Bacterial Oxidation Research Articles

Blocking Bacterial Naphthohydroquinone Oxidation and ADP-Ribosylation Improves Activity of Rifamycins against Mycobacterium abscessus.

ABSTRACTRifampicin is an effective drug for treating tuberculosis (TB) but is not used to treat Mycobacterium abscessus infections due to poor in vitro activity. While rifabutin, another rifamycin, has better anti-M. abscessus activity, its activity is far from the nanomolar potencies of rifamycins against Mycobacterium tuberculosis. Here, we asked (i) why is rifabutin more active against M. abscessus than rifampicin, and (ii) why is rifabutin’s anti-M. abscessus activity poorer than its anti-TB activity? Comparative analysis of naphthoquinone- versus naphthohydroquinone-containing rifamycins suggested that the improved activity of rifabutin over rifampicin is linked to its less readily oxidizable naphthoquinone core. Although rifabutin is resistant to bacterial oxidation, metabolite and genetic analyses showed that this rifamycin is metabolized by the ADP-ribosyltransferase ArrMab like rifampicin, preventing it from achieving the nanomolar activity that it displays against M. tuberculosis. Based on the identified dual mechanism of intrinsic rifamycin resistance, we hypothesized that rifamycins more potent than rifabutin should contain the molecule’s naphthoquinone core plus a modification that blocks ADP-ribosylation at its C-23. To test these predictions, we performed a blinded screen of a diverse collection of 189 rifamycins and identified two molecules more potent than rifabutin. As predicted, these compounds contained both a more oxidatively resistant naphthoquinone core and C-25 modifications that blocked ADP-ribosylation. Together, this work revealed dual bacterial metabolism as the mechanism of intrinsic resistance of M. abscessus to rifamycins and provides proof of concept for the repositioning of rifamycins for M. abscessus disease by developing derivatives that resist both bacterial oxidation and ADP-ribosylation.

34S enrichment as a signature of thiosulfate oxidation in the "Proteobacteria".

Kinetics of thiosulfate oxidation, product and intermediate formation, and 34S fractionation, were studied for the members of Alphaproteobacteria Paracoccus sp. SMMA5 and Mesorhizobium thiogangeticum SJTT, the Betaproteobacteria member Pusillimonas ginsengisoli SBO3, and the Acidithiobacillia member Thermithiobacillus sp. SMMA2, during chemolithoautotrophic growth in minimal salts media supplemented with 20mM thiosulfate. The two Alphaproteobacteria oxidized thiosulfate directly to sulfate, progressively enriching the end-product with 34S; Δ34Sthiosulfate-sulfate values recorded at the end of the two processes (when no thiosulfate was oxidized any further) were -2.9‰ and -3.5‰, respectively. Pusillimonas ginsengisoli SBO3 and Thermithiobacillus sp. SMMA2, on the other hand, oxidized thiosulfate to sulfate via tetrathionate intermediate formation, with progressive 34S enrichment in the end-product sulfate throughout the incubation period; Δ34Sthiosulfate-sulfate, at the end of the two processes (when no further oxidation took place), reached -3.5‰ and -3.8‰, respectively. Based on similar 34S fractionation patterns recorded previously during thiosulfate oxidation by strains of Paracoccus pantotrophus, Advenella kashmirensis and Hydrogenovibrio crunogenus, it was concluded that progressive reverse fractionation, enriching the end-product sulfate with 34S, could be a characteristic signature of bacterial thiosulfate oxidation.

Enhancing the retention of phosphorus through bacterial oxidation of iron or sulfide in the eutrophic sediments of Lake Taihu

Microbial activity can enhance the sequestration of phosphorus (P) in sediments, but little is known about the mechanisms behind it. In this study, sediment cores were sampled from the most eutrophic Meiliang Bay of Lake Taihu, and three treatments were set up in a laboratory incubation experiment, involving (a) the non-treated sediment cores, (b) inoculation, and (c) sterilization. The dissolved and labile iron (Fe) and P were obtained by high-resolution dialysis and the diffusive gradients in thin films (DGT) technique, respectively. AgI-based DGT was used for measuring the 2D distribution of labile sulfide. The bacterial community was investigated using a scanning electron microscope and 16S rRNA high throughput sequencing technique. The results showed that sterilization reduced the capacity of sediment to immobilize P, and that the critical sediment depth layer for microbial P sequestration was 0–10 mm. In addition, sterilization or inoculation significantly changes the structure of bacterial communities. Fe or S oxidation under micro-aerobic or anaerobic conditions played an important role in bacterial retention of P in the sediments. Nitrate-reducing coupling Fe(II)-oxidizing bacteria (Acidovorax) in the inoculated sediment and electrogenic sulfur-oxidizing bacteria (Candidatus Electronema) in the non-treated sediment were identified as the key bacterial genera responsible for the retention of P in sediments. This implies that bacterial communities could quickly establish the ability for negative feedback regulation by inoculation once the function and structure of indigenous sediment bacteria are seriously impaired, although this needs further validation in the field.

Intracellular Sulfur Inclusions: Source of Energy or Heater?

There are various groups of bacteria which receive energy from oxidation of inorganic sulfur compounds. Some of them produce elemental sulfur as an intermediate product and deposit it outside their cells. The group "sulfur bacteria" was described by their ability to produce intracellular sulfur inclusions. Traditionally, calculations of the released energy considered effect of the bacterial sulfide oxidation but never considered energy of the S-polymerization from monoatomic S to 8 atoms ring which is also essential (262.9kJ). Till present, no biochemical reactions are known which could use energy of this eight atoms ring formation process. Thus, it is proposed that the intracellular sulfur inclusions can provide a lasting heating content of the cells as an additional advantage for the sulfur bacteria.

A review of wastewater bacterial bio oxidation: mechanisms, reactions, and behaviors

The most overlooked biological process is the oxidation process, due to the poor technical understanding of bioremediation and the many unexplained biological mechanisms. As a matter of fact, wastewater companies favor the physical and chemical approaches over the biological means to ensure process performance. Biological oxidation provides environmentally friendly treatment with limited operational requirements. It has a tremendous ability to metabolize ammonia, H2S, phosphate, and ferrous iron under the right conditions. Bacterial communities attack these wastewater components through using oxygen as a strong electron acceptor, resulting in simplified forms of wastewater components (e.g., ammonia to nitrogen gas). This manuscript reviews in details the mechanisms of wastewater bacteria against various pollutants, with the possible reactions and behaviors. It also presents the benefits of utilizing wastewater microorganisms against different pollutants.

Small-Scale Geochemical Heterogeneities and Seasonal Variation of Iron and Sulfide in Salt Marshes Revealed by Two-Dimensional Sensors

Loss of tidal wetlands is a world-wide phenomenon. Many factors may contribute to such loss, but among them are geochemical stressors such as exposure of the marsh plants to elevated levels on hydrogen sulfide in the pore water of the marsh peat. Here we report the results of a study of the geochemistry of iron and sulfide at different seasons in unrestored (JoCo) and partially restored (Big Egg) salt marshes in Jamaica Bay, a highly urbanized estuary in New York City where the loss of salt marsh area has accelerated in recent years. The spatial and temporal 2-dimensional distribution patterns of dissolved Fe2+ and H2S in salt marshes were in situ mapped with high resolution planar sensors for the first time. The vertical profiles of Fe2+ and hydrogen sulfide, as well as related solutes and redox potentials in marsh were also evaluated by sampling the pore water at discrete depths. Sediment cores were collected at various seasons and the solid phase Fe, S, N, C, and chromium reducible sulfide in marsh peat at discrete depths were further investigated in order to study Fe and S cycles, and their relationship to the organic matter cycling at different seasons. Our results revealed that the redox sensitive elements Fe2+ and S2– showed significantly heterogeneous and complex three dimensional distribution patterns in salt marsh, over mm to cm scales, directly associated with the plant roots due to the oxygen leakage from roots and redox diagenetic reactions. We hypothesize that the oxic layers with low/undetected H2S and Fe2+ formed around roots help marsh plants to survive in the high levels of H2S by reducing sulfide absorption. The overall concentrations of Fe2+ and H2S and distribution patterns also seasonally varied with temperature change. H2S level in JoCo sampling site could change from <0.02 mM in spring to >5 mM in fall season, reflecting significantly seasonal variation in the rates of bacterial oxidation of organic matter at this marsh site. Solid phase Fe and S showed that very high fractions of the diagenetically reactive iron at JoCo and Big Egg were associated with pyrite that can persist for long periods in anoxic sediments. This implies that there is insufficient diagenetically reactive iron to buffer the pore water hydrogen sulfide through formation of iron sulfides at JoCo and Big Egg.

Study of biohydrometallurgical technology used to recover gold from ore at a gold-recovery plant

The article contains the results of the studies performed for the biochemical eхtraction modes for mineral raw materials using thionic bacteria Acidithiobacillusferrooxidans of a certain strain capable to oxidize sulfide minerals. A representative sample of mineral raw materials was taken, and its physical and chemical studies were performed. The optimal conditions to leach mineral raw materials with biochemical solvents based on various factors (temperature, S:W) were established. Modern physical and chemical methods of analysis were used during the study: X-ray fluorescence, X-ray phase, mineralogical, electron probe, chemical analyzes, IR methods to study the phase composition of ores and changes in the structure of minerals. The chemical composition of the ore sample quartered and crushed up to a size of -0.074 mm is as follows, wt. %: SiO2 - 60.11; Al2O3 6.2; Zn 0.016; Cu 0.10; Fe - 2.5; S 0.50; Au - 3.67 g/t and Ag - 3.2 g/t. This paper discusses various options for agitational leaching with acid pre-wash, bacterial dissection and oxidative decomposition of minerals using sodium hypochlorite. The results obtained showed that the most effective method to increase the gold recovery is to perform bacterial oxidation of ore using acidophilic bacteria At. Ferrooxidans preliminarily adapted to the material composition of the test sample, followed by treatment with sodium hypochlorite solution and cyanidation. Biohydrometallurgical ore processing provides high gold recovery (78.1%).

Wound Healing Composite Materials of Bacterial Cellulose and Zinc Oxide Nanoparticles with Immobilized Betulin Diphosphate.

A design of new nanocomposites of bacterial cellulose (BC) and betulin diphosphate (BDP) pre-impregnated into the surface of zinc oxide nanoparticles (ZnO NPs) for the production of wound dressings is proposed. The sizes of crystalline BC and ZnO NPs (5–25%) corresponded to 5–6 nm and 10–18 nm, respectively (powder X-ray diffractometry (PXRD), Fourier-infrared (FTIR), ultraviolet (UV), atomic absorption (AAS) and photoluminescence (PL) spectroscopies). The biological activity of the wound dressings “BC-ZnO NPs-BDP” was investigated in rats using a burn wound model. Morpho-histological studies have shown that more intensive healing was observed during treatment with hydrophilic nanocomposites than the oleophilic standard (ZnO NPs-BDP oleogel; p < 0.001). Treatment by both hydrophilic and lipophilic agents led to increases in antioxidant enzyme activity (superoxide dismutase (SOD), catalase) in erythrocytes and decreases in the malondialdehyde (MDA) concentration by 7, 10 and 21 days (p < 0.001). The microcirculation index was restored on the 3rd day after burn under treatment with BC-ZnO NPs-BDP wound dressings. The results of effective wound healing with BC-ZnO NPs-BDP nanocomposites can be explained by the synergistic effect of all nanocomposite components, which regulate oxygenation and microcirculation, reducing hypoxia and oxidative stress in a burn wound.

The Effect of Metal Ions on the Growth and Ferrous IronOxidation by Leptospirillum ferriphilum CC Isolated from Armenia Mine Sites

The aim of this study is to investigate the potential of newly isolated strain Leptospirillum (L.) ferriphilum CC for bioleaching of pyrite and chalcopyrite in pure or mixed culture with other iron- and/or sulfur-oxidizing bacteria. In this paper, kinetics of ferrous iron (Fe2+) oxidation by newly isolated strain Leptospirillum (L.) ferriphilum CC was studied. The effect of initial Fe2+ in the concentration range of 50–400 mM on bacterial growth and iron oxidation was studied. It was shown that microbial Fe2+ oxidation was competitively inhibited by Fe3+. The influence of copper, zinc, nickel and cobalt ions on the oxidation of Fe2+ by L. ferriphilum CC was also studied. Minimal inhibitory concentrations (MIC) for each metal ion were determined. The toxicity of the ions was found to be as follows: Co &gt; Zn &gt; Ni &gt; Cu. The comparison of iron oxidation kinetic parameters of L. ferriphilum CC with other strains of L. ferriphilum indicates the high potential of strain L. ferriphilum CC for biogenic regeneration of concentrated ferric iron (Fe3+) in bioleaching processes of ores and ore concentrates. Bioleaching tests indicated that the newly isolated L. ferriphilum CC can be a prospective strain for the bioleaching of sulfide minerals in pure culture or in association with other iron- and/or sulfur-oxidizing bacteria.

Bioleaching of Pyrrhotite with Bacterial Adaptation and Biological Oxidation for Iron Recovery

The microbially mediated recovery of valuable metals contained in mining waste presents an economical alternative to conventional hydrometallurgical processes. In order to investigate the effect of bacterial adaptation and biological oxidation on bioleaching, the microbially mediated bioleaching of a pyrrhotite sample from mine waste, with indigenous bacteria existing in acid mine drainage, was studied. The indigenous bacteria were sub-cultured repeatedly for iron adaptation, and Acidithiobacillus ferrooxidans was identified as the dominant member of the microbial consortium. The point of zero charge (PZC) of pyrrhotite sampled from mine waste was determined as 3.0. The performance of bioleaching by contact and non-contact biological oxidation was compared by conducting bioleaching under different initial pH (pHini) conditions (2.8 and 3.2). Negatively charged bacteria could be attached onto the pyrrhotite, which has a positive surface charge at lower pHini (2.8) than the PZC (3.0). Bacteria attachment and corrosion pits on the surface of the pyrrhotite residues were observed at pHini of 2.8. Under bacteria-adapted conditions, the leaching concentration of Fe (44.2 mg/L) at pHini of 2.8 was 2.1 times greater than that (21.3 mg/L) at pHini of 3.2. Under non-adapted bacteria conditions, the extent of Fe leaching was not significantly different between the pHini of 2.8 and 3.2. This could be attributed to the fact that the adapted bacteria could more easily attach onto the pyrrhotite surfaces at pHini 2.8, allowing contact biological oxidation during the bioleaching experiments. We demonstrate here that the bioleaching of pyrrhotite could increase Fe recovery through bacterial adaptation and contact biological oxidation.

Phanerozoic radiation of ammonia oxidizing bacteria

The modern nitrogen cycle consists of a web of microbially mediated redox transformations. Among the most crucial reactions in this cycle is the oxidation of ammonia to nitrite, an obligately aerobic process performed by a limited number of lineages of bacteria (AOB) and archaea (AOA). As this process has an absolute requirement for O2, the timing of its evolution—especially as it relates to the Great Oxygenation Event ~ 2.3 billion years ago—remains contested and is pivotal to our understanding of nutrient cycles. To estimate the antiquity of bacterial ammonia oxidation, we performed phylogenetic and molecular clock analyses of AOB. Surprisingly, bacterial ammonia oxidation appears quite young, with crown group clades having originated during Neoproterozoic time (or later) with major radiations occurring during Paleozoic time. These results place the evolution of AOB broadly coincident with the pervasive oxygenation of the deep ocean. The late evolution AOB challenges earlier interpretations of the ancient nitrogen isotope record, predicts a more substantial role for AOA during Precambrian time, and may have implications for understanding of the size and structure of the biogeochemical nitrogen cycle through geologic time.

Prerequisites for Processing a Foam Product in the Process of Bacterial Oxidation of Gold-Bearing Concentrates in a Separate Cycle

The recovery of gold from refractory ores and concentrates is a significant problem in the modern gold processing industry. The use of bacterial oxidation technology at the Navoi Mining and Metallurgical Combine (Uzbekistan) made it possible to increase the share of recoverable gold during the processing of refractory ores from the Kokpatas and Daugyztau deposits. However, during the operation of the biological installation, a problem arose of abundant foaming in bacterial oxidation reactors. This article is devoted to the issue of foaming during biooxidation and its negative impact on the oxidation process. Methods of combating foaming and the choice of the optimal solution, providing for the processing of bio-oxidation foam in a separate cycle, have been analyzed.

Bacterial nitric oxide metabolism: Recent insights in rhizobia.

Nitric oxide (NO) is a reactive gaseous molecule that has several functions in biological systems depending on its concentration. At low concentrations, NO acts as a signaling molecule, while at high concentrations, it becomes very toxic due to its ability to react with multiple cellular targets. Soil bacteria, commonly known as rhizobia, have the capacity to establish a N2-fixing symbiosis with legumes inducing the formation of nodules in their roots. Several reports have shown NO production in the nodules where this gas acts either as a signaling molecule which regulates gene expression, or as a potent inhibitor of nitrogenase and other plant and bacteria enzymes. A better understanding of the sinks and sources of NO in rhizobia is essential to protect symbiotic nitrogen fixation from nitrosative stress. In nodules, both the plant and the microsymbiont contribute to the production of NO. From the bacterial perspective, the main source of NO reported in rhizobia is the denitrification pathway that varies significantly depending on the species. In addition to denitrification, nitrate assimilation is emerging as a new source of NO in rhizobia. To control NO accumulation in the nodules, in addition to plant haemoglobins, bacteroids also contribute to NO detoxification through the expression of a NorBC-type nitric oxide reductase as well as rhizobial haemoglobins. In the present review, updated knowledge about the NO metabolism in legume-associated endosymbiotic bacteria is summarized.

Neem Coated Urea (NCU), An Efficient Nitrogen Source for Paddy Cultivation: A Review

Green revolution dramatically change the nitrogen application in paddy cultivation and day by day its demand increased but excessive and imbalanced use of nitrogen fertilizer has raised certain global concerns, also its low nitrogen use efficiency. Nitrogen is required in huge amounts for rice and supply of N in the right amount, at the right rate and at right time throughout the growing season is most important to increase the yield. Approximately 90% of the N-fertilizer applied worldwide is in the NH4+ form, which is rapidly oxidized to NO3- by soil nitrifier bacteria. Whereas, NCU temporarily delays the bacterial oxidation of the ammonium-nitrogen by depressing over a certain period of time the activity of Nitrosomonas bacteria in the soil. So far more than 75 studies have been conducted to study the performance of NCU in increasing the yield of rice and several other crops. In rice more than 30% of the urea consumed in India is applied, the mean increase in grain yield by replacing urea with NCU is 5 to 6%. NCU has been observed to improve nitrogen use efficiency and subsequently grain yield of rice. Possibly, applying NCU following the site-specific nutrient management principles will lead to paddy production of higher levels as observed with ordinary urea but with lower fertilizer application rates.

Research of the Application of Roasting in the Processing of the Foamy Product of the Process of Bacterial Oxidation of Flotation Concentrate in a Separate Cycle

Among the methods of preliminary opening of refractory gold before sorption cyanidation, the technology of bacterial oxidation is widely used today. Although this technology has many advantages, the specialists of most enterprises around the world using this technology are faced with the problem of foaming in bio-oxidation reactors. This article discusses the possibility of using oxidative roasting in the processing of the foam product of the process of bacterial oxidation of flotation concentrate in a separate cycle.

THE USE OF LIQUID SMOKE AS LATEX COAGULANT FOR RUBBER FARMER GROUP IN BUKIT LITI VILLAGE, CENTRAL KALIMANTAN

Bukit Liti Village is one of villages located in the Kahayan Tengah Sub-district, Pulang Pisau Regency, Central Kalimantan Province. Most people there tap rubber tree simply managed to produce bokar (rubber materials). In making bokar, rubber farmers use coagulant materials that can damage the rubber quality and soak bokar in water pool/creeks which lower the rubber quality and produce bad smell. To solve the problem, a training is conducted to make a simple pyrolysis reactor to produce liquid smoke which will be used as latex coagulant preventing and reducing bad smell and improving the bokar quality. Pyrolysis reactor is made from a used oil tank, and other materials with a thermometer to measure reactor temperature. The reactor is designed to allow a minimum oxygen combustion. The production of rubber wood liquid smoke for latex coagulation process in this research with 50 kg of old rubber wood materials has obtained 125 ml liquid smoke for 4-hour production time. The use of liquid smoke as latex coagulant gives real impacts for farmers such as: environmental friendly, to prevent bacterial growth and oxidation in the latex and latex lump, to prevent and reduce bad smells of bokar from the plantation, during storage and rubber processing in the rubber processing factory. The technology advantages of the liquid smoke are: faster coagulation, high elasticity, able to increase dry rubber content, relatively same price with other coagulant, to increase quality and selling price, produce clean latex and free of environment pollutant.

N2O and NOy production by the comammox bacterium Nitrospira inopinata in comparison with canonical ammonia oxidizers

