Formaldehyde-limited cultivation of a newly isolated methylotrophic bacterium, Methylobacterium sp. MF1: enzymatic analysis related to C1 metabolism

Endophyte-assisted non-host plant Tillandsia brachycaulos enhance indoor formaldehyde removal

This study investigated the use of endophyte-assisted Tillandsia brachycaulos to enhance formaldehyde removal in indoor environments. A formaldehyde-degrading endophyte from the root of Epipremnum aureum, Pseudomonas plecoglossicida, was identified and used for inoculation. Among the inoculation methods, spraying proved to be the most effective, resulting in a significant 35 % increase in formaldehyde removal after 36 hours. The results of the light exposure experiment (3000 Lux) demonstrate that an increase in light intensity reduces the efficiency of the Tillandsia brachycaulos-microbial system in degrading formaldehyde. In a 15-day formaldehyde fumigation experiment at 2 ppm in a normal indoor environment, the inoculated Tillandsia brachycaulos exhibited removal efficiency ranging from 42.53 % to 66.13 %, while the uninoculated declined from 31.62 % to 3.17 %. The Pseudomonas plecoglossicida (referred to as PP-1) became the predominant bacteria within the Tillandsia brachycaulos after fumigation. Moreover, the endophytic inoculation effectively increased the resistance and tolerance of Tillandsia brachycaulos to formaldehyde, as evidenced by lower levels of hydroxyl radical, malondialdehyde (MDA), free protein, and peroxidase activity (POD), as well as higher chlorophyll content compared to uninoculated Tillandsia brachycaulos. These findings indicate that the combination of endophytic bacteria and Tillandsia brachycaulos has significant potential for improving indoor air quality.

An orthogonal metabolic framework for one-carbon utilization

Metabolic engineering often entails concurrent engineering of substrate utilization, central metabolism and product synthesis pathways, inevitably creating interdependency with native metabolism. Here we report an alternative approach using synthetic pathways for C1 bioconversion that generate multicarbon products directly from C1 units and hence are orthogonal to the host metabolic network. The engineered pathways are based on formyl-CoA elongation (FORCE) reactions catalysed by the enzyme 2-hydroxyacyl-CoA lyase. We use thermodynamic and stoichiometric analyses to evaluate FORCE pathway variants, including aldose elongation, α-reduction and aldehyde elongation. Promising variants were prototyped in vitro and in vivo using the non-methylotrophic bacterium Escherichia coli. We demonstrate the conversion of formate, formaldehyde and methanol into various products including glycolate, ethylene glycol, ethanol and glycerate. FORCE pathways also have the potential to be integrated with the host metabolism for synthetic methylotrophy by the production of native growth substrates as demonstrated in a two-strain co-culture system.

Biotechnology progress for removal of indoor gaseous formaldehyde

Formaldehyde is a ubiquitous carcinogenic indoor pollutant. The treatment of formaldehyde has attracted increasing social attention. Over the past few decades, an increasing number of publications have reported approaches for removing indoor formaldehyde. These potential strategies include physical adsorption, chemical catalysis, and biodegradation. Although physical adsorption is widely used, it does not really remove pollution. Chemical catalysis is very efficient but adds the risk of introducing secondary pollutants. Biological removal strategies have attracted more research attention than the first two methods, because it is more efficient, clean, and economical. Plants and bacteria are the common organisms used in formaldehyde removal. However, both have limitations and shortcomings when used alone. This review discusses the mechanisms, applications, and improvements of existing biological methods for the removal of indoor gaseous formaldehyde. A combination strategy relying on plants, bacteria, and physical adsorbents exhibits best ability to remove formaldehyde efficiently, economically, and safely. When this combination system is integrated with a heating, ventilation, air conditioning, and cooling (HVAC) system, a practical combined system can be established in formaldehyde removal. Multivariate interactions of biological and non-biological factors are needed for the future development of indoor formaldehyde removal. KEY POINTS: • Indoor gaseous formaldehyde removal is necessary especially for new residence. • Biological removal strategies have attracted increasing research attentions. • Combined system of plants, bacteria, and physical adsorbents exhibits best efficiency. • Integrated device of biological and non-biological factors will be potential practical.

Gaseous Formaldehyde Degrading by Methylobacterium sp. XJLW

Formaldehyde is harmful to human beings. It is widely used in chemical industry, medicine, and agriculture and is frequently discharged into the sewage. Microbial metabolism of formaldehyde has attracted increasing attention for its potential application in formaldehyde removal, especially for indoor gaseous formaldehyde degradation. Methylobacterium sp. XJLW capable of degrading formaldehyde was isolated and exhibited a strong activity for liquid formaldehyde degradation. In the present study, the survival rate of XJLW was evaluated under drought, 30 °C, 4 °C, 15 °C, 35 °C, and 40 °C. After 4 days, the average survival rate under 30°C is the greatest (83.97%) among the five temperatures. Whether the temperature was above or below 30°C, the average survival rate decreased significantly. However, the resistance of XJLW to reduced temperatures seemed better than that to increased temperatures. The average survival rate under 15°C and 4°C was 71.1% and 58.67%, while that under 35 °C and 40 °C was 49.47% and 0.1%. Two batches of gaseous formaldehyde treatments were carried out in an analog device with super absorbent polymer (SAP) as the carrier materials of XJLW. The results showed that XJLW could effectively degrade gaseous formaldehyde in the analog device for a long period.

Biodegradation of high concentrations of formaldehyde by lyophilized cells of Methylobacterium sp. FD1

In the present study, Methylobacterium sp. FD1 utilizing formaldehyde was isolated from soil. The resting cells of FD1 degraded high concentrations of formaldehyde (~2.7 M) and produced formic acid and methanol that were molar equivalents of one-half of the degraded formaldehyde. This result suggests that formaldehyde degradation by FD1 is caused by formaldehyde dismutase. The optimal temperature and pH for formaldehyde degradation by the resting cells of FD1 were 40 °C and 5–7, respectively. The lyophilized cells of FD1 also degraded high concentrations of formaldehyde. The formaldehyde degradation activity of the lyophilized cells was maintained as the initial activity at 25 °C for 287 days. These results suggest that the lyophilized cells of FD1 are useful as formaldehyde degradation materials.

Requirement of carbon dioxide for initial growth of facultative methylotroph, Acidomonas methanolica MB58

The facultative methylotrophic bacterium Acidomonas methanolica MB58 can utilize C1 compounds via the ribulose monophosphate pathway. A large gene cluster comprising three components related to C1 metabolism was found in the genome. From upstream, the first was an mxa cluster encoding proteins for oxidation of methanol to formaldehyde; the second was the rmp cluster encoding enzymes for formaldehyde fixation; and the third was the cbb gene cluster encoding proteins for carbon dioxide (CO2) fixation. Examination of CO2 requirements for growth of A. methanolica MB58 cells demonstrated that it did not grow on any carbon source under CO2-free conditions. Measurement of ribulose-1,5-bisphosphate carboxylase activity and RT-PCR analysis demonstrated enzymatic activity was detected in A. methanolica MB58 at growth phase, regardless of carbon sources. However, methanol dehydrogenase and 3-hexlose-6-phosphate synthase expression was regulated by methanol or formaldehyde; it were detected during growth and apparently differed from ribulose-1,5-bisphosphate carboxylase expression. These results suggested that A. methanolica MB58 may be initially dependent on autotrophic growth and that carbon assimilation was subsequently coupled with the ribulose monophosphate pathway at early- to mid-log phases during methylotrophic growth.

