16S rRNA Gene Sequence Research Articles

Reclassification of Streptomyces violarus (Artamonova and Krassilnikov 1960) Pridham 1970 as a Later Heterotypic Synonym of Streptomyces violaceus (Rossi Doria 1891) Waksman 1953 using a Polyphasic Approach.

The taxonomic relationship between Streptomyces violarus and Streptomyces violaceus was reevaluated using a polyphasic taxonomic approach in this work. Phylogenetic analysis based on 16S rRNA gene sequences indicated that Streptomyces violarus JCM 4534T was closely related to Streptomyces arenae ISP 5293T. However, phylogenetic analysis based on five house-keeping gene (atpD, gyrB, recA, rpoB and trpB) showed that the evolutionary neighbor of Streptomyces violarus JCM 4534T was Streptomyces violaceus CGMCC 4.1456T, suggesting that there was a close genetic relationship between these two strains. The average nucleotide identity and digital DNA-DNA hybridization values between them were 97.0 and 72.9%, respectively, greater than the 96.7 and 70% cut-off points recommended for delineating a Streptomyces species. This result indicated that they belonged to the same genomic species which was also verified by a comprehensive comparison of phenotypic and chemotaxonomic characteristics between Streptomyces violarus JCM 4534T and Streptomyces violaceus CGMCC 4.1456T. According to all these data and the rule of priority in nomenclature, it is proposed the Streptomyces violarus (Artamonova and Krassilnikov 1960) Pridham 1970 is a later heterotypic synonym of Streptomyces violaceus (Rossi Doria 1891) Waksman 1953. In addition, based on dDDH, Streptomyces violaceus and Streptomyces violarus are simultaneously designated as two different subspecies, i.e., Streptomyces violaceus subsp. violaceus and Streptomyces violaceus subsp. violarus.

Potentiality of Beneficial Microbe Bacillus siamensis GP-P8 for the Suppression of Anthracnose Pathogens and Pepper Plant Growth Promotion

This study was carried out to screen the antifungal activity against Colletotrichum acutatum, Colletotrichum dematium, and Colletotrichum coccodes. Bacterial isolate GP-P8 from pepper soil was found to be effective against the tested pathogens with an average inhibition rate of 70.7% in in vitro dual culture assays. 16S rRNA gene sequencing analysis result showed that the effective bacterial isolate as Bacillus siamensis. Biochemical characterization of GP-P8 was also performed. According to the results, protease and cellulose, siderophore production, phosphate solubilization, starch hydrolysis, and indole-3-acetic acid production were shown by the GP-P8. Using specific primers, genes involved in the production of antibiotics, such as iturin, fengycin, difficidin, bacilysin, bacillibactin, surfactin, macrolactin, and bacillaene were also detected in B. siamensis GP-P8. Identification and analysis of volatile organic compounds through solid phase microextraction/gas chromatography-mass spectrometry (SPME/GC-MS) revealed that acetoin and 2,3-butanediol were produced by isolate GP-P8. In vivo tests showed that GP-P8 significantly reduced the anthracnose disease caused by C. acutatum, and enhanced the growth of pepper plant. Reverse transcription polymerase chain reaction analysis of pepper fruits revealed that GP-P8 treated pepper plants showed increased expression of immune genes such as CaPR1, CaPR4, CaNPR1, CaMAPK4, CaJA2, and CaERF53. These results strongly suggest that GP-P8 could be a promising biocontrol agent against pepper anthracnose disease and possibly a pepper plant growth-promoting agent.

Flavobacterium rivulicola sp. nov., Isolated from a Freshwater Stream.

A Gram-strain-negative, aerobic, yellow-colored, non-motile, and rod-shaped bacterial strain, designated IMCC34852T, was isolated from a freshwater stream in the Republic of Korea. Cellular growth occurred at 10-37°C, pH 6.0-9.0, and with 0-0.5% (w/v) NaCl. The 16S rRNA gene sequence analysis showed that strain IMCC34852T belonged to the genus Flavobacterium and that the strain was most closely related to F. cheonhonense ARSA-15T (97.6%), F. buctense T7T (96.7%), F. silvisoli RD-2-33T (96.1%), and F. paronense KNUS1T (96.1%). The whole-genome sequence of strain IMCC34852T was 3.2 Mbp in size, with a DNA G + C content 37.3%. The average nucleotide identities (ANI) and digital DNA-DNA hybridization (dDDH) values between strain IMCC34852T and its related species were all below 79.8% and 22.7%, respectively, which are significantly lower than the thresholds of 95% for ANI and 70% for DDH for species delineation. The major respiratory quinone of strain IMCC34852T was menaquinone-6 (MK-6) and the predominant cellular fatty acids were iso-C15:0 (32.6%), iso-C16:0 (11.7%), iso-C15:1 G (10.3%), and iso-C14:0 (6.7%). The major polar lipids of the strain were phosphatidylethanolamine, two unidentified aminolipids and six unidentified lipids. Based on these results, it was concluded that strain IMCC34852T represents a novel species in the genus Flavobacterium, for which the name Flavobacterium rivulicola sp. nov is proposed. The type strain of the proposed novel species is IMCC34852T (= KACC 23133T = KCTC 82066T = NBRC 114419T).

Changes in Soil Microbial Communities Induced by Biodegradable and Polyethylene Mulch Residues Under Three Different Temperatures

Mulching is a common method increasing crop yield and achieving out-of-season production; nevertheless, their removal poses a significant environmental danger. In this scenario, the use of biodegradable plastic mulches comes up as a solution to increase the sustainability of this practice, as they can be tilled in soil without risk for the environment. In this context, it is important to study the microbial response to this practice, considering their direct involvement in plastic biodegradation. This study evaluated the biodegradation of three commercial mulch residues: one conventional non-biodegradable mulch versus two biodegradable ones (white and black compostable Mater-Bi mulches). The experiment was conducted under three incubation temperatures (room temperature 20–25 °C, 30 °C, and 45 °C) for a 6-month trial using fallow agricultural soil. Soil without plastic mulch residues was used as a control. White mater-bi biodegradable mulch residues showed higher degradation rates up to 88.90% at 30 °C, and up to 69.15% at room temperature. Furthermore, incubation at 45 °C determines the absence of degradation for all types of mulch considered. Moreover, bacterial alpha diversity was primarily influenced by plastic type and temperature, while fungal populations were mainly affected by temperature. Beta diversity was impacted by all experimental variables. Predicted functional genes crucial for degrading complex substrates, including those encoding hydrolases, cutinases, cellobiosidases, and lipases, were derived from 16S rRNA gene sequencing data. Cluster analysis based on predicted enzyme-encoding gene abundance revealed two clusters, mainly linked to sampling time. Finally, core microbiome analysis identified dominant bacterial and fungal taxa in various soil-plastic ecosystems during degradation, pinpointing species potentially involved in plastic breakdown. The present study allows an assessment of how different temperatures affect the degradation of mulch residues in soil, providing important insights for different climatic growing zones. It also fills a gap in the literature by directly comparing the effects of biodegradable and polyethylene mulches on soil microbial communities.

The Improving Effects of Probiotic-Added Pollen Substitute Diets on the Gut Microbiota and Individual Health of Honey Bee (Apis mellifera L.)

Honey bee (Apis mellifera L.) health is crucial for honey bee products and effective pollination, and it is closely associated with gut bacteria. Various factors such as reduced habitat, temperature, disease, and diet affect the health of honey bees by disturbing the homeostasis of the gut microbiota. In this study, high-throughput 16S rRNA gene sequencing was used to analyze the gut microbiota of honey bees subjected to seven diets over 5 days. Lactobacillus dominated the microbiota in all diets. Cage experiments (consumption, head protein content, and vitellogenin gene expression level) were conducted to verify the effect of the diet. Through a heatmap, the Diet2 (probiotic-supplemented) group was clustered together with the Beebread and honey group, showing high consumption (177.50 ± 26.16 mg/bee), moderately higher survival duration (29.00 ± 2.83 days), protein content in the head (312.62 ± 28.71 µg/mL), and diet digestibility (48.41 ± 1.90%). Additionally, we analyzed the correlation between gut microbiota and health-related indicators in honey bees fed each diet. Based on the overall results, we identified that probiotic-supplemented diets increased gut microbiota diversity and positively affected the overall health of individual honey bees.

