Solid waste management techniques powered by in-silico approaches with a special focus on municipal solid waste management: Research trends and challenges.

Many technical, climatic, environmental, biological, financial, educational, and regulatory factors are typically involved in solid waste management (SWM). Artificial Intelligence (AI) techniques have lately gained attraction in providing alternative computational methods for resolving problems of solid waste management. The purpose of this review is to direct solid waste management researchers taking an interest in the use of artificial intelligence in their area of study through main research elements such as AI models, their own benefits and drawbacks, effectiveness, and applications. The major AI technologies recognized are discussed in the subsections of the review, which contains a specific fusion of AI models. It also covers research that equated AI technologies to other non-AI methodologies. The section that follows contains a brief debate of the numerous SWM disciplines where AI was consciously applied. The article concludes with progress, challenges and perspectives in implementing AI-based solid waste management.

A reduction in temperature induces bioactive red pigment production in a psychrotolerant Penicillium sp. GEU_37 isolated from Himalayan soil.

Filamentous fungi are being globally explored for the production of industrially important bioactive compounds including pigments. In the present study, a cold and pH tolerant fungus strain Penicillium sp (GEU_37), isolated from the soil of Indian Himalaya, is characterized for the production of natural pigments as influenced by varying temperature conditions. The fungal strain produces a higher sporulation, exudation, and red diffusible pigment in Potato Dextrose (PD) at 15 °C as compared to 25 °C. In PD broth, a yellow pigment was observed at 25 °C. While measuring the effect of temperature and pH on red pigment production by GEU_37, 15 °C and pH 5, respectively, were observed to be the optimum conditions. Similarly, the effect of exogenous carbon and nitrogen sources and mineral salts on pigment production by GEU_37 was assessed in PD broth. However, no significant enhancement in pigmentation was observed. Chloroform extracted pigment was separated using thin layer chromatography (TLC) and column chromatography. The two separated fractions i.e., fractions I and II with Rf values 0.82 and 0.73, exhibited maximum light absorption, λmax, at 360 nm and 510 nm, respectively. Characterization of pigments using GC-MS showed the presence of the compounds such as phenol, 2,4-bis (1,1-dimethylethyl) and eicosene from fraction I and derivatives of coumarine, friedooleanan, and stigmasterole in fraction II. However, LC-MS analysis detected the presence of derivatives of compound carotenoids from fraction II as well as derivative of chromenone and hydroxyquinoline as major compounds from both the fractions along with other numerous important bioactive compounds. The production of such bioactive pigments under low temperature conditions suggest their strategic role in ecological resilience by the fungal strain and may have biotechnological applications.

Comparative study of bacterial community dynamics in different soils following application of the herbicide atrazine.

Microbial communities in cultivated soils control the fate of pollutants associated with agricultural practice. The present study was designed to explore the response of bacterial communities to the application of the widely-used herbicide atrazine in three different crop fields that differ significantly in their physicochemical structure and nutritional content: the nutrient-rich (with relatively high carbon and nitrogen content) Newe Yaar (NY) and Ha-Ogen (HO) soils and the nutrient-poor, sandy Sde-Eliyahu (SE) soil. The 16 S rRNA gene amplicon sequencing revealed the nutrient poor HO soil differs in its response to atrazine in comparison to the two nutrient-rich soils both in the shortest persistence of atrazine and its effect on community structure and composition. Potential reported bacterial degraders of atrazine such as Pseudomonas, Clostridium and Bacillus were more abundant in contaminated sandy/poor soils (HO) whereas bacteria known for nitrogen cycling such as Azospirillum, Sinorhizobium, Nitrospira and Azohydromonas were significantly more abundant in the nutrient rich contaminated SE soils. No significant increase of potential indigenous degrader Arthrobacter was detected in SE and NY soils whereas a significant increase was recorded with HO soils. An overall shift in bacterial community composition following atrazine application was observed only in the nutrient poor soil. Understanding atrazine persistence and microbiome response to its application of in dependence with soil types serve the design of precision application strategies.

Modeling-Guided Amendments Lead to Enhanced Biodegradation in Soil.

Extensive use of agrochemicals is emerging as a serious environmental issue coming at the cost of the pollution of soil and water resources. Bioremediation techniques such as biostimulation are promising strategies used to remove pollutants from agricultural soils by supporting the indigenous microbial degraders. Though considered cost-effective and eco-friendly, the success rate of these strategies typically varies, and consequently, they are rarely integrated into commercial agricultural practices. In the current study, we applied metabolic-based community-modeling approaches for promoting realistic in terra solutions by simulation-based prioritization of alternative supplements as potential biostimulants, considering a collection of indigenous bacteria. Efficacy of biostimulants as enhancers of the indigenous degrader Paenarthrobacter was ranked through simulation and validated in pot experiments. A two-dimensional simulation matrix predicting the effect of different biostimulants on additional potential indigenous degraders (Pseudomonas, Clostridium, and Geobacter) was crossed with experimental observations. The overall ability of the models to predict the compounds that act as taxa-selective stimulants indicates that computational algorithms can guide the manipulation of the soil microbiome in situ and provides an additional step toward the educated design of biostimulation strategies. IMPORTANCE Providing the food requirements of a growing population comes at the cost of intensive use of agrochemicals, including pesticides. Native microbial soil communities are considered key players in the degradation of such exogenous substances. Manipulating microbial activity toward an optimized outcome in efficient biodegradation processes conveys a promise of maintaining intensive yet sustainable agriculture. Efficient strategies for harnessing the native microbiome require the development of approaches for processing big genