Algal-bacterial Culture Research Articles

Euglena mutabilis exists in a FAB consortium with microbes that enhance cadmium tolerance

BackgroundSynthetic algal–fungal and algal–bacterial cultures have been investigated as a means to enhance the technological applications of the algae. This inclusion of other microbes has enhanced growth and improved stress tolerance of the algal culture. The goal of the current study was to investigate natural microbial consortia to gain an understanding of the occurrence and benefits of these associations in nature. The photosynthetic protist Euglena mutabilis is often found in association with other microbes in acidic environments with high heavy metal (HM) concentrations. This may suggest that microbial interactions are essential for the protist’s ability to tolerate these extreme environments. Our study assessed the Cd tolerance of a natural fungal–algal–bacterial (FAB) association whereby the algae is E. mutabilis.ResultsThis study provides the first assessment of antibiotic and antimycotic agents on an E. mutabilis culture. The results indicate that antibiotic and antimycotic applications significantly decreased the viability of E. mutabilis cells when they were also exposed to Cd. Similar antibiotic treatments of E. gracilis cultures had variable or non-significant impacts on Cd tolerance. E. gracilis also recovered better after pre-treatment with antibiotics and Cd than did E. mutabilis. The recoveries were assessed by heterotrophic growth without antibiotics or Cd. In contrast, both Euglena species displayed increased chlorophyll production upon Cd exposure. PacBio full-length amplicon sequencing and targeted Sanger sequencing identified the microbial species present in the E. mutabilis culture to be the fungus Talaromyces sp. and the bacterium Acidiphilium acidophilum.ConclusionThis study uncovers a possible fungal, algal, and bacterial relationship, what we refer to as a FAB consortium. The members of this consortium interact to enhance the response to Cd exposure. This results in a E. mutabilis culture that has a higher tolerance to Cd than the axenic E. gracilis. The description of this interaction provides a basis for explore the benefits of natural interactions. This will provide knowledge and direction for use when creating or maintaining FAB interactions for biotechnological purposes, including bioremediation.

The interactions between microalgae and wastewater indigenous bacteria for treatment and valorization of brewery wastewater

This study aims to elucidate the changes in indigenous bacterial composition in four different microalgal cultures and compare brewery wastewater treatment efficiency, amino and fatty acids content of the four microalgal systems with and without indigenous bacteria. 16S rRNA gene sequences indicate that microalgae affect the bacterial community composition. The chemical oxygen demand (COD) removal efficiency was significantly higher in algal-bacterial culture (>80%) compared with algal culture (40%), and different bacterial compositions did not change COD removal for four algal species. C. vulgaris showed the highest TN (>94%) and TP removal capability among the four species. No significant differences in TN removal were found between mixed and algal cultures. Again, indigenous bacteria did not cause significant differences in TP removal except for C. vulgaris. Besides, the influence of indigenous brewery bacteria on the concentration of different amino and fatty acids in algal biomass was algal species-dependent.

The impact of light intensity and wavelength on the performance of algal-bacterial culture treating domestic wastewater

Light is the main energy source for microalgae, and the intensity and wavelength of light influence cell metabolism and biomass composition, which, in turn, affects wastewater treatment. The objective of this study is to examine how different light intensities and light wavelengths affect the growth of mixed algal-bacterial culture while treating sewage. Three different light intensities (100, 200, and 300 μmol/m2-s) of four different light wavelengths (blue, red, white, and yellow) were selected for this study. The dissolved organic carbon (DOC), dissolved nitrogen (DN), and dissolved phosphorus (DP) in influent and effluent samples were measured, along with chlorophyll content in the biomass. The highest chlorophyll concentration of 3.5 mg/L was observed at 100 μmol/m2-s intensity of red light. The concentration of chlorophyll decreased as light intensity increased, with exception of white light. The highest DOC removal of 84% was observed at 300 μmol/m2-s intensity of blue light whereas the highest DN (51%) and DP (80%) removal was observed with a red light intensity of 100 μmol/m2-s. Overall, blue light with an intensity of 300 μmol/m2-s and red light with an intensity of 100 μmol/m2-s were found to be the most efficient at removing carbon and nutrients. The results suggested that the color and intensity of light influence algal-bacterial growth and wastewater treatment efficiency.

Novel photo-microrespirometric method for the rapid determination of photosynthesis-irradiance (PI) curves in microalgal-bacterial systems

Photoreactors are now largely used in a span of applications but are complex systems that would still benefit from a better constraint of their kinetic behaviour. Among others, the determination of the Photosynthetic-Irradiance (PI) curve in photoreactors, which describes the correlation between light irradiance and activity of the algal or algal-bacterial culture, is of utmost importance for modelling, optimization, and control purposes. Habitually, PI curves in photoreactors are determined through incubation done under a range of irradiance, and even if many remarkable advances have been achieved in the methods applied, there is still a need for a simple, robust, polyvalent and fast method. We present here a method based on a modified respirometer, commercially available, that allows to measure the dissolved oxygen production/uptake, simultaneously in 24 replicates under a controlled irradiance. This so-called photo-microrespirometric method, was applied successfully to the determination of PI curves of a microalgal-bacterial culture obtained from a pilot-scale pond treating the liquid fraction of an anaerobic digestate. The PI curves obtained, in a few hours of experimental work, were well fitted by the Bernard-Rémond's kinetic model. In addition to PI curves, the method allowed for the quantification of the inhibitory effect of dissolved oxygen as well as the response time of the photoactivation and photoinhibition.

Microalgae-based removal of contaminants of emerging concern: Mechanisms in Chlorella vulgaris and mixed algal-bacterial cultures

Incomplete removal of contaminants of emerging concern (CECs) has been reported for conventional wastewater treatment technologies. Microalgae-based treatment has recently gained interest thanks to simultaneous removal capacity of organic and inorganic compounds and potentially CECs. In this study, a lab-scale monoculture of Chlorella vulgaris and mixed microalgal-bacterial culture were compared in terms of removal of 28 CECs (bisphenols, 2018 EU Watch List substances, including neonicotinoids, pharmaceuticals, selected transformation products). The removal pathways in light and dark abiotic controls were also studied. Batch photobioreactors were run at hydraulic retention times of 11–12 days and CECs spiked at environmentally relevant concentrations (1–20 μg L−1). The mixed culture was better at removing bisphenols, compared to C. vulgaris. Bisphenols’ log Kow was significant in removal pathways, where bisphenols with high log Kow were removed abiotically while bisphenols with low log Kow were mainly biodegraded. The removal degrees and the pathways of pharmaceuticals and EU Watch List substances were comparable between both cultures, showing no impact of log Kow for most compounds; however, the removal with C. vulgaris was faster for some. High log Kow was associated with high removal of estradiol in abiotic controls, showing the importance of adsorption onto biomass and suspended matter.

Enhancement of productivity of Chlorella pyrenoidosa lipids for biodiesel using co-culture with ammonia-oxidizing bacteria in municipal wastewater

As one of the most promising renewable energy, microalgal biodiesel has been widely studied worldwide. However, the low-efficiency of conventional microalgae cultivation procedures restrict the development of microalgae biodiesel production. Microalgal-bacterial symbiosis could both enhance the growth of algal-bacterial culture and promote the removal and conversion of wastewater nutrients. In this study, three strains of high-efficient heterotrophic ammonia-oxidizing bacteria JN1, FN3, and FN5 were screened from municipal wastewater treatment system with over 80% degradation rates of 50 mg/L ammonia-nitrogen (NH3–N) in 24 h. Among them, FN5, belonging to Kluyvera sp., had the optimum effect on enhancing growth of oil-rich microalga Chlorella pyrenoidosa. In stationary phase, the biomass and lipid content of Chlorella pyrenoidosa was14.8% and 13.6% higher than the blank control tests without FN5. In contrast, JN1 and FN3 failed to enhance the growth of Chlorella pyrenoidosa. After the cultivation of Chlorella pyrenoidosa-FN5 consortia in municipal wastewater, the degradation rate of NH3–N was up to 91% while the content of microalgae biomass and lipid attained 0.35 g/L and 39.0%. The Saturated fatty acids (SFAs), Monounsaturated fatty acids (MUFAs), and Polyunsaturated fatty acids (PUFAs) were 43.9, 37.1 and 19.0%, respectively, which had the potential for biodiesel production after pretreatment.

Nutrient, Linear Alkyl Benzene Sulfonate, and Caffeine Removal from Synthetic Wastewater with an Algal–bacterial Culture and an Activated Sludge Culture in Batch Mode

Nutrient, Linear Alkyl Benzene Sulfonate, and Caffeine Removal from Synthetic Wastewater with an Algal–bacterial Culture and an Activated Sludge Culture in Batch Mode

Preliminary study of algasidal activities of the episymbiont bacterial consortium from Enhalus acoroides

Seagrass symbiotic bacteria have various functions, one of which is as algaside. There are 2 types of symbionts namely endosymbiont and episymbiont. This study aims to test the initial activity of algaside episymbiont Enhalus acoroides on diatome and dinoflagellate group plankton. The method used for testing is Mixed Algal-bacterial cultures. On media that has been overgrown with algae will be inoculated with episymbiont bacterial consortium E. acoroides. The results of the bacterial consortium research have not shown significant algaside activity. But, on Nitschia sp. showed significant algaside activity. This mean specific activity in the compound or mechanism used as algaside.

Ethyl tert-butyl ether (EtBE) degradation by an algal-bacterial culture obtained from contaminated groundwater

EtBE is a fuel oxygenate that is synthesized from (bio)ethanol and fossil-based isobutylene, and replaces the fossil-based MtBE. Biodegradation of EtBE to harmless metabolites or end products can reduce the environmental and human health risks after accidental release. In this study, an algal-bacterial culture enriched from contaminated groundwater was used to (i) assess the potential for EtBE degradation, (ii) resolve the EtBE degradation pathway and (iii) characterize the phylogenetic composition of the bacterial community involved in EtBE degradation in contaminated groundwater. In an unamended microcosm, algal growth was observed after eight weeks when exposed to a day-night light cycle. In the fed-batch reactor, oxygen produced by the algae Scenedesmus and Chlorella was used by bacteria to degrade 50 μM EtBE replenishments with a cumulative total of 1250 μM in a day/night cycle (650 lux), over a period of 913 days. The microbial community in the fed-batch reactor degraded EtBE, using a P450 monooxygenase and 2-hydroxyisobutyryl-CoA mutase, to tert-butyl alcohol (TBA), ethanol and CO2 as determined using 13C nuclear magnetic resonance spectroscopy (NMR) and gas chromatography. Stable isotope probing (SIP) with 13C6 labeled EtBE in a fed-batch vessel showed no significant difference in community profiles of the 13C and 12C enriched DNA fractions, with representatives of the families Halomonadaceae, Shewanellaceae, Rhodocyclaceae, Oxalobacteraceae, Comamonadaceae, Sphingomonadaceae, Hyphomicrobiaceae, Candidatus Moranbacteria, Omnitrophica, Anaerolineaceae, Nocardiaceae, and Blastocatellaceae. This is the first study describing micro-oxic degradation of EtBE by an algal-bacterial culture. This algal-bacterial culture has advantages compared with conventional aerobic treatments: (i) a lower risk of EtBE evaporation and (ii) no need for external oxygen supply in the presence of light. This study provides novel leads towards future possibilities to implement algal-bacterial consortia in field-scale groundwater or wastewater treatment.

Factors influencing algal photobiohydrogen production in algal-bacterial co-cultures

Algal-bacterial co-cultures represent an alternative way for algal biohydrogen generation. Efficient algal hydrogen production requires anaerobiosis and electrons accessible for the algal FeFe‑hydrogenases. A number of factors strongly influence the development of this optimal environment. Various algal strains were tested for hydrogen evolution with a selected bacterial partner, a fully hydrogenase deficient Escherichia coli. During the hunt for the most efficient algae strains, gas-to-liquid phase ratio, algal optical density and algal cell size were identified as crucial factors influencing algal hydrogen evolution rate, accumulated algal hydrogen yield, carbon dioxide and oxygen levels as well as acetic acid consumption in illuminated algal-bacterial cultures. The highest accumulated hydrogen yields were observed for the different algal partners under similar experimental setup. The combination of a gas-to-liquid phase ratio of 1/1 with an algae cell density of 3.96∗108 algae cellml−1 (OD750: 1) resulted in the highest accumulated algal hydrogen yields under continuous illumination of ~50μmolm−2s−1 light at 25°C irrespective of the applied algae strain. Accumulated hydrogen yield was also strongly influenced by the algal cell size, smaller cell size correlated with higher hydrogen evolution rate. The highest accumulated algal hydrogen yield (88.98±2.19mlH2l−1d−1) was obtained with Chlorella sp. MACC 360 -E. coli ΔhypF co-culture.

Effects of influent C/N ratios and treatment technologies on integral biogas upgrading and pollutants removal from synthetic domestic sewage

Three different treatment technologies, namely mono-algae culture, algal-bacterial culture, and algal-fungal culture, were applied to remove pollutants form synthetic domestic sewage and to remove CO2 from biogas in a photobioreactor. The effects of different initial influent C/N ratios on microalgal growth rates and pollutants removal efficiencies by the three microalgal cultures were investigated. The best biogas upgrading and synthetic domestic sewage pollutants removal effect was achieved in the algal-fungal system at the influent C/N ratio of 5:1. At the influent C/N ratio of 5:1, the algal-fungal system achieved the highest mean chemical oxygen demand (COD) removal efficiency of 81.92% and total phosphorus (TP) removal efficiency of 81.52%, respectively, while the algal-bacterial system demonstrated the highest mean total nitrogen (TN) removal efficiency of 82.28%. The average CH4 concentration in upgraded biogas and the removal efficiencies of COD, TN, and TP were 93.25 ± 3.84% (v/v), 80.23 ± 3.92%, 75.85 ± 6.61%, and 78.41 ± 3.98%, respectively. These results will provide a reference for wastewater purification ad biogas upgrading with microalgae based technology.

Efficiency of lipid accumulating Actinomycetes isolated from soil for biodiesel production: Comparative study with microalgae

ABSTRACT Due to the global warming and the increase of toxic gases emitted from the fossil fuels and the increase of energy demand, it is necessary to look for alternative sources for biodiesel. In this work, fifty bacterial species were isolated from soil samples and the isolated bacteria were tested for their ability of lipid production. The most potent lipid producer was identified as Streptomyces coelicolor A3-NC:003888.3 using the 16S rDNA partial sequencing technique. The lipid production process was performed in a bench scale for pure S. coelicolor, Chlorella vulgaris (as a standard biodiesel producer) and mixed algal bacterial culture as a comparative study. The results indicated that 93% wt of fatty acids of Streptomyces was converted to the corresponding fatty acid methyl esters (biodiesel). After transesterification of the produced lipids, the obtained oil was characterized according to American Society for Testing and Materials (ASTM) standards. The density of bacterial biodiesel was 0.866 and that of algal biodiesel was 0.797; also the specific gravity was 0.866 and 0.784 for bacterial and algal biodiesel, respectively, giving more lubricant characters for bacterial biodiesel. The gross heating value of bacterial biodiesel (43426 Kj/Kg) was higher than that of algal biodiesel (41896 Kj/Kg), dependently, the cetane number of bacterial biodiesel (38) was little lower than that of algal biodiesel (43).

Algal-bacterial process for the simultaneous detoxification of thiocyanate-containing wastewater and maximized lipid production under photoautotrophic/photoheterotrophic conditions.

