Effects of oxygen exposure on relative nucleic acid content and membrane integrity in the human gut microbiota

While the diversity of the human gut microbiota is becoming increasingly well characterized, bacterial physiology is still a critical missing link in understanding how the gut microbiota may be implicated in disease. The current best practice for studying bacterial physiology involves the immediate storage of fecal samples in an anaerobic chamber. This reliance on immediate access to anaerobic chambers greatly limits the scope of sample populations that can be studied. Here, we assess the effects of short-term oxygen exposure on gut bacterial physiology and diversity. We use relative nucleic acid content and membrane integrity as markers of bacterial physiology, and 16S rRNA gene amplicon sequencing to measure bacterial diversity. Samples were stored for up to 6 h in either ambient conditions or in anoxic environments created with gas packs or in an anaerobic chamber. Our data indicate that AnaeroGen sachets preserve bacterial membrane integrity and nucleic acid content over the course of 6 h similar to storage in an anaerobic chamber. Short-term oxygen exposure increases bacterial membrane permeability, without exceeding inter-individual differences. As oxygen exposure remains an important experimental consideration for bacterial metabolism, our data suggest that AnaeroGen sachets are a valid alternative limiting loss of membrane integrity for short-term storage of samples from harder-to-access populations.

High Electric Production by Membraneless Microbial Fuel Cell with Up Flow Operation Using Acetate Wastewater

Microbial fuel cell (MFC) is a new proposed technology reported to generate renewable energy while simultaneously treating wastewater. Membraneless microbial fuel cell (ML-MFC) system was developed to eliminate the requirement of membrane which is expensive and prone to clogging while enhancing electricity generation and wastewater treatment efficiency. For this purpose, a reactor was designed in two chambers and connected via three pipes (1 cm in diameter) to enhance fluid diffusion. Influent flowrate was maintained by adjusting peristaltic pump at the base of anaerobic chamber. Carbon cloth (235 cm2) was used as anode and paired with gas diffusion layer (GDL) carbon-Pt as cathode. Anaerobic sludge was filtered and used as starter feed for the anaerobic chamber. The experiment was carried out by feeding synthetic wastewater to anaerobic chamber; while current response and potential were recorded. Performance of reactor was evaluated in terms of chemical oxygen demand (COD). Electroactive microbe was inoculated from anaerobic sludge and showed current response (0.55-0.65 mA) at 0,35 V, range of diameter 1.5-2 µm. The result of microscopics can showed three different species. The microbial performance was increased by adding ferric oxide 1 mM addition as acceptor electron. The reactor was able to generate current, voltage, and electricity power of 0.36 mA, 110 mV, and 40 mWatt (1.5 Watt/m2), respectively, while reaching COD removal and maximum coulomb efficiency (EC) of 16% and 10.18%, respectively.

Performance of modified twin pit toilet in Mulbagal town, Karnataka, India

Transformation of ammonium to nitrate upon sewage discharge to sub-surface environment exposes about 65 million households in rural and urban India to risks of drinking nitrate contaminated groundwater. Building on earlier research, a twin pit is modified in Mulbagal town, Karnataka, to remove nitrate in pit toilet sewage and is functional for nearly one year. The first pit serves as an anaerobic chamber, while the second pit facilitates aerobic reactions in the upper half and is equipped with a bio-barrier in its lower half. Quality of treated sewage is monitored by soil water samplers installed adjacent to the pit. After anaerobic digestion in pit 1, sewage flows into the aerobic chamber (upper half of pit 2), where COD/N ratio of 1.49 to 1.73 facilitates aerobic conversion of ammonium to nitrite and nitrate ions. Annamox reactions in a bio-barrier chamber (lower half of pit 2) reduce ammonium and nitrite concentrations, while denitrification reactions in the bio-barrier remove nitrite and nitrate from pit toilet sewage. Besides nitrate, the modified twin pit reduces COD (chemical oxygen demand), ammonium, and thermotolerant coliform levels in the discharged sewage.

Complete Genome Sequence of Thermoanaerobacterium sp. Strain RBIITD, a Butyrate- and Butanol-Producing Thermophile

ABSTRACT Thermoanaerobacterium sp. strain RBIITD was isolated from contaminated rich growth medium at 55°C in an anaerobic chamber. It primarily produces butyrate as a fermentation product from plant biomass-derived sugars. The whole-genome sequence of the strain is 3.4 Mbp, with 3,444 genes and 32.48% GC content.

Anaerobic crystallization for protein crystallography

Crystallization has been a bottleneck in protein crystallography. Major problems in protein crystallization are 1) to find crystallization conditions effectively at the initial crystallization screening and 2) to improve the reproducibility of protein crystallization. To overcome these problems, we have proposed some techniques such as the immediate observation method (1). Recently, we realized that films and precipitates of oxidized proteins hampered the crystal formation, leading to poor reproducibility of the crystallization. To avoid oxidation of proteins, we examined anaerobic crystallization in an anaerobic chamber. The anaerobic chamber (Anaerobic `HARD', Hirasawa) was designed to carry out controlled anaerobic experiments for electron-transfer proteins. We have so far established typical procedures for the anaerobic crystallization (2). On the basis of our earlier experiences, the anaerobic crystallization was tested for various proteins. We found obvious differences between aerobic and anaerobic crystallization in some cases; some proteins could crystallize only under anaerobic conditions. Furthermore, the anaerobic crystallization improved reproducibility of crystallization as expected. We will report some examples of the anaerobic crystallization.