Bacterial Pretreatment Research Articles

Бактеріальна біоінокуляція як спосіб підвищення морфометричних показників однорічних сіянців сосни звичайної

За результатами дослідження встановлено, що бактеріальний штам P. abietaniphila є представником рістстимулювальних бактерій. Він проявив одну із ключових властивостей Plant Growth-Promoting Bacteria (PGPB), а саме здатність продукувати фітогормон ауксинової природи – індолілтриоцтову кислоту (ІОК) у кількості 85,06 мг на літр поживного середовища. З'ясовано, що ця властивість бактерій сприяє розвитку системної резистентності рослин та збільшенню морфофізіологічних показників проростків після біоінокуляції. Спостерігали за збільшенням довжин кореневих систем в однорічних сіянців, що попередньо інокулювалися з бактеріальним штамом P. abietaniphila на 57,7–58,7 %. Виявлено, що тенденція до збільшення довжини кореневої системи сіянців відобразилася на збільшенні сирої маси однорічних сіянців. Для дослідної групи, що обробляли суспензією з 109 КУО/мл, це значення становило 0,283 г, а для інокулянту з 108 КУО/мл – 0,210 г, тоді як для контрольної групи сіянців – 0,117 г. Загалом вдалося встановити, що загальна довжина інокульованих сіянців з бактеріальним штамом P. abietaniphila у всіх варіантах дослідження зростає завдяки збільшенню довжини кореневої системи. Проте з'ясовано, що оброблення 14-добових проростків суспензією, що містила 109 КУО/мл, спричинило збільшення довжини надземної частини однорічних сіянців на 20 %, порівняно з відповідним контролем. Результати наших досліджень свідчать, що бактеріальний штам P. abietaniphila потенційно покращить адаптацію сіянців сосни до природних умов середовища. Це свідчить про на перспективність використання його у практиці лісового господарства, для отримання високоякісних сіянців та саджанців сосни звичайної.

Effect of Dispersion Treatment on Dairy Waste Activated Sludge to Hasten the Production of Biogas

The solubilisation potential of biological pretreatment for waste activated sludge (WAS) is limited due to its floc structure. Extra polymeric substances (EPS) is responsible for floc formation. In this investigation, an attempt has been made to disturb floc structure of WAS by removing EPS through disperser. In first stage, disperser treatment released 242 mg/L of soluble EPS at 3000 rpm with the duration of the 50s and causes deflocculation of WAS. In second stage, deflocculated sludge was subjected to bacterial pretreatment to assess the effect of floc disruption. During bacterial pretreatment, it was found that deflocculated sludge produced higher organic solubilization of 23.9% and suspended solids reduction of 19.1%, when compared to control (10.2%) and (8.7%), respectively. A biogas yield of 220 mL/g COD was recorded in deflocculated sludge and 93 mL/g COD in flocculated sludge. From the above, it is evident that deflocculation effectively enhanced bacterial pretreatment leading to more solubilization and biogas production.

A hybrid treatment process for product recycling from tannery process effluent and soak liquor

The sulfate rich saline tannery effluent (SRSTE) was treated effectively using halophilic bacterial pretreatment followed by electrochemical oxidation (hybrid treatment). Aerobic degradation was done using halophilic bacterial consortia isolated from the tannery soak effluent, resulted in 76 % COD removal after 6 days. The remaining COD was reduced by electrochemical oxidation (EO). In electro oxidation process (without aerobic pretreatment), 24 h of electro-oxidation was needed to complete COD removal. The process efficiency was analysed through Fourier transform infrared spectroscopy (FTIR), high performance liquid chromatography (HPLC), total organic carbon (TOC) and chemical oxygen demand (COD). The reduction of sulfate could not be noticed in presence of halophilic bacteria in aerobic treatment. The energy consumption for COD removal was about 0.343 and 0.020 kW h/g1 in electrochemical oxidation and hybrid treatment process respectively. Besides, chloride loss was also higher in EO when compared to hybrid approach. Hybrid treatment process was proved to be an effective method for treating SRSTE. The mixed salt was recovered and used for dyeing purpose.