In this work, a cooperative algal-bacterial system that efficiently degrades thiocyanate (SCN(-)), a toxic contaminant, and exhibits high lipid productivity, was developed. A consortium of mixed bacteria (activated sludge) and microalgae was sequentially cultivated under photoautotrophic and photoheterotrophic modes. The hydrolysis of SCN(-) to ammonium (NH4(+))-nitrogen and subsequent nitrification steps were performed by the initial activated sludge under lithoautotrophic conditions. The NH4(+) and oxidized forms of nitrogen, nitrite (NO2(-)) and nitrate (NO3(-)), were then assimilated and removed by the microalgal cells when light was supplied. After the degradation of SCN(-), the cultivation mode was changed to photoheterotrophic conditions in a sequential manner. Algal-bacterial cultures containing Chlorella protothecoides and Ettlia sp. yielded significantly increased lipid productivity under photoheterotrophic conditions compared to photoautotrophic conditions (28.7- and 17.3-fold higher, respectively). Statistical methodologies were also used to investigate the effects of volatile fatty acids and yeast extract on biomass and lipid production.

Simulated sugar factory wastewater remediation kinetics using algal–bacterial raceway reactor promoted by Polyacrylate polyalcohol

The remediation kinetics of simulated sugar factory wastewater (SFW) using an algal-bacterial culture (ABC) of Chlorella vulgaris in association with Pseudomonas putida in a raceway reactor was found to be enhanced by 89% with the addition of 80ppm of copolymer Polyacrylate polyalcohol (PAPA). This was achieved by efficient suspension of the ABC throughout the water body maintaining optimum pH and dissolved oxygen that led to rapid COD removal and improved algal biomass production. The suspension of the ABC using the co-polymer PAPA maintained a DO of 8-10mgl(-1) compared to 2-3mgl(-1) when not suspended. As a result, the non-suspended ABC only achieved a 50% reduction in COD after 96h compared to a 89% COD removal using 80ppm PAPA suspension. In addition, the algae biomass increased from 0.4gl(-1)d(-1) for the non-suspended ABC to 1.1gl(-1)d(-1) when suspended using 80ppm PAPA.

Effect of bacteria from the bottom water layer of lake baikal on degradation of diatoms

Among isolates of the eubacteria Brevundimonas bullata, Sphingomonas rhizogenes, Agrobacterium tumefaciens, Bacillus simplex, Acinetobacter johnsonii, Methylobacterium adhaesivum, and Deinococcus aquaticus isolated from the bottom layer on the medium, where the only source of organic matter was hydrolysate from diatoms, the activity of hydrolytic enzymes, such as proteases, β-xylosidase, β-glucosidase, β-galactosidase, chitobiase, and amylase, is revealed. An algicidal effect and degradation of siliceous diatom frustules are recorded in algal-bacterial cultures. These data show that the bottom water layer of Lake Baikal is inhabited by potential participants of silicon cycle, which degrade siliceous valves of diatoms.

Synergistic cooperation between wastewater-born algae and activated sludge for wastewater treatment: Influence of algae and sludge inoculation ratios

An algal–bacterial culture, composed of wastewater-born algae and activated sludge, was cultivated to treat domestic wastewater and accumulate biomass simultaneously. The influence of algae and sludge inoculation ratios on the treatment efficiency and the settleability of the accumulated biomass were investigated. There was no significant effect of the inoculation ratios on the chemical oxygen demand removal. Comparatively, the nutrients removal and related mechanism were varied with different inoculation ratios. The highest nitrogen and phosphorus removal efficiencies were observed with 5:1 (algae/sludge) culture (91.0 ± 7.0% and 93.5 ± 2.5%, respectively) within 10 days, which was 5–40% higher and 2–4 days faster than those with other inoculation ratios. The biomass settleability was improved with the assistance of sludge, and the 1:5 (algae/sludge) culture showed the best settleability. Furthermore, 16S rDNA gene analysis showed that the bacterial communities were varying with different algae and sludge inoculation ratios and some specific bacteria were enriched during operation.

Municipal wastewater treatment and biomass accumulation with a wastewater-born and settleable algal-bacterial culture

A wastewater-born and settleable algal-bacterial culture, cultivated in a stirred tank photobioreactor under lab conditions, was used to remove the carbon and nutrients in municipal wastewater and accumulate biomass simultaneously. The algal-bacterial culture showed good settleable property and could totally settle down over 20 min, resulting in a reduction of total suspended solids from an initial 1.84 to 0.016 g/l. The average removal efficiencies of chemical oxygen demand, total kjeldahl nitrogen and phosphate were 98.2 ± 1.3%, 88.3 ± 1.6% and 64.8 ± 1.0% within 8 days, respectively, while the average biomass productivity was 10.9 ± 1.1 g/m 2·d. Accumulation into biomass, identified as the main nitrogen and phosphorus removal mechanism, accounted for 44.9 ± 0.4% and 61.6 ± 0.5% of total inlet nitrogen and phosphorus, respectively. Microscopic analysis showed the main algae species in the bioreactor were filamentous blue-green algae. Furthermore, denaturing gradient gel electrophoresis and 16S rDNA gene sequencing revealed that the main bacteria present in the photobioreactor were consortia with sequences similar to those of Flavobacteria, Gammaproteobacteria, Bacteroidia and Betaproteobacteria. This study explores a better understanding of an algae-bacteria system and offers new information on further usage of biomass accumulated during treatment.

Microbial Formation of Manganese Oxides

Microbial manganese oxidation was demonstrated at high Mn concentrations (5 g/liter) in bacterial cultures in the presence of a microalga. The structure of the oxide produced varied depending on the bacterial strain and mode of culture. A nonaxenic, acid-tolerant microalga, a Chlamydomonas sp., was found to mediate formation of manganite (gamma-MnOOH). Bacteria isolated from associations with crude cultures of this alga grown in aerated bioreactors formed disordered gamma-MnO(2) from Mn at concentrations of 5 g/liter over 1 month, yielding 3.3 g of a semipure oxide per liter. All algal-bacterial cultures removed Mn from solution, but only those with the highest removal rates formed an insoluble oxide. While the alga was an essential component of the reaction, a Pseudomonas sp. was found to be primarily responsible for the formation of a manganese precipitate. Medium components-algal biomass and urea-showed optima at 5.7 and 10 g/liters, respectively. The scaled-up culture (50 times) gave a yield of 22.3 g (53 mg/liter/day from a 15-liter culture) of semipure disordered gamma-MnO(2), identified by X-ray diffraction and Fourier transform infrared (FTIR) spectroscopy, and had a manganese oxide O/Mn ratio of 1.92. The Mn(IV) content in the oxide was low (30.5%) compared with that of mined or chemically formed gamma-MnO(2) (ca. 50%). The shortfall in the bacterial oxide manganese content was due to biological and inorganic contaminants. FTIR spectroscopy, transmission electron microscopy, and electron diffraction studies have identified manganite as a likely intermediate product in the formation of disordered gamma-MnO(2).

Oxygen balance in micro stabilization ponds

In a continuous flow of domestic sewage, the effect of various environmental conditions on the oxygen balance of an algal-bacterial culture was studied in 2 microponds in series. The relation between the size of the algal population and the amount of photosynthetic oxygen was discussed.

Closed Ecological Systems

Long term life support requires the use of a closed ecological system. The attainable degree of closure is determined by the extent of conversion achieved in the waste recovery system. Organisms used in such systems must be reliable, useful, and integrable. Strictly speaking, a completely closed ecological system implies a photosynthetic component, because oxygen is produced biologically only through photosynthesis. However, the same result can be attained by substituting electrolysis of water for photosynthesis in the production of oxygen. Photosynthetic systems generally have algae as the green plants, whereas nonphotosynthetic systems use bacteria of the genus Hydrogenomanas as the key organism. An integrated life support system consisting of a mammal (mouse or mice), algae, and bacteria, and named Microterella by the writers, was developed and used by the writers to demonstrate that closed ecological systems (in the strict sense) are suitable for life support in space. The development of the Algatron, a growth unit of which a mechanically rotated algal-bacterial culture is an essential feature, considerably enhances the practical feasibility of the Microterella system.