Nitrous oxide (N2O) and NOy (nitrous acid (HONO) + nitric oxide (NO) + nitrogen dioxide (NO2)) are released as byproducts or obligate intermediates during aerobic ammonia oxidation, and further influence global warming and atmospheric chemistry. The ammonia oxidation process is catalyzed by groups of globally distributed ammonia-oxidizing microorganisms, which are playing a major role in atmospheric N2O and NOy emissions. Yet, little is known about HONO and NO2 production by the recently discovered, widely distributed complete ammonia oxidizers (comammox), able to individually perform the oxidation of ammonia to nitrate via nitrite. Here, we examined the N2O and NOy production patterns by comammox bacterium Nitrospira inopinata during aerobic ammonia oxidation, in comparison to its canonical ammonia-converting counterparts, representatives of the ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). Our findings, i) show low yield NOy production by the comammox bacterium compared to AOB; ii) highlight the role of the NO reductase in the biological formation of N2O based on results from NH2OH inhibition assays and its stimulation during archaeal and bacterial ammonia oxidations; iii) postulate that the lack of hydroxylamine (NH2OH) and NO transformation enzymatic activities may lead to a buildup of NH2OH/NO which can abiotically react to N2O ; iv) collectively confirm restrained N2O and NOy emission by comammox bacteria, an unneglectable consortium of microbes in global atmospheric emission of reactive nitrogen gases.

Spices as natural additives for beef burger production

Abstract This study aimed to investigate if the inclusion of different spices in bovine burger affects bacterial growth, lipid oxidation and sensorial characteristics of the products. Four hamburger formulations were prepared: control (without additives), saffron (1%), ginger (1%) and urucum (1%). The products were analyzed for total bacterial count (TBC) on days 0, 7 and 15 (storage at 4 °C) and 0, 15 and 60 (storage at -30 °C) and, for rancidity, on days 0, 30 and 60 (storage at -30 °C). The acceptance of the sensory attributes and the purchase intent were evaluated using hedonic scales. All burgers formulated with spices and kept at 4 °C had lower TBC than the control formulation, whereas for those stored at -30 °C, the same occurred only with the ginger-made ones. Lower lipid oxidation was found for the formulations containing the spices. Control and ginger formulations led the acceptance of the tasters for the attributes appearance and color, besides that, aroused greater interest in the purchase intention trial. It was concluded that the addition of spices reduced TBC and delayed the lipid oxidation of hamburgers, and that the products elaborated with ginger had the highest sensory acceptance and purchase intention indexes.

Influence of water quality on the autoclave leaching process (on the example of the Bereznyakovsky gold recovery factory)

For the first time this article provides a benchmarking analysis of water consumption while using modern technologies of gold recovery from ore; the best ore-processing technology for refractory sulphide ores is identified; and recommendations are given on water and energy saving in the process of autoclave leaching. The authors found that the most efficient technologies for extracting gold for certain geological conditions (gold is embedded in a complex mineral) are: autoclave leaching and bacterial oxidation. They allow you to save water resources, especially if these technologies use mills. The authors give recommendations for using the combined method. The calculation of surface runoff from the sites of the gold processing plant showed that using them, you can save from 3 to 8 percent of the make-up water.

Wastewater treatment by microalgal membrane bioreactor: Evaluating the effect of organic loading rate and hydraulic residence time

Current microalgal based photobioreactors focus on the secondary treated effluent while limited researches attempted for treating the raw domestic wastewater. This study aimed to assess the microalgal biomass production, removal performance, and fouling characteristics of microalgal membrane bioreactors (MMBRs) for treating synthetic wastewater under different conditions of organic loading rate (OLR) and hydraulic residence time (HRT). The 12h/12 h dark/light cycle continuous experiments were performed for four MMBRs at different OLRs and three MMBRs at different HRTs. Results showed that microalgal biomass production rate (as TSS and chlorophyll-a) decreased with increasing OLR and increased with decreasing of HRT. Regardless of the OLR and HRT conditions, MMBRs can achieve up to 94% organic removal by bacterial oxidation without external aeration. Total nitrogen (TN) and total phosphorus (TP) removals were significantly decreased with increasing OLR. Highest TN removal (68.4%) achieved at the OLR of 0.014 kg/(m3 d) which was reduced to 58.1% at 0.028 kg/(m3 d). Removals of total phosphorous significantly decreased from 48.2% to 37.7% with an increase in OLR from 0.011 to 0.014 kg/(m3 d). TN removal was reduced at shorten HRT (2 d), while, the effect of HRT was found insignificant at higher HRT. An effective removal of P can only be achieved at higher HRTs, i.e., 7 days. OLR up to 0.014 kg/(m3 d) and 2 days HRT was found suitable for maintaining the fouling frequency at an optimal level of 0.016/d. Overall the OLR and HRT need to be carefully selected to achieve optimal efficiency of MMBR. The results of this study provide guidelines for designing the microalgal-based membrane bioreactors for the treatment of domestic wastewater.