Bacterial pretreatment of paddy straw for enhancing biogas production

Bacterial pretreatment of paddy straw for enhancing biogas production

Aerobic bacterial pretreatment to overcome algal growth inhibition on high-strength anaerobic digestates

Coupling anaerobic digestion and algae cultivation has attracted attention as a sustainable means of treating high-strength wastewaters. In such a scenario, nutrients from the liquid anaerobic digestate are used by algae to produce biomass. However, use of full-strength digestate results in poor algal growth and nutrient removal. Most researchers have overcome this challenge by diluting digestate 10–30 fold prior to algae growth but such dilution rates demand large amounts of fresh water, posing challenges for scale-up. The objectives of this study were to 1) assess whether ammonium, turbidity, and heavy metals in digestate were the primary sources of inhibition for a highly-nutrient tolerant strain of Chlorella sorokiniana, and, 2) develop a biological pretreatment strategy to overcome algal growth inhibition on full strength digestate. Ammonia toxicity, turbidity, and heavy metals have been commonly hypothesized as the source of algal growth inhibition, but our results showed that these factors were not critical inhibitors of C. sorokiniana. Dose response studies showed that C. sorokiniana could grow robustly on 3,500 mg/L ammonium. Regardless, full strength digestates of wastewater sludge and food waste were very inhibitory to C. sorokiniana. We utilized a pretreatment approach using activated sludge which led to robust algal growth on full-strength digestate. High growth rates of 250–500 mg/L/d were achievable on pretreated digestates despite very high ammonium levels of ∼2,000 mg/L. Pretreating digestate also led to significantly faster algal nutrient uptake compared to untreated digestate (p < 0.001).

Enhanced digestion of bio-pretreated sawdust using a novel bacterial consortium: Microbial community structure and methane-producing pathways

Anaerobic digestion is widely considered the most cost effective and sustainable technology for bio-waste to energy valorization. Several substrates show a certain recalcitrance to the process evolution, such as sawdust. To this aim, in this study, sawdust has been subjected to a biological pretreatment by means of a novel bacterial consortium before its biomethanation. This novel lignocellulose-degrading bacterial consortium, isolated from several carpentries, has been constructed to predict the sawdust biological pretreatment efficacy. A five days bacterial pretreatment led to a significant reduction in the sawdust cellulose, hemicelluloses and lignin contents, towards the control, of 35.8, 37.1 and 46.2% respectively. Microbial diversity was analyzed by VIT® gene probe. Methanogenesis was carried out through acetoclastic and hydrogenotrophic pathways. For a forty days digestion time, the biological pretreatment enhanced the cumulative biogas and biomethane production respectively of 86.4 and 92.2% compared to the control. With respect to the state of art, the use of this constructed novel consortium pretreatment can significantly increase the biomethane yield, making the digestion more effective and consequently improving the processes economic feasibility. Moreover, this process can be easily integrated in existing biogas plants for making co-digestion processes still more elastic with regard to the available feedstock.

Effect of low intensity sonic mediated fragmentation of anaerobic granules on biosurfactant secreting bacterial pretreatment: Energy and mass balance analysis

In this study, fragmentation of anaerobic granules (AG) was carried out by low intensity sonification (LIS) to release its extracellular polymeric substance (EPS). The experimental outcome of the study shows that 30 s treatment time and 60 W sonic power was effective for fragmentation of AG. The fragmented anaerobic granules were further subjected to pretreatment by biosurfactant secreting bacteria. Bacterial pretreatment achieves a maximum biogranules lysis of 20.3% and biosolids reduction of 17.1% for fragmented anaerobic granules bacterial pretreatment (FAG-BP). Whereas for bacterial pretreatment (BP) alone, it achieves 10.9% and 8.6% of biogranules lysis and biosolids reduction respectively. Exponential first order kinetic model of biomethane production data revealed greater biomethane production for FAG-BP (0.247 g COD/g COD) than BP (0.131 g COD/g COD). Cost analysis of FAG mediated bacterial pretreatment results in a net profit of 48.606 USD/Ton.

The production of cellulase from the waste tobacco residues remaining after polyphenols and nicotine extraction and bacterial pre-treatment

Agricultural by-products are generated in large amounts in various industries, creating a serious disposal problem. Valorisation of tobacco waste for the extraction of value-added compounds and the production of enzymes could reduce both the problems of its disposal and the costs of cellulase production. Hitherto, there have been no reported studies concerning the utilization of tobacco residues (after extraction of polyphenols and nicotine, and fermentation pre-treatment by Streptomyces fulvissimus CKS7) for the production of cellulase (CMCase and ?vicelase) by Paenibacillus chitinolyticus CKS1. The optimal conditions for the polyphenols and nicotine extraction process were obtained using the response surface methodology: 60 s extraction time in water and 30 mL g-1 liquid/solid ratio. After the applied bacterial fermentation as a pre-treatment of tobacco residues, using Paenibacillus species, the extraction of polyphenols decreased by up to 10 %, while the extraction of nicotine increased by up to 35 %. Afterward, the maximum of cellulase activities (CMCase of 0.878 U g-1 and avicelase of 1.417 U g-1) were achieved using of the strain CKS1.

Use of bacteria for improving the lignocellulose biorefinery process: importance of pre-erosion

BackgroundBiological pretreatment is an important alternative strategy for biorefining lignocellulose and has attracted increasing attention in recent years. However, current designs for this pretreatment mainly focus on using various white rot fungi, overlooking the bacteria. To the best of our knowledge, for the first time, we evaluated the potential contribution of bacteria to lignocellulose pretreatment, with and without a physicochemical process, based on the bacterial strain Pandoraea sp. B-6 (hereafter B-6) that was isolated from erosive bamboo slips. Moreover, the mechanism of the improvement of reducing sugar yield by bacteria was elucidated via analyses of the physicochemical changes of corn stover (CS) before and after pretreatment.ResultsThe digestibility of CS pretreated with B-6 was equivalent to that of untreated CS. The recalcitrant CS surface provided fewer mediators for contact with the extracellular enzymes of B-6. A pre-erosion strategy using a tetrahydrofuran–water co-solvent system was shown to destroy the recalcitrant CS surface. The optimal condition for pre-erosion showed a 6.5-fold increase in enzymatic digestibility compared with untreated CS. The pre-erosion of CS can expose more phenolic compounds that were chelated to oxidized Mn3+ and also provided mediators for combination with laccase, which was attributable to B-6 pretreatment. B-6 pretreatment following pre-erosion exhibited a sugar yield that was 91.2 mg/g greater than that of pre-erosion alone and 7.5-fold higher than that of untreated CS. This pre-erosion application was able to destroy the recalcitrant CS surface, thus leading to a rough and porous architecture that better facilitated the diffusion and transport of lignin derivatives. This enhanced the ability of laccase and manganese peroxidase secreted by B-6 to improve the efficiency of this biological pretreatment.ConclusionBacteria were not found useful alone as a biological pretreatment, but they significantly improved enzymatic digestion after lignocellulose breakdown via other physicochemical methods. Nonetheless, phenyl or phenoxy radicals were used by laccase and manganese peroxidase in B-6 for lignin attack or lignin depolymerization. These particular mediators released from the recalcitrance network of lignocellulose openings are important for the efficacy of this bacterial pretreatment. Our findings thus offer a novel perspective on the effective design of biological pretreatment methods for lignocellulose.

Bioethanol production using vegetable peels medium and the effective role of cellulolytic bacterial (Bacillus subtilis) pre-treatment.

Background: The requirement of an alternative clean energy source is increasing with the elevating energy demand of modern age. Bioethanol is considered as an excellent candidate to satiate this demand. Methods: Yeast isolates were used for the production of bioethanol using cellulosic vegetable wastes as substrate. Efficient bioconversion of lignocellulosic biomass into ethanol was achieved by the action of cellulolytic bacteria ( Bacillus subtilis). After proper isolation, identification and characterization of stress tolerances (thermo-, ethanol-, pH-, osmo- & sugar tolerance), optimization of physiochemical parameters for ethanol production by the yeast isolates was assessed. Very inexpensive and easily available raw materials (vegetable peels) were used as fermentation media. Fermentation was optimized with respect to temperature, reducing sugar concentration and pH. Results: It was observed that temperatures of 30°C and pH 6.0 were optimum for fermentation with a maximum yield of ethanol. The results indicated an overall increase in yields upon the pretreatment of Bacillus subtilis; maximum ethanol percentages for isolate SC1 obtained after 48-hour incubation under pretreated substrate was 14.17% in contrast to untreated media which yielded 6.21% after the same period. Isolate with the highest ethanol production capability was identified as members of the ethanol-producing Saccharomyces species after stress tolerance studies and biochemical characterization using Analytical Profile Index (API) ® 20C AUX and nitrate broth test. Introduction of Bacillus subtilis increased the alcohol production rate from the fermentation of cellulosic materials. Conclusions: The study suggested that the kitchen waste can serve as a raw material in ethanol fermentation.

Bioethanol production using vegetable peels medium and the effective role of cellulolytic bacterial (Bacillus subtilis) pre-treatment

Background: The requirement of an alternative clean energy source is increasing with the elevating energy demand of modern age. Bioethanol is considered as an excellent candidate to satiate this demand. Methods: Yeast isolates were used for the production of bioethanol using cellulosic vegetable wastes as substrate. Efficient bioconversion of lignocellulosic biomass into ethanol was achieved by the action of cellulolytic bacteria ( Bacillus subtilis). After proper isolation, identification and characterization of stress tolerances (thermo-, ethanol-, pH-, osmo- & sugar tolerance), optimization of physiochemical parameters for ethanol production by the yeast isolates was assessed. Very inexpensive and easily available raw materials (vegetable peels) were used as fermentation media. Fermentation was optimized with respect to temperature, reducing sugar concentration and pH. Results: It was observed that temperatures of 30°C and pH 6.0 were optimum for fermentation with a maximum yield of ethanol. The results indicated an overall increase in yields upon the pretreatment of Bacillus subtilis; maximum ethanol percentages for isolate SC1 obtained after 48-hour incubation under pretreated substrate was 14.17% in contrast to untreated media which yielded 6.21% after the same period. Isolate with the highest ethanol production capability was identified as members of the ethanol-producing Saccharomyces species after stress tolerance studies and biochemical characterization using Analytical Profile Index (API) ® 20C AUX and nitrate broth test. Introduction of Bacillus subtilis increased the alcohol production rate from the fermentation of cellulosic materials. Conclusions: The study suggested that the kitchen waste can serve as a raw material in ethanol fermentation.

Nano‐layered TiO2 for effective bacterial disintegration of waste activated sludge and biogas production

AbstractBACKGROUNDProper management of the huge amount of waste activated sludge generated during the conventional treatment of wastewater is nowadays a major environmental issue. Proper treatment of sludge needs huge investment and proper handling. To address this issue, the immobilized photocatalyst (TiO2) mediated exocellular fractionation of bacterial pretreatment for anaerobic digestion was utilized as a sludge treatment technique.RESULTTi was deposited on glass substrate by a DC spluttering technique, and a TiO2 layer was formed by annealing in oxygen atmosphere. This immobilized TiO2 efficiently extricated the extracellular components after 45 min by removing 99% of the total extractable extracellular polymeric substances. The exocellular fractionated bacterial pretreatment induced 20% of COD solubilization with methane generation of about 0.0217 g COD g‐1 COD d‐1, which was higher than the sludge without any treatment and sludge with bacterial pretreatment only.CONCLUSIONAn 8% increase in COD solubilization was achieved, which generated high quantities of methane. With the advantage of methane generation, the maximum profitable sludge reduction was obtained. Thin film deposition of TiO2 enables easy recovery of TiO2. The cost, energy, and solid balance analysis confirmed that this treatment method is field applicable. © 2018 Society of Chemical Industry

Ethanol production using vegetable peels medium and the effective role of cellulolytic bacterial (Bacillus subtilis) pre-treatment.

