Innovative production of value-added products using agro-industrial wastes via solid-state fermentation.

The prevalence of organic solid waste worldwide has turned into a problem that requires comprehensive treatment on all fronts. The amount of agricultural waste generated by agro-based industries has more than triplet. It not only pollutes the environment but also wastes a lot of beneficial biomass resources. These wastes may be utilized as a different option/source for the manufacturing of many goods, including biogas, biofertilizers, biofuel, mushrooms and tempeh as the primary ingredients in numerous industries. Utilizing agro-industrial wastes as good raw materials may provide cost reduction and lower environmental pollution levels. Agro-industrial wastes are converted into biofuels, enzymes, vitamin supplements, antioxidants, livestock feed, antibiotics, biofertilizers and other compounds via solid-state fermentation (SSF). By definition, SSF is a method used when there is little to no free water available. As a result, it permits the use of solid materials as biotransformation substrates. Through SSF methods, a variety of microorganisms are employed to produce these worthwhile things. SSFs are therefore reviewed and discussed along with their impact on the production of value-added items. This review will provide thorough essential details information on recycling and the use of agricultural waste.

Development of novel kinetic model based on microbiome and biochar for in-situ remediation of total petroleum hydrocarbons (TPHs) contaminated soil.

A novel kinetic model has been developed to explain the degradation of total petroleum hydrocarbons. Microbiome engineered biochar amendment may result in a synergistic impact on degradation of total petroleum hydrocarbons (TPHs). Therefore, the present study analyzed the potential of hydrocarbon-degrading bacteria A designated as Aeromonas hydrophila YL17 and B as Shewanella putrefaciens Pdp11 morphological characterized as rod shaped, anaerobic and gram-negative immobilized on biochar, and the degradation efficiency was measured by gravimetric analysis and gas chromatography-mass spectrometry (GC-MS). Whole genome sequencing of both strains revealed the existence of genes responsible for hydrocarbon degradation. In 60 days remediation setup, the treatment consisting of immobilization of both strains on biochar proved more efficient with less half-life and better biodegradation potentials compared to biochar without strains for decreasing the content of TPHs and n-alkanes (C12-C18). Enzymatic content and microbiological respiration showed that biochar acted as a soil fertilizer and carbon reservoir and enhanced microbial activities. The removal efficiency of hydrocarbons was found to be a maximum of 67% in soil samples treated with biochar immobilized with both strains (A + B), followed by biochar immobilized with strain B 34%, biochar immobilized with strain A 29% and with biochar 24%, respectively. A 39%, 36%, and 41% increase was observed in fluorescein diacetate (FDA) hydrolysis, polyphenol oxidase and dehydrogenase activities in immobilized biochar with both strains as compared to control and individual treatment of biochar and strains. An increase of 35% was observed in the respiration rate with the immobilization of both strains on biochar. While a maximum colony forming unit (CFU/g) was found 9.25 with immobilization of both strains on biochar at 40 days of remediation. The degradation efficiency was due to synergistic effect of both biochar and bacteria based amendment on the soil enzymatic activity and microbial respiration.

Treatment technologies for olive mill wastewater with impacts on plants.

Olive mill wastewater (OMW), produced during olive oil production, contains high levels of salt contents, organic matter, suspended particles, and toxic chemicals (particularly phenols), which all result in increased biological and chemical oxygen demand. Olive Oil Mills' Wastes (OMW), which have dark brown color with unpleasant smell, consist mainly of water, high organic (mainly phenols and polyphenols) and low inorganic compounds (e.g. potassium and phosphorus), as well as grease. OMW components can negatively affect soil's physical, chemical, and biological properties, rendering it phytotoxic. However, OMW can positively affect plants' development when it's applied to the soil after pretreatment and treatment processes due to its high mineral contents and organic matter. There are various approaches for removing impurities and the treatment of OMW including chemical, biological, thermal, physiochemical, and biophysical processes. Physical techniques involve filtration, dilution, and centrifugation. Thermal methods include combustion and pyrolysis; biological techniques use anaerobic and aerobic techniques, whereas adsorption and electrocoagulation act as physiochemical methods, and coagulation and flocculation as biophysical methods. In contrast, combined biological treatment methods use co-digestion and composting. A comparison of the effects of both treated and untreated OMW samples on plant development and soil parameters can help us to understand the potential role of OMW in increasing soil fertility. This review discusses the impacts of untreated OMW and treated OMW in terms of soil characteristics, seed germination, and plant growth. This review summarizes all alternative approaches and technologies for pretreatment, treatment, and recovery of valuable byproducts and reuse of OMW across the world.

Comparison of pennywort and hyacinth in the development of membraned sediment plant microbial fuel cell for waste treatment.

Membraned Sediment Plant Microbial Fuel cells (SPMFCs) are appealing bioelectrochemical systems that generate power from organic compounds in sediment through exoelectrogen decomposition and are used to treat wastewater. This research was designed to develop a single-chambered sediment plant microbial fuel cell using two membrane electrodes; one carbon plate cathode and one anode. Wastewater and sediment mixture was sampled from Rawalpindi, Pakistan, and bacterial isolation was performed by serial dilution. Five strains were selected on the basis of morphology and growth-promoting characteristics. The selected strains were identified by 16s rRNA sequencing and designated as A (Geobacter sulfurreducens OP527025), B (Shawanella putrefaciens OP522353), C (Bacillus subtilus OP522349), D (Azospirillum humicireducens OP527050) and E (Pseudomonas putida OP526951). Consortium of five strains was developed. Two aquatic plants pennyworts (Hydrocotyle umbellate), and Hyacinth (Eichhornia crassipes) were used in the SPMFCs along with consortium. A maximum voltage of 1120mv was observed in SPMFCs treated with the consortium and water hyacinth, which was followed by 543.3 mv of SPMFCs treated with water pennyworts. Physicochemical analysis of wastewater showed a remarkable reduction of 74.5%, 71%, and 76% in nitrate, phosphate, and sulphate content of wastewater treated with microbes and water hyacinth. The heavy metal analysis showed a reduction of Zn (99.8%), Mg (99.9%), and Ni (98.4%) in SPMFCs treated with the consortium and water hyacinth. Mebraned SPMFCs showed an increase of 30% and 20% in shoot and root length of water hyacinth. A remarkable increase of 25%, 18%, and 12% were recorded in chlorophyll content, membrane stability index and relative water content of water hyacinth in SPMFCs treated with consortium compared to untreated cells. Osmolyte content had shown significant increase of 25% with consortium treated water hyacinth plant as compared to untreated one. An increase of 15%, 20% and 12% was noted in superoxide dismutase (SOD), peroxidase dismutase (POD) and catalase content of consortium treated water hyacinth as compared to control one. The present research gave insight into the potential of sediment plant microbial fuel cells along with aquatic plants for treatment of wastewater. This could be a effective method for removal of hazrdaous substances from wastewater and alternative approach for voltage production.

Advances in Biochar and PGPR engineering system for hydrocarbon degradation: A promising strategy for environmental remediation.

In soil, polycyclic aromatic hydrocarbons (PAHs) have resulted in severe environmental deterioration, compromised soil characteristics, and negatively affect all life forms, including humans. Developing appropriate and effective clean-up technology is crucial in solving the contamination issues. The traditional methods to treat PHAs contaminated soil are less effective and not ecofriendly. Bioremediation, based on bioaugmentation and biostimulation approaches, is a promising strategy for remediating contaminated soil. The use of plant growth-promoting rhizobacteria (PGPR) as a bioaugmentation tool is an effective technique for treating hydrocarbon contaminated soil. Plant growth-promoting rhizobacteria (PGPR) are group of rhizospheric bacteria that colonize the roots of plants. Biochar is a carbon-rich residue, which acts as a source of nutrients, and is also a bio-stimulating candidate to enhance the activities of oil-degrading bacteria. The application of biochar as a nutrient source to bioremediate oil-contaminated soil is a promising approach for reducing PHA contamination. Biochar induces polyaromatic hydrocarbons (PAHs) immobilization and removes the contaminants by various methods such as ion exchange electrostatic attractions and volatilization. In comparison, PGPR produce multiple types of biosurfactants to enhance the adsorption of hydrocarbons and mineralize the hydrocarbons with the conversion to less toxic substances. During the last few decades, the use of PGPR and biochar in the bioremediation of hydrocarbons-contaminated soil has gained greater importance. Therefore, developing and applying a PGPR-biochar-based remediating system can help manage hazardous PAH contaminated soil. The goal of this review paper is to (i) provide an overview of the PGPR mechanism for degradation of hydrocarbons and (ii) discuss the contaminants absorbent by biochar and its characteristics (iii) critically discuss the combined effect of PGPR and biochar for degradation of hydrocarbons by decreasing their mobility and bioavailability. The present review focuses on techniques of bioaugmentation and biostimulation based on use of PGPR and biochar in remediating the oil-contaminated soil.

Biodegradation of PAHs by Bacillus marsiflavi, genome analysis and its plant growth promoting potential.

