conditions.

Bacterial degradation of bisphenol analogues: an overview.

Bisphenol A (BPA) is one of the most produced synthetic monomers in the world and is widespread in the environment. BPA was replaced by bisphenol analogues (BP) because of its adverse effects on life. Bacteria can degrade BPA and other bisphenol analogues (BP), diminishing their environmental concentrations. This study aimed to summarize the knowledge and contribute to future studies. In this review, we surveyed papers on bacterial degradation of twelve different bisphenol analogues published between 1987 and June 2022. A total of 102 original papers from PubMed and Google Scholar were selected for this review. Most of the studies (94.1%, n = 96) on bacterial degradation of bisphenol analogues focused on BPA, and then on bisphenol F (BPF), and bisphenol S (BPS). The number of studies on bacterial degradation of bisphenol analogues increased more than six times from 2000 (n = 2) to 2021 (n = 13). Indigenous microorganisms and the genera Sphingomonas, Sphingobium, and Cupriavidus could degrade several BP. However, few studies focussed on Cupriavidus. The acknowledgement of various aspects of BP bacterial biodegradation is vital for choosing the most suitable microorganisms for the bioremediation of a single BP or a mixture of BP.