Vol 1, No 2 (2016)

Volume 1 Issue 2

Table of Contents

RESEARCH ARTICLES

by Katarzyna Pietrzak, Anna Otlewska, Michał Puchalski, Beata Gutarowska, Patricia Guiamet
148 Views, 123 PDF Downloads
The aims of this work were to: (i) microscopically analyse the pre- and post-Columbian archaeological textiles using Scanning Electron Microscopy with Energy Dispersive X-Ray Analysis (SEM-EDX); (ii) microbiologically analyse the archaeological textiles (from the Southern Andean Area, La Plata Museum); (iii) determine the ability of Pseudomonas sp. isolates from archaeological textiles to biofilm formation by SEM; (iv) assess the anti-biofilm properties of AgNPs protecting cotton against Pseudomonas sp. Results showed the presence of bacteria with proteolytic and lipolytic activities on archaeological textiles, including Clostridium sp. and Pseudomonas aeruginosa. Two nucleotide sequences of 16S ribosomal RNA gene of P. aeruginosa strains were deposited in GeneBank NCBI database with accession numbers: KP842564 (strain 1) and KP842565 (strain 2). Those strains exhibited different morphological and growth characteristics: strain 1 with ability to form biofilms on archaeological textiles was rod-shaped, produced bluish-green pigment, and smaller than strain 2; and strain 2 was pleomorphic and produced brown pigment. The use of silver nanoparticles (90 ppm, φ 10–80 nm) allowed to protecting textiles against P. aeruginosa growth by 63%–97%, depending on the strain and exposition time.
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RESEARCH ARTICLES

by Hong Liang, Xue Li, Shanshan Wang, Dawen Gao
160 Views, 102 PDF Downloads
A sequencing batch reactor (SBR) was used to study the effect of carbon source (C6H12O6 and CH3COONa) and C/N ratio (C/N=4:1 and C/N=7:1) on the production of nitrous oxide (N2O) in the process of simultaneous nitrifica-tion and denitrification via nitrite (short-cut SND) by aerobic granular sludge and the removal efficiency of nitrogen under low dissolved oxygen (DO). The results showed that short-cut SND occurred in this system, and the removal ef-ficiency of total nitrogen (TN) at C6H12O6 and CH3COONa were 28.93 % and 41.19 %, respectively. However, the production of N2O significantly increased when CH3COONa was used as a carbon source. In addition, the rate of N2O release when CH3COONa was a carbon source was 8.34 times the rate when C6H12O6 was the carbon source. With the increase of C/N, removal rate of TN and the efficiency of the short-cut SND were increased. The removal efficiency of TN at C/N=7:1 was 90.33%, which was 2.19 times at C/N=4:1. The percentage of short-cut SND at C/N=4:1 and C/N=7:1 were 87.47% and 95.97%, respectively. The release rate of N2O from the original 1.14 mg/(g • min) decreased to 0.10 mg/(g • min) after increased the C/N from 4:1 to 7:1.
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RESEARCH ARTICLES

by Hong Liang, Shutong Liu, Xue Li, Xueying Sun, Dawen Gao
200 Views, 112 PDF Downloads

An external circulation Sequencing Batch Reactor (ecSBR) was used to study the efficiency of nitrogen removal by autotrophic microbe. With gradually reducing the dissolved oxygen (DO) concentration from 1.2 mg/L to 0.04 mg/L, the single-stage autotrophic biological nitrogen removal (sABNR) process could be operated stably. After removing the aeration, the process could still stay sABNR stably, and the concentration of NH4+-N was 0.9 mg/L in effluent, the rate of nitrate (produced)/NH4+-N (removed) was in the range of 0.12–0.40. The results showed that the concentration of NH4+-N in effluent was 0.8, 0.8 and 9.9 mg/L with the hydraulic retention time (HRT) at 8 h, 6 h and 4 h respectively, the removal efficiency of ammonia were 98.2%, 98.1% and 73.6% respectively. The rate of nitrate (produced)/NH4+-N (consumed) was 0.05 at HRT 6 h, and the nitrogen loading rate (NLR) and nitrogen removal rate (NRR) were 169.7 and 129.7 g/m3/d, the removal efficiency of total nitrogen (TN) was 77.5%. In conclusion the optimal HRT was 6 h instead of 8 h or 4 h enough for ammonia removal without causing energy wastage.

 

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RESEARCH ARTICLES

by Jin-Feng Liu, Serge Maurice Mbadinga, Wen-Ji Ke, Ji-Dong Gu, Bo-Zhong Mu
203 Views, 132 PDF Downloads

Hydrogen-producing microorganisms are believed to play an important role in energy metabolism of micro-organisms in anaerobic environments and hence are one of the crucial factors for influencing the activity and develop-ment of these microorganisms. Consequently, they provide the biological foundation for the biotechnology such as MEOR (Microbial Enhanced Oil Recovery) and microbial fixation of CO2 and conversion of it into CH4 and etc. How-ever, knowledge on the community of hydrogen-producing microorganisms and their potential in subsurface formations are still limited. In this study, hydrogen-producing microorganisms in the production water from an oilfield as well as enrichment cultures were analyzed with clone library analysis of [FeFe]-hydrogenase encoding genes. The results show that [FeFe]-hydrogenase genes in production water are diverse and related to Bacteroidetes, Firmicutes, Spirochaetes and uncultured. Anaerobic incubations established within the oil reservoir production water and generating 202 mmol H2/mol glucose during 7-day incubation at 55°C indicate a high frequency of members of the Firmicutes. This study implies that hydrogen-producing microorganisms in oil reservoir may play a positive role in promoting the in situ bio-process via hydrogen production once common nutrients are available. These data are helpful for evaluating, developing, and utilizing hydrogen-producing microorganisms in oil reservoirs for biological fixation and conversion of CO2 into CH4 as well as MEOR.

 

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RESEARCH ARTICLES

by Jin-Feng Liu, Wei-Lin Wu, Feng Yao, Biao Wang, Bing-Liang Zhang, Serge Maurice Mbadinga, Ji-Dong Gu, Bo-Zhong Mu
238 Views, 146 PDF Downloads
A thermophilic spore-forming facultative anaerobic bacterium, designated as Njiang2, was isolated from the production water of a high temperature oil reservoir (87°C). The physiological, biochemical and 16S rRNA gene based phylogenetic analysis indicated that Njiang2 belonged to the genus Anoxybacillus. Njiang2 could significantly inhibit H2S production when co-cultured with Desulfotomaculum sp under laboratory conditions, which implied its great potential in mitigation of brine souring in the oil reservoir and in control of biocorrosion caused by sulfate-reducing bacteria. As far as we know, this might be the first report of Anoxybacillus sp. isolated from high temperature oilfield
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RESEARCH ARTICLES

by Nova Maulani, Qian Li, Wolfgang Sand, Mario Vera, Ruiyong Zhang
197 Views, 110 PDF Downloads

Bioleaching has been applied as a successful technique for metal recovery from various mineral sources like low-grade ores, waste materials and tailings. Mixed cultures of bioleaching microorganisms have a high performance in mineral dissolution. Thus far, microbial interactions in bioleaching communities are poorly understood. In this paper, the acidophilic archaeon Ferroplasma acidiphilum and the bacteria Leptospirillum ferriphilum and Sulfobacillus thermosulfidooxidans were chosen to study their interactions during pyrite leaching. The initial attachment to pyrite and pyrite leaching efficiency of pure and mixed populations were investigated. The data indicate: (i) attachment and bioleaching efficiency of L. ferriphilum was reduced in the presence of F. acidiphilum. However, the combination of F. acidiphilum and S. thermosulfidooxidans showed increased leaching, although the initial attachment rate was reduced, when compared to pure cultures. Thus, synergistic or antagonistic interactions may exist between F. acidiphilum and S. thermosulfidooxidans or F. acidiphilum and L. ferriphilum, respectively; (ii) pre-established biofilms of L. ferriphilum inhibited initial attachment to pyrite by cells of F. acidiphilum and did not promote pyrite leaching by F. acidiphilum. In contrast, inactivated biofilm cells of S. thermosulfidooxidans enhanced pyrite bioleaching by F. acidiphilum; (iii) adhesion forces of cells to an AFM tip (Si3N4) seemed to be not correlated to attachment and bioleaching capacity; and (iv) lectins were applied to show and distinguish single species in mixed biofilm populations. Physical contact between cells of S. thermosulfidooxidans and F. acidiphilum was visible.

 

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RESEARCH ARTICLES

by Xiaoying Dong, Xiao Zhuo, Chang Liu, Jie Wei, Gang Zhang, Rutan Pan, Yongfeng Li
196 Views, 143 PDF Downloads
In order to improve the decay resistance of wood, we propose a novel method by in-situ hybridization of reactive monomers and nano-SiO2 within wood porous structure to modify wood structure and chemical components. Glycidyl methacrylate (GMA), and polyethylene glycol-200 dimethacrylate (PEGDMA) were first mixed and then penetrated into poplar wood cell lumen by vacuum/pressure treatments, followed by in-situ hybridization under an initiation condition. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and transmission electron microscopy (TEM) observations described that the polymer-inorganic hybrid nanocomposite filled up cavities and tightly contacted the wood cell wall. Nano-SiO2 particles were uniformly dispersed into the formed polymer within wood pores. Fourier transform infrared spectroscopy (FTIR) analysis suggested that the nano-SiO2 probably chemical bonded to the polymer during the monomer polymerization. The derived wood-based polymer-inorganic hybrid nanocomposite exhibited remarkably improvement in decay resistance over the untreated wood as controls. Such treatment could potentially widen the wood applications with outstanding decay resistance.
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COMMENTARY

by Ji-Dong Gu
128 Views, 76 PDF Downloads
Bacterial growth is a very important piece of information in a wide range of investigation and, in most of the time the data are simply shown directly without any further processing. In a single factor investigation without comparative information to be extracted, this simple approach can be used together with other data to form a comprehensive set of results. When comparison is involved, such direct showing of bacterial growth curves without processing cannot warrant a meaningful comparison thoroughly and further processing of data is necessary. In addition, there is little, if any, quantitative data for the comparison from the display of growth curves and description of a number of curves is not a simple task, especially in a meaningful way for assimilation of the data to readers. With this in mind, I would like to remind of those who plan to show such data as growth curves for their potential publication to carry this further to generate comparative results for a much meaningful interpretation by modeling and calculation from the raw growth data over time of incubation. By calculating with existing equations, the lag phase, growth rate and the biomass can be derived from a series of growth curves for a more effective and meaningful analysis. This approach is not new, but remembrance of such available tool is more important so that research data are shown professionally and also scientifically for meaning presentation and effective assimilation.
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