Background: The requirement of an alternative clean energy source is increasing with the elevating energy demand of modern age. Bioethanol is considered as an excellent candidate to satiate this demand. Methods: Yeast isolates were used for the production of bioethanol using cellulosic vegetable wastes as substrate. Efficient bioconversion of lignocellulosic biomass into ethanol was achieved by the action of cellulolytic bacteria ( Bacillus subtilis). After proper isolation, identification and characterization of stress tolerances (thermo-, ethanol-, pH-, osmo- & sugar tolerance), optimization of physiochemical parameters for ethanol production by the yeast isolates was assessed. Very inexpensive and easily available raw materials (vegetable peels) were used as fermentation media. Fermentation was optimized with respect to temperature, reducing sugar concentration and pH. Results: It was observed that temperatures of 30°C and pH 6.0 were optimum for fermentation with a maximum yield of ethanol. The results indicated an overall increase in yields upon the pretreatment of Bacillus subtilis; maximum ethanol percentages for isolate SC1 obtained after 48-hour incubation under pretreated substrate was 14.17% in contrast to untreated media which yielded 6.21% after the same period. Isolate with the highest ethanol production capability was identified as members of the ethanol-producing Saccharomyces species after stress tolerance studies and biochemical characterization using Analytical Profile Index (API) ® 20C AUX and nitrate broth test. Introduction of Bacillus subtilis increased the alcohol production rate from the fermentation of cellulosic materials. Conclusions: The study suggested that the kitchen waste can serve as an excellent raw material in ethanol fermentation.

Enhancing digestibility of Miscanthus using lignocellulolytic enzyme produced by Bacillus

In this study an effective bacterial pretreatment method was developed to improve digestibility of Miscanthus. Seven new bacterial isolates, which showed excellent xylanase production ability using Miscanthus as carbon source, were used to perform the pretreatment experiments. After pretreatment, the hemicellulose content and crystallinity index of Miscanthus were decreased, while the reducing sugars released from Miscanthus were significantly increased by 30.8–87.8% after enzymatic hydrolysis. Bacillus sp. G0 was selected to optimize the pretreatment parameters via response surface methodology due to its high reducing sugars released from Miscanthus. According to the optimal model, the pretreatment parameters were set as citrate buffer/G0 fermentation broth ratio at 0.34, pretreatment time at 100h and Tween-20 concentration at 1.73%. The reducing sugars released from Miscanthus pretreated by optimal parameters were 305mgg−1 dry biomass. The results suggested our bacterial pretreatment approaches have great potential to increase digestibility of bioenergy crops.

Influence of Thermal and Bacterial Pretreatment of Microalgae on Biogas Production in Mesophilic and Thermophilic Conditions.

Microalgae biomass has a great potential in search for new alternative energy sources. They can be used as a substrate for the biogas production in anaerobic digestion. When using microalgae, the efficiency of this process is hampered due to the resistant cell wall. In order to accelerate the hydrolysis of cell wall and increase the efficiency of biogas production we applied two different pretreatments - biological and thermal under mesophilic and thermophilic conditions. During biological pretreatment we incubated microalgae with anaerobic hydrolytic bacteria Pseudobutyrivibrio xylanivorans Mz5T. In thermal pretreatment we incubated microalgae at 90 °C. We also tested a combined thermal and biological pretreatment in which we incubated P. xylanivorans Mz5T with thermally pretreated microalgae. Thermal pretreatment in mesophilic and thermophilic process has increased methane production by 21% and 6%, respectively. Biological pretreatment of microalgae has increased methane production by 13%, but only under thermophilic conditions (pretreatment under mesophilic conditions showed no effect on methane production). Thermal-biological pretreatment increased methane production by 12% under thermophilic conditions and by 6% under mesophilic conditions.

Enhancement of biogas production from microalgal biomass through cellulolytic bacterial pretreatment

Generation of bioenergy from microalgal biomass has been a focus of interest in recent years. The recalcitrant nature of microalgal biomass owing to its high cellulose content limits methane generation. Thus, the present study investigates the effect of bacterial-based biological pretreatment on liquefaction of the microalga Chlorella vulgaris prior to anaerobic biodegradation to gain insights into energy efficient biomethanation. Liquefaction of microalgae resulted in a higher biomass stress index of about 18% in the experimental (pretreated with cellulose-secreting bacteria) vs. 11.8% in the control (non-pretreated) group. Mathematical modelling of the biomethanation studies implied that bacterial pretreatment had a greater influence on sustainable methane recovery, with a methane yield of about 0.08 (g Chemical Oxygen Demand/g Chemical Oxygen Demand), than did control pretreatment, with a yield of 0.04 (g Chemical Oxygen Demand/g Chemical Oxygen Demand). Energetic analysis of the proposed method of pretreatment showed a positive energy ratio of 1.04.

Biodegradation of terpenes for emission-reduced oriented strand boards (OSB)

Abstract A bacterial mixture of Pseudomonas putida and Pseudomonas fluorescens has recently shown the potential to completely reduce monoterpenes within pine wood particles on a laboratory scale. This bacterial combination was then applied onto pine wood strands to obtain emission-reduced oriented strand boards (OSB) produced on a technical scale. Laboratory tests with bacterial inoculated strands were carried out to optimise parameters such as aeration and incubation time. Residual terpene emissions were measured by solid-phase microextraction/ gas chromatography-mass spectrometry (SPME/GC-MS) analysis. Daily aeration, specific pre-cultivation, and increased inoculum size eventually resulted in a reduction of the major softwood terpenes α-pinene, β-pinene, and Δ3-carene by 60, 70, and 40%, respectively, after only 2 days of incubation. Based on these results, OSB were manufactured from strands after bacterial pre-treatment for 2 or 4 days. As expected, terpene emissions from OSB decreased with increasing incubation time. However, even after only 2 days of incubation, α-pinene and β-pinene emissions were appreciably reduced by 40 and 70%, respectively. The method developed here thus appears to be feasible for industrial application although a further reduction of pre-treatment time would be advantageous. The inoculation step will also have to be adapted for technical implementation into the OSB production process.

Upgrading the hydrolytic potential of immobilized bacterial pretreatment to boost biogas production.

In this study, surfactant dioctyl sodium sulphosuccinate (DOSS)-mediated immobilized bacterial pretreatment of waste activated sludge (WAS) was experimentally proved to be an efficient and economically feasible process for enhancing the biodegradability of WAS. The maximal floc disruption with negligible cell cleavage was achieved at surfactant dosage of 0.009g/g SS. Results of the outcome of bacterial pretreatment of sludge biomass revealed that chemical oxygen demand (COD) solubilization for deflocculated (EPS removed-bacterially pretreated) sludge was 20%, which was higher than that of flocculated (14%) or control (5%). The pretreatment was swift in deflocculated sludge with a rate constant of about 0.064h-1. Biochemical methane potential (BMP) assay resulted in significant methane yield at 0.24 gCOD/gCOD for deflocculated sludge. Economic assessment of the proposed method showed a net profit of about 57.39 USD/ton of sludge.

Effect of bacterial amylase pretreatment on bioethanol production from starch-based solid waste (SBSW)

ABSTRACTFuels derived from biomass are essential in order to overcome the excessive dependence on petroleum. They also minimize the emissions of greenhouse gases. Pretreatment in biofuel production is a very important step. Pretreatment is not only costly in its own right but also has a pervasive impact on the cost of virtually all other processing operations. The present study investigates the effect of bacterial amylase pretreatment on ethanol production from different kinds of starch-based solid waste (SBSW). For this purpose four amylase-producing bacterial isolates were obtained from samples collected from municipal waste dumping sites. The isolated bacteria were then used for the pretreatment of SBSW for ethanol production. After bacterial amylase pretreatment, 13% yield of ethanol was obtained.

Effect of bacterial amylase pretreatment on alcohol production from starch-based solid waste

ABSTRACTA number of different pretreatments involving biological, chemical, physical, and thermal approaches have been investigated over the years to reduce the cost of biofuel production. This study investigates the effect of bacterial amylase pretreatment on bioethanol production from different kinds of starch-based solid waste. We have isolated one strain (Xenorhabdus japonica) of amylase-producing bacteria from municipal waste dumping site's soil. Maximum ethanol yield was obtained after bacterial amylase pretreatment from wheat bread and rice (132 g/L), while the minimum was obtained from potato (99 g/L). Bacterial amylase pretreatment shows the best results as compared to the acid pretreatment.