Formaldehyde biodegradation by immobilized Methylobacterium sp. XJLW cells in a three-phase fluidized bed reactor

In the present study, the ability of a newly isolated strain, Methylobacterium sp. XJLW to degrade formaldehyde was investigated in shake flasks and in a bioreactor. The resting cells of Methylobacterium sp. XJLW showed high formaldehyde tolerance (60 g L(-1)) and high degradation rate (1,687.5 mg L(-1) h(-1)) in shake flasks. This biodegradation was initiated by a dismutation reaction since formic acid was formed and caused significant dropping of pH in the media. The addition of CaCO(3) to the media was found as an effective strategy to control the pH and keep the cells in high degradation bioactivity. A three-phase fluidized bed reactor (TPFBR) was designed to test the formaldehyde-biodegrading ability of immobilized Methylobacterium sp. XJLW. Using a repeated-batch degradation mode, the immobilized cells were able to degrade 5 g L(-1) formaldehyde (with a maximal degradation rate of 464.5 mg L(-1) h(-1) under the optimum conditions) and showed stable bioactivity after 20 batches of reuse in the TPFBR.

Effect of a static magnetic field of 7 mT on formaldehyde biodegradation in industrial wastewater from urea-formaldehyde resin production by activated sludge

The goal of this study was to assess the efficiency of treating industrial urea-formaldehyde wastewater by activated sludge in a static magnetic field (MF) of 7 mT and the efficiency of treating the wastewater in a bioreactor not exposed to an MF. Exposure to the MF increased formaldehyde (FA) removal from industrial wastewater with an FA concentration of 1600 mg/l by 20%. The MF had also a positive effect on the efficiency of chemical oxygen demand (COD) removal, and bacteria and activated sludge biomass growth, especially when the COD loading increased rapidly. Industrial wastewater may contain up to 13000 mg FA/l. Therefore, its treatment can require the application of more than one method to ensure that the final FA concentration will be within the permissible limit. The application of an MF to enhance the biological processes may be favourable solution to this problem.

Synthesis and characterization of a biodegradable polymer prepared viaradical copolymerization of 2-(acetoacetoxy)ethyl methacrylate and molecular oxygen

We describe the synthesis and characterization of a biodegradable and biocompatible polymeric peroxide, poly[2-(acetoacetoxy)ethyl methacrylate] peroxide.

Effect of a static magnetic field on formaldehyde biodegradation in wastewater by activated sludge

The aim of this study was to determine the impact of a static magnetic field (MF) of 7 mT on formaldehyde (FA) biodegradation by activated sludge in synthetic wastewater. The MF had a positive effect on activated sludge biomass growth and dehydrogenase activity. The influence of the MF on the degradation process was observed with a FA concentration of 2400-2880 mg/l. Decreases in FA concentration and chemical oxygen demand (COD) were greater, by 30% and 26% respectively, than those in the control sample. At initial FA concentrations in raw wastewater of 2400 and 2880 mg/l, a decrease in the wastewater biodegradation efficiency was observed. This resulted in an increase of the ecotoxicity of the effluent to Daphnia magna. The value of the sludge biotic index (SBI) was dependent on the FA concentration in raw wastewater and the induction of the MF.

C(1) compounds as auxiliary substrate for engineered Pseudomonas putida S12

The solvent-tolerant bacterium Pseudomonas putida S12 was engineered to efficiently utilize the C₁ compounds methanol and formaldehyde as auxiliary substrate. The hps and phi genes of Bacillus brevis, encoding two key steps of the ribulose monophosphate (RuMP) pathway, were introduced to construct a pathway for the metabolism of the toxic methanol oxidation intermediate formaldehyde. This approach resulted in a remarkably increased biomass yield on the primary substrate glucose when cultured in C-limited chemostats fed with a mixture of glucose and formaldehyde. With increasing relative formaldehyde feed concentrations, the biomass yield increased from 35% (C-mol biomass/C-mol glucose) without formaldehyde to 91% at 60% relative formaldehyde concentration. The RuMP-pathway expressing strain was also capable of growing to higher relative formaldehyde concentrations than the control strain. The presence of an endogenous methanol oxidizing enzyme activity in P. putida S12 allowed the replacement of formaldehyde with the less toxic methanol, resulting in an 84% (C-mol/C-mol) biomass yield. Thus, by introducing two enzymes of the RuMP pathway, co-utilization of the cheap and renewable substrate methanol was achieved, making an important contribution to the efficient use of P. putida S12 as a bioconversion platform host.