Microvirga sesbaniae sp. nov. and Microvirga yunnanensis sp. nov., Pink-Pigmented Bacteria Isolated from Root Nodules of Sesbania cannabina (Retz.) Poir.

Four pigment-producing rhizobial strains nodulating Sesbania cannabina (Retz.) Poir. formed a unique group in genus Microvirga in the phylogeny of a 16S rRNA gene and five housekeeping genes (gyrB, recA, dnaK, glnA, and atpD) in a genome analysis, phenotypic characteristics analysis, and chemotaxonomic analysis. These four strains shared as high as 99.3% similarity with Microvirga tunisiensis LmiM8T in the 16S rRNA gene sequence and, in an MLSA, were subdivided into two clusters, ANI (genome average nucleotide) and dDDH (digital DNA–DNA hybridization) which shared sequence similarities lower than the species thresholds with each other and with the reference strains for related Microvirga species. The polar lipids elucidated that phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), and cardiolipin were the main components for strain SWF67558T and for strain HBU65207T, with the exception of PC. SWF67558T and HBU65207T strains had similar predominant cellular fatty acids, including C16:0, C18:0, summed feature 2, and summed feature8, but with different contents. In addition, all the four novel strains produced pink-pigment, and the main coloring material extract from strain SWF67558T was identified as zeaxanthin, which presented antioxidant ability and reduction power. With all the phylogenetic and phenotypic divergency, we proposed these pink-pigmented symbiotic bacteria as two novel species, named Microvirga sesbaniae sp. nov. and Microvirga yunnanensis sp. nov., with SWF67558T (=KCTC82331T=GDMCC1.2024T) and HBU65207T (=KCTC92125T=GDMCC1.2023T) as the type strains, respectively.

Collimonas rhizosphaerae sp. nov., a novel species isolated from the beech rhizosphere.

Bacterial strain H4R21T was isolated from beech rhizosphere soil sampled in the forest experimental site of Montiers (Meuse, France). It effectively weathers minerals, hydrolyses chitin and produces quorum sensing signal molecules. The strain is aerobic and Gram-stain-negative. Phylogenetic analysis based on its 16S rRNA gene sequence indicated that strain H4R21T belongs to the genus Collimonas with high sequence similarity to C. arenae Ter10T (99.38 %), C. fungivorans Ter6T(98.97 %), C. pratensis Ter91T (98.76 %), C. humicola RLT1W51T (98.46 %) and C. silvisoli RXD178 T (98.46 %), but less than 98 % similarity to other strains of the genus Collimonas. The predominant quinone in H4R21T is ubiquinone-8 (Q8). The major polar lipids are diphosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and lipid. The major fatty acids identified were C12 : 0, C12:0 3-OH, C16 : 0 and C17:0 cyclo. The digital DNA G+C content of the genomic DNA was 59.5 mol%. Furthermore, the strain could be clearly distinguished from its closely related type strains by a combination of phylogenomic and in silico DNA-DNA hybridization results, and phenotypic characteristics. Therefore, strain H4R21T represents a novel species within the genus Collimonas, for which the name Collimonas rhizosphaerae sp. nov. is proposed, with strain H4R21T (=CFBP 9203T=DSM 117599T) as the type strain.

Desertibaculum subflavum gen. nov., sp. nov., a novel member of the family Sneathiellaceae isolated from the Kumtag Desert soil.

A novel rod-shaped bacterium, designated as strain SYSU D60015T that formed yellowish colonies was isolated from a sandy soil collected from the Kumtag Desert in Xinjiang, China. Cells were Gram-stain-negative, oxidase-positive, catalase-negative and motile with a single polar flagellum. Growth optimum occurred between 28 and 37°C, pH 7.0 and with 0-0.5% (W/V) NaCl. The predominant cellular fatty acids (> 5%) were summed feature 8 (C18:1 ω7c and/or C18:1 ω6c), C19:0 cyclo ω8c, C18:1 ω7c 11-methyl and C16:0. The polar lipid profile contained one phosphatidylethanolamine, one diphosphatidylglycerol, one phosphatidylglycerol, one unidentified phospholipid, three unidentified aminolipids, two unidentified aminophospholipids and seven unidentified lipids. The only respiratory quinone was ubiquinone-10. Based on 16S rRNA gene sequence phylogenetic analysis, strain SYSU D60015T was found to form a distinct linage within the family Sneathiellaceae, and had 16S rRNA gene sequence similarities of 90.8% to Taonella mepensis H1T, and 90.2% to Ferrovibrio denitrificans S3T. The genome of SYSU D60015T was 5.66 Mb in size with 68.2% of DNA G + C content. The low digital DNA-DNA hybridization (dDDH, 18.0%), average nucleotide identity (ANI, 77.5%) and amino acid identity (AAI, 56.0%) values between SYSU D60015T and Ferrovibrio terrae K5T indicated that SYSU D60015T might represent a distinct genus. Based on the phylogenetic, phenotypic, chemotaxonomic and genomic data, we propose Desertibaculum subflavum gen. nov., sp. nov. as a novel species of a new genus within the family Sneathiellaceae. The type strain is SYSU D60015T (= NBRC 112952T = CGMCC 1.16256T).

Comparative analysis of cyanobacterial communities in gypsum outcrops: insights from sites in Israel and Poland.

Today, the biodiversity of endolithic microbial colonisations are only partly understood. In this study, we used a combination of molecular community metabarcoding using the 16S rRNA gene, light microscopy, CT-scan analysis, and Raman spectroscopy to describe gypsum endolithic communities in 2 sites-southern Poland and northern Israel. The obtained results have shown that despite different geographical areas, climatic conditions, and also physical features of colonized gypsum outcrops, both of these sites have remarkably similar microbial and pigment compositions. Cyanobacteria dominate both of the gypsum habitats, followed by Chloroflexi and Pseudomonadota. Among cyanobacteria, Thermosynechococcaceae were more abundant in Israel while Chroococcidiopsidaceae in Poland. Interestingly, no Gloeobacteraceae sequences have been found in Poland, only in Israel. Some of the obtained 16S rRNA gene sequences of cyanobacteria matched previously detected sequences from endolithic communities in various substrates and geographical regions, supporting the hypothesis of global metacommunity, but more data are still needed. Using Raman spectroscopy, cyanobacterial UV-screening pigments-scytonemin and gloeocapsin have been detected alongside carotenoids, chlorophyll a and melanin. These pigments can serve as potential biomarkers for basic taxonomic identification of cyanobacteria. Overall, this study provides more insight into the diversity of cyanobacterial endolithic colonisations in gypsum across different areas.

Comparison between 16S rRNA and shotgun sequencing in colorectal cancer, advanced colorectal lesions, and healthy human gut microbiota

BackgroundGut dysbiosis has been associated with colorectal cancer (CRC), the third most prevalent cancer in the world. This study compares microbiota taxonomic and abundance results obtained by 16S rRNA gene sequencing (16S) and whole shotgun metagenomic sequencing to investigate their reliability for bacteria profiling. The experimental design included 156 human stool samples from healthy controls, advanced (high-risk) colorectal lesion patients (HRL), and CRC cases, with each sample sequenced using both 16S and shotgun methods. We thoroughly compared both sequencing technologies at the species, genus, and family annotation levels, the abundance differences in these taxa, sparsity, alpha and beta diversities, ability to train prediction models, and the similarity of the microbial signature derived from these models.ResultsAs expected, the results showed that 16S detects only part of the gut microbiota community revealed by shotgun, although some genera were only profiled by 16S. The 16S abundance data was sparser and exhibited lower alpha diversity. In lower taxonomic ranks, shotgun and 16S highly differed, partially due to a disagreement in reference databases. When considering only shared taxa, the abundance was positively correlated between the two strategies. We also found a moderate correlation between the shotgun and 16S alpha-diversity measures, as well as their PCoAs. Regarding the machine learning models, only some of the shotgun models showed some degree of predictive power in an independent test set, but we could not demonstrate a clear superiority of one technology over the other. Microbial signatures from both sequencing techniques revealed taxa previously associated with CRC development, e.g., Parvimonas micra.ConclusionsShotgun and 16S sequencing provide two different lenses to examine microbial communities. While we have demonstrated that they can unravel common patterns (including microbial signatures), shotgun often gives a more detailed snapshot than 16S, both in depth and breadth. Instead, 16S will tend to show only part of the picture, giving greater weight to dominant bacteria in a sample. Therefore, we recommend choosing one or another sequencing technique before launching a study. Specifically, shotgun sequencing is preferred for stool microbiome samples and in-depth analyses, while 16S is more suitable for tissue samples and studies with targeted aims.

The Role of Infant Gut Microbiota Modulation by Perinatal Maternal Probiotic Intervention in Atopic Eczema Risk Reduction.

Probiotics have shown potential in reducing the occurrence of atopic eczema in high-risk infants. We aimed here to assess whether the preventive effect of maternal probiotic administration stems from compositional changes in early gut microbiota. This study included 46 mother-infant pairs from an original randomized controlled trial assessing the impact of maternal probiotic intervention with either the combinations of Lacticaseibacillus rhamnosus LPR and Bifidobacterium longum BL999, or Lacticaseibacillus paracasei ST11 and Bifidobacterium longum BL999, or placebo beginning 2 months before expected delivery and ending 2 months after birth. All children were vaginally delivered, full term and breastfed. During the 2-year follow-up period, the children were clinically evaluated by physicians for atopic eczema, and their gut microbiota was profiled at 1 and 6 months of age by 16S rRNA gene sequencing using an Illumina sequencing platform. Altogether, 19 of 46 children developed atopic eczema by the age of 2 years. At 1 and 6 months of age, gut microbial diversity was similar between children who developed atopic eczema and their healthy controls, but at the age of 6 months, children who developed atopic eczema manifested with significantly higher relative abundance of Clostridia. Probiotic intervention did not significantly influence microbial diversity, and the effects on microbial composition were not consistent with the changes associated with the development of atopic eczema. The reduction of the risk of atopic eczema achieved by perinatal maternal probiotic intervention does not seem to require substantial gut microbiota modulation.

A novel Bacillus aerolatus CX253 attenuates inflammation induced by Streptococcus pneumoniae in childhood and pregnant rats by regulating gut microbiome

Streptococcus pneumoniae (Spn) is the predominant pathogen responsible for community-acquired pneumonia (CAP) in children under five years old, and it can induce over 17% of pregnant women. However, no more effective measures exist to prevent infection induced by Spn in these two special populations. The beneficial microbes can antagonize Spn and provide new targets for preventing pneumococcal infections. This study used 16S rRNA gene sequencing and targeted metabolomics to evaluate the role of the Bacillus aerolatus CX253 (CX253) in alleviating Spn infection. Additionally, the colonization of CX253 was observed in nose, trachea, and lung by using confocal laser scanning microscopy and fluorescent labeling techniques. Compared with the model group, the expression level of interleukin-1β was dropped 1.81-fold and 2.22-fold, and interleukin-6 was decreased 2.39-fold and 1.84-fold. The express of tumor necrosis factor-α was down 2.30-fold and 3.84-fold in prevention group of childhood and pregnant rats, respectively. The 16S rRNA sequencing results showed that CX253 administration alone significantly increased the abundance of Lactobacillus, Limosilactobacillus, and Prevotella in the gut of childhood and pregnant rats. Furthermore, the CX253 increased propionate in the gut of childhood rats and increased propionate and butyrate in the gut of pregnant rats to inhibit pulmonary inflammation. In summary, CX253 attenuated Spn-induced inflammation by regulating the gut microbiota and SCFAs. The research provides valuable information for the prevention of pneumonia.Graphical

Fecal bacterial communities of the platypus (Ornithorhynchus anatinus) reflect captivity status-Implications for conservation and management.

The duck-billed platypus (Ornithorhynchus anatinus) is currently listed as near-threatened. A key part of the conservation strategy for this species is its captive maintenance; however, captive animals often have dysbiotic gut bacterial microbiomes. Here, for the first time, we characterize the gut microbiome of wild platypus via fecal samples using high-throughput sequencing of the bacterial 16S rRNA gene and identify microbial biomarkers of captivity in this species. At the phylum level, Firmicutes (50.4%) predominated among all platypuses, followed by Proteobacteria (28.7%), Fusobacteria (13.4%), and Bacteroidota (6.9%), with 21 "core" bacteria identified. Captive individuals did not differ in their microbial α-diversity compared to wild platypus but had significantly different community composition (β-diversity) and exhibited higher abundances of Enterococcus, which are potential pathogenic bacteria. Four taxa were identified as biomarkers of wild platypus, including Rickettsiella, Epulopiscium, Clostridium, and Cetobacterium. This contrast in gut microbiome composition between wild and captive platypus is an essential insight for guiding conservation management, as the rewilding of captive animal microbiomes is a new and emerging tool to improve captive animal health, maximize captive breeding efforts, and give reintroduced or translocated animals the best chance of survival.

Changes in microbial community structure of bio-fouled polyolefins over a year-long seawater incubation in Hawai'i.

Plastic waste, especially positively buoyant polymers known as polyolefins, are a major component of floating debris in the marine environment. While plastic colonisation by marine microbes is well documented from environmental samples, the succession of marine microbial community structure over longer time scales (> > 1 month) and across different types and shapes of plastic debris is less certain. We analysed 16S rRNA and 18S rRNA amplicon gene sequences from biofilms on polyolefin debris floating in a flow-through seawater tank in Hawai'i to assess differences in microbial succession across the plastic types of polypropylene (PP) and both high-density polyethylene (HDPE) and low-density polyethylene (LDPE) made of different plastic shapes (rod, film and cube) under the same environmental conditions for 1 year. Regardless of type or shape, all plastic debris were dominated by the eukaryotic diatom Nitzschia, and only plastic type was significantly important for bacterial community structure over time (p = 0.005). PE plastics had higher differential abundance when compared to PP for 20 bacterial and eight eukaryotic taxa, including the known plastic degrading bacterial taxon Hyphomonas (p = 0.01). Results from our study provide empirical evidence that plastic type may be more important for bacterial than eukaryotic microbial community succession on polyolefin pollution under similar conditions.

Microbial life-history strategies and particulate organic carbon mediate formation of microbial necromass carbon and stabilization in response to biochar addition

Microbial necromass carbon (MNC) contributes significantly to the formation of soil organic carbon (SOC). However, the microbial carbon sequestration effect of biochar is often underestimated and influenced by nutrient availability. The mechanisms associated with the formation and stabilization of MNC remain unclear, especially under the combined application of biochar and nitrogen (N) fertilizer. Thus, in a long-term field experiment (11 years) based on biochar application, we utilized bacterial 16S rRNA gene sequencing, fungal ITS amplicon sequencing, metagenomics, and microbial biomarkers to examine the interactions between MNC accumulation and microbial metabolic strategies under combined treatment with biochar and N fertilizer. We aimed to identify the critical microbial modules and species involved, and to analyze the sites where MNC was immobilized from various components. Biochar application increased the MNC content by 13.9 %. Among the MNC components, fungal necromass contributed more to MNC, but bacteria were more readily enriched after biochar application. The microbial life-history strategies that affected MNC formation under the application of various amounts biochar were linked to the N application level. Under N added at 226.5 kg ha−1, communities such as Actinobacteria and Bacteroidetes with high-growth yield strategies were prevalent and contributed to MNC production. By contrast, under N added at 113.25 kg ha−1 with high biochar application, Proteobacteria with strong resource acquisition strategies were dominant and MNC accumulation was lower. The mineral-associated organic carbon pool was rapidly saturated with the addition of biochar, so the contribution of fungal necromass carbon may have been reduced by reutilization, thereby resulting in the more rapid preservation of bacterial necromass carbon in the particulate organic carbon pool. Overall, our findings indicate that microbial life history traits are crucial for linking microbial metabolic processes to the accumulation and stabilization of MNC, thereby highlighting the their importance for SOC accumulation in farmland soils, and the need to tailor appropriate biochar and N fertilizer application strategies for agricultural soils.

Firmicutes and Bacteroidetes as the dominant microorganisms for ammonium nitrogen wastewater treatment with a low C/N ratio in BCOR

Improving nitrogen removal is a significant concern in the biological treatment of ammonium nitrogen (NH4+-N) wastewater with low chemical oxygen demand (COD)/NH4+-N (C/N) ratio, and microorganisms are the critical factor affecting nitrogen removal. In this study, a laboratory-scale biological contact oxidation reactor (BCOR) system was successfully started up (day 1 to day 47) and stabilized (day 48 to day 320). A 16S rRNA gene sequencing analysis showed that the phyla Firmicutes and Bacteroidetes were first observed as the dominant microorganisms in the BCOR for the ammonium nitrogen wastewater treatment with a low C/N ratio. The genera Bacteroides (phylum Bacteroidetes), Porphyromonas (phylum Bacteroidetes), Dialister (phylum Firmicutes), and Anaerococcus (phylum Firmicutes) also became the main microorganisms in this system for the first time. These microbial communities enabled the system to achieve an average ammonium nitrogen removal efficiency and total nitrogen removal efficiency of 95.8 % and 88.1 %, respectively, during the operational period. It indicated that these dominant microorganisms in the BCOR system played an essential role in improving the performance of biological nitrogen removal. This conclusion will play a critical role in promoting the microbial mechanism research and technology engineering application of the BCOR system for treating ammonium nitrogen wastewater with a low C/N ratio.

Isolation and identification of marine microalgae from Egyptian coasts as potential source of biodiesel: morphology and sequence-based screening

ABSTRACT Microalgae are a highly effective and renewable source of biodiesel that can be used as a substitute for petro-diesel in the global fuel market. In the present study, 14 water samples were collected from a variety of locations along the coastal areas of the Red Sea and the Mediterranean Sea in Egypt. These water samples, which contained microalgae, were subjected to enrichment process and standard procedures to obtain pure cultures. Based on morphological features, 27 microalgae isolates representing 12 different species were identified, with Chlorella species being the most dominant. Based on 18s rRNA gene sequencing, nine new native microalgae strains were identified, comprising four strains belonging to Chlorella species, two strains to Chlamydomonas, and one strain each of Phormidium, Nostoc, and Microcytosis species that could be appropriate for producing biodiesel. This information could be used to improve the knowledge on the composition of planktonic microalgal communities of Egypt and the target native species for biodiesel production.

Microbial Biodiversity of Cryoconites in Palandöken Mountain and Culturing Cold-Adapted Enzyme Producers

Palandöken Mountain is among the highest and coldest ecosystems of Türkiye, and knowledge on its microbial diversity has not been adequately characterized. The aim of the present study is to expand the current understanding of microbial diversity in Palandöken Mountain. Sampling studies were carried out at in winter an altitude of 2400–2900 m. A next-generation sequencing (NGS) based culture-independent approach was employed for elucidating the community structure in the 8 cryoconite samples using 16S and 23S rRNA gene sequencing. In addition, biotechnologically important cold-adapted enzyme producers were isolated and identified by employing conventional culture-dependent studies. High-throughput sequencing analysis revealed the presence of 36 bacterial and 2 fungal phyla. The bacterial communities of 8 samples were dominated by Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes and Acidobacteria. The fungal communities were dominated by Ascomycota and Basidiomycota. 2900 different taxonomic group for bacterial diversity and 51 for fungal diversity were reported in the present study. Furthermore, 25 cold-adapted enzyme-producers were isolated and identified in the culture-dependent studies. Each selected isolate was capable of producing at least one of the enzymes amylase, protease, lipase, cellulase and xylanase isolates were assigned to Aspergillus, Bacillus, Cladosporium, Dioszegia, Flavobacterium, Fusarium, Holtermanniella, Naganishia, Polaromonas, Protomyces, Pseudomonas Rhodosporidiobolus, Vishniacozyma and Yarrowia genera. Consequently, this is the first geomicrobiological investigation that describes bacterial and fungal diversity of cryoconites from Palandöken Mountain using an NGS-based culture-independent approach. Additionally, cultured cold-adapted enzyme producer isolates of the present study have a valuable potential for the development of new biotechnological tools for various industrial applications.

Atacama desert actinomycetes: taxonomic analysis, drought tolerance and plant growth promoting potential.

This study was designed to recover representative culturable actinomycetes from the Atacama Desert, and to detect their ability to promote plant growth under drought conditions. Environmental samples were taken from three Atacama Desert habitats, namely, from the Aguas Calientes, Lomas Bayas and Yungay core regions. With one exception higher actinomycete counts were obtained when isolation media were inoculated with mineral particles than with corresponding aliquots of serial dilution. Comparative 16S rRNA gene sequencing showed that representative isolates belonged to thirteen genera including putative novel Blastococcus, Kocuria, Micromonospora, Pseudonocardia, Rhodococcus and Streptomyces species. Representative isolates produced indole-3-acetic acid, siderophore and solubilized phosphate as well as displaying an ability to grow under drought conditions. In conclusion, the current findings open up exciting prospects for the promising potential of actinomycetes from the Atacama Desert to be used as bioinoculants to promote plant growth in arid and semi-arid biomes.

Chengkuizengella axinellae sp. nov., a symbiotic bacterium isolated from a marine sponge of the genus Axinella.

A Gram-stain-positive, strictly aerobic, creamy-white colored, endospore-forming and non-motile rods strain, designated as strain 2205SS18-9T, was isolated from a marine sponge, Axinella sp. collected from Seopseom Island, Republic of Korea. Optimal growth of strain 2205SS18-9T was observed at 25-30°C, pH 6.5-7.0, and in the presence of 3.0% (w/v) NaCl. Cells were oxidase-positive and catalase-negative. Negative for nitrate reduction and indole production. Phylogenetic analyses based on the 16S rRNA gene and whole-genome sequences revealed that strain 2205SS18-9T formed a distinct phyletic lineage in the genus Chengkuizengella, and it was most closely related to Chengkuizengella marina YPA3-1-1T and Chengkuizengella sediminis J15A17T with 97.1 and 96.6% 16S rRNA gene sequence similarities, respectively. The average nucleotide identity and digital DNA-DNA hybridization values between strain 2205SS18-9T and Chengkuizengella marina YPA3-1-1T were 79.0 and 21.6%, respectively. The genomic DNA G + C content was 34.1%. The genome harbors a number of host-adhesion and transporter genes, suggested that strain 2205SS18-9T may interact with its sponge host as a symbiont. Menaquinone-7 was the sole isoprenoid quinone and antieiso-C15:0 (28.5%), iso-C16:0 (25.8%), C16:1 ω7c alcohol (15.0%), and iso-C15:0 (11.2%) were detected as the major fatty acids. Polar lipids included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two unidentified aminophospholipids, and an unidentified lipid. The cell-wall peptidoglycan contained lysine, alanine, glutamate, and aspartate. Based on these analyses, strain 2205SS18-9T represents a novel species of the genus Chengkuizengella, for which the name Chengkuizengella axinellae sp. nov. is proposed. The type strain is 2205SS18-9T (= KACC 23238T = LMG 33063T).