Isolation and preliminary characterization of a respiratory nitrate reductase from hydrocarbon-degrading bacterium Gordonia alkanivorans S7

Characterization of Oral Bacterial Composition of Adult Smokeless Tobacco Users from Healthy Indians Using 16S rDNA Analysis

The present investigation is aiming to report the oral bacterial composition of smokeless tobacco (SLT) users and to determine the influence of SLT products on the healthy Indian population. With the aid of the V3 hypervariable region of the 16S rRNA gene, a total of 8,080,889 high-quality reads were clustered into 15 phyla and 180 genera in the oral cavity of the SLT users. Comparative analysis revealed a more diverse microbiome where two phyla and sixteen genera were significantly different among the SLT users as compared to the control group (p-value < 0.05). The prevalence of Fusobacteria-, Porphyromonas-, Desulfobulbus-, Enterococcus-, and Parvimonas-like genera among SLT users indicates altered bacterial communities among SLT users. Besides, the depletion of health-compatible bacteria such as Lactobacillus and Haemophilus also suggests poor oral health. Here, the majority of the altered genera belong to Gram-negative anaerobes that have been reported for assisting biofilm formation that leads in the progression of several oral diseases. The PICRUSt analysis further supports the hypothesis where a significant increase in the count of the genes involved in the metabolism of nitrogen, amino acids, and nicotinate/nicotinamide was observed among tobacco chewers. Moreover, this study has a high significance in Indian prospects where the SLT consumers are prevalent but we are deficient in information on their oral microbiome.

Gordonia mangrovi sp. nov., a novel actinobacterium isolated from mangrove soil in Hainan

A novel actinobacterium, designated strain HNM0687^T, was isolated from mangrove soil samples collected from Hainan Province, PR China and its polyphasic taxonomy was studied. Based on the results of 16S rRNA gene sequence analysis, strain HNM0687^T was closely related to Gordonia bronchialis NBRC 16047^T (98.7 %), Gordonia rhizosphera NBRC 16068^T (98.2 %), Gordonia oryzae RS15-1S^T (97.9 %), Gordonia polyisoprenivorans NBRC 16320^T (97.7 %) and Gordonia sediminis AMA 120^T (97.7 %). Genome-based comparisons revealed a clear distinction in average nucleotide identity values between strain HNM0687^T and its closely related strains (74.4-78.3 %). Strain HNM0687^T contained meso-diaminopimelic acid, arabinose and galactose in whole-cell hydrolysates. Mycolic acid was present. The menaquinones of strain HNM0687^T were MK-9(H₂) and MK-7(H₂). The phospholipids of the isolate were composed of diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol. The major fatty acids were C_16 : 0, C_16 : 1  ω7c/C_16 : 1  ω6c, C_18 : 010-methyl (TBSA), C_18 : 0 and C_18 : 1  ω9c. Based on its genotypic, chemotaxonomic and phenotypic characteristics, it is concluded that strain HNM0687^T represents a novel species of the genus Gordonia for which the name Gordonia mangrovi sp. nov. is proposed. The type strain is HNM0687^T (=CCTCC AA 2019074 ^T=KCTC 49383 ^T).

NAP enzyme recruitment in simultaneous bioremediation and nanoparticles synthesis

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This study employed the immobilized strain MMT and its NAP enzyme in concurrent denitrification and NPs synthesis.

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The properties of crude NAP enzyme were assessed at different ranges of pH and temperatures and also its stability at 4 °C and 30 °C was studied.

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The effect of several types of additives were evaluated at concentration rang (1 mM, 2.5 mM, 5 mM and 10 mM).

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Concurrently, the immobilized MMT cells completely removed NO₃⁻ upon 8th day with AgNPs synthesis ranging from 23.26 to 58.14.

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Immobilized NAP exhibited lower efficiency with 28.6% of NO₃ elimination and large aggregated AgNPs ranging from 94.44 nm to 172.22 nm.

The periplasmic nitrate reductase enzyme (NAP) has become attractive catalyst, whose exploitation has emerged as one of the indispensable strategies toward environmentally benign applications. To achieve them efficiently and overcome the sensitivity of NAP in harsh environmental circumstances, the immobilization for denitrifying bacteria and NAP enzyme for simultaneous bioremediation and bionanoparticles synthesis was studied. NAP catalyzed NO₃⁻ reduction at V_max of 0.811 μM/min and K_m of 14.02 mM. Concurrently, the immobilized MMT cells completely removed NO₃- upon 192 h with AgNPs synthesis ranging from 23.26 to 58.14 nm as indicated by SEM. Wherase, immobilized NAP exhibited lower efficiency with 28.6% of NO₃⁻ elimination within 288 h and large aggregated AgNPs ranging from 94.44 nm to 172.22 nm. To the best of author knowledge, the immobilization for denitrifying bacteria and NAP enzyme for simultaneous bioremediation and bionanoparticles synthesis was not studied before.

Population Dynamics of Bulking and Foaming Bacteria in a Full-scale Wastewater Treatment Plant over Five Years

Bulking and foaming are two notorious problems in activated sludge wastewater treatment plants (WWTPs), which are mainly associated with the excessive growth of bulking and foaming bacteria (BFB). However, studies on affecting factors of BFB in full-scale WWTPs are still limited. In this study, data sets of high-throughput sequencing (HTS) of 16S V3–V4 amplicons of 58 monthly activated sludge samples from a municipal WWTP was re-analyzed to investigate the BFB dynamics and further to study the determinative factors. The population of BFB occupied 0.6~36% (averagely 8.5% ± 7.3%) of the total bacteria and showed seasonal variations with higher abundance in winter-spring than summer-autumn. Pair-wise correlation analysis and canonical correlation analysis (CCA) showed that Gordonia sp. was positively correlated with NO₂-N and negatively correlated with NO₃-N, and Nostocodia limicola II Tetraspharea sp. was negatively correlated with temperature and positively correlated with NH₃-N in activated sludge. Bacteria species correlated with BFB could be clustered into two negatively related modules. Moreover, with intensive time series sampling, the dominant BFB could be accurately modeled with environmental interaction network, i.e. environmental parameters and biotic interactions between BFB and related bacteria, indicating that abiotic and biotic factors were both crucial to the dynamics of BFB.

The strengths and weaknesses of Gordonia: a review of an emerging genus with increasing biotechnological potential

This review about the genus Gordonia provides a current overview of recent research on a young genus that was introduced in the year 1997 ( Stackebrandt et al., 1997 ). This emerging genus has attracted increasing environmental, industrial, biotechnological and medical interest during the last few years, in particular due to the capabilities of its members to degrade, transform, and synthesize organic compounds as well as to the pathogenic effects that have been described in many case studies. The number of publications about Gordonia has increased significantly after the year 2004 (the year of the first Gordonia review published by Arenskötter et al.) describing 13 new validly published species (type strains), many newly described physiological and metabolic capabilities, new patent applications and many new case reports of bacterial infections. Members of the genus Gordonia are widely distributed in nature and it is therefore important to unravel the species richness and metabolic potential of gordoniae in future studies to demonstrate their environmental impact especially on the degradation of persistent organic compounds and their ecological participation in the carbon cycle of organic material in soil and water. This review summarizes mainly the current state of importance and potential of the members of this genus for the environmental and biotechnological industry ("the strengthsâ) and briefly its pathogenic impact to humans ("the weaknessesâ).