The biodegradation of hazardous petroleum hydrocarbons has recently received a lot of attention because of its many possible applications. Bacillus marsiflavi strain was isolated from oil contaminated soil of Rawalpindi, Pakistan. Initial sequencing was done by 16s rRNA sequencing technique. Bac 144 had shown 78% emulsification index and 72% hydrophobicity content. Further, the strain displayed production of 15.5 mg/L phosphate sloubilization and 30.25 µg/ml indole acetic acid (IAA) in vitro assay. The strain showed 65% biodegradation of crude oil within 5 days by using Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Whole Genome analysis of Bac 144 was performed by PacBio sequencing and results indicated that Bacillus marsiflavi Bac144 strain consisted of size of 4,417,505bp with closest neighbor Bacillus cereus ATCC 14579. The number of the coding sequence was 4662 and number of RNAs was 141. The GC content comprised 48.1%. Various genes were detected in genome responsible for hydrocarbon degradation and plant defense mechanism. The toxic effect of petroleum hydrocarbons in soil and its mitigation with Bac 144 was tested by soil experiment with three levels of oil contamination (5%, 10% and 15%). Soil enzymatic activity such as dehydrogenase and fluorescein diacetate (FDA) increased up to 49% and 40% with inoculation of Bac 144, which was considered to be correlated with hydrocarbon degradation recorded as 46%. An increase of 20%, 14% and 9% in shoot length of plant at 5%, 10% and 15% level of oil was recorded treated with Bac 144 as compared to untreated plants. A percent increase of 14.89%, 16.85%, and 13.87% in chlorophyll, carotenoid, and proline content of plant was observed by inoculation with Bac 144 under oil stress. Significant reduction of 14% and 18%, 21% was recorded in the malondialdehyde content of plant due to inoculation of Bac 144. A considerable increase of 21.33%, 19.5%, and 24.5% in super oxide dismutase, catalase, and peroxidase dismutase activity was also observed in plants inoculated with strain Bac 144. These findings suggested that Bac-144 can be considered as efficient candidate for bioremediation of hydrocarbons.

Biostimulation potential of biochar for remediating the crude oil contaminated soil and plant growth.

Crude oil contamination is a serious environmental threat to soil and plants growing in it. Biochar has the potential of biostimulation for remediation of crude oil-contaminated soil. Therefore, the current research was designed to analyze the bio-stimulatory impact of biochar for remediating the crude oil contaminated soil (10%, and 15%), and growth of maize under glasshouse conditions. Biochar was produced by pyrolysis of Australian pines at 350 °C. Soil incubations were done for 20 days. The results of soil analysis showed that the crude oil degradation efficiency of biochar was 34%. The soil enzymatic activities had shown 38.5% increase in fluorescein diacetate (FDA) hydrolysis and 55.6% increase in dehydrogenase activity in soil incubated with biochar in comparison to control. The soil microbial diversity was improved to 41% in biochar treated soil with respect to untreated one, while microbial respiration rate had shown a 33.67% increase in soil incubated with biochar with respect to control under oil stress. Gas Chromatography Mass spectrometry (GC-MS) analysis had shown the high content of low molecular weight hydrocarbons (C9-C13) in the soil incubated with biochar in comparison to untreated soil. Biochar showed a significant increase in fresh and dry biomass (25%, 14.61%), leaf area (10%), total chlorophyll (11%), water potential (21.6%), osmotic potential (21%), and membrane stability index (12.7%). Moreover, biochar treatment showed a higher increase in the contents of proline (29%), total amino acids (18%), soluble sugars (30.4%), and antioxidant enzymes like superoxide dismutase (16.5%), catalase (11%), and peroxidase (12%). Overall, the results of the present study suggest the bio-stimulating potential of biochar for degradation of hydrocarbons in crude oil contaminated soil and their growth-stimulating effects on maize.

Comparison of plant growth and remediation potential of pyrochar and thermal desorption for crude oil-contaminated soils.

Crude oil contamination is a serious environmental threat for soil and plants growing in it. This study provides the first experimental evidence for comparison of the efficacy of pyrochar (slow pyrolysis biochar), thermal desorption and their combined application for degradation of crude oil contaminated soil (0%, 10%, and 20%), and growth of lettuce under glasshouse conditions. Pyrochar was produced by pyrolysis of sawdust at 350 °C, whereas thermal desorption was done by soil pyrolysis at 500 °C. Soil incubations were done for 120 days. The results of soil analysis showed that the crude oil degradation efficiency for the combined application was highest (40%), whereas pyrochar and thermal desorption was 25% and 19.6%, respectively. The maximum degradation products of crude oil were manifested by the detection of low molecular weight hydrocarbons (ranged between 173 and 422) in the soil with combined application treatment using Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Crude oil contamination significantly reduced the germination and growth of the lettuce plants. Similarly, the combined application also improved plant growth by an increase of 24% in germination percentage, 35.5% in seedling vigor index, and 27% in promptness index under 20% crude oil contamination. Remediation caused a significant increase in fresh and dry biomass (40%), leaf area (30%), total chlorophyll (21%), water potential (23.6%), osmotic potential (27%), and membrane stability index (40%). Moreover, there was an increase in the contents of proline (32%), total amino acids (29%), soluble sugars (37%), proteins (27%), and antioxidant enzymes such as superoxide dismutase (19%), catalase (33%) and peroxidase (38%). This study confirmed the efficacy of pyrochar (slow pyrolysis biochar), thermal desorption, and their combined application for crude oil decontamination of soil at laboratory scale and also in improving soil usability by improved germination and growth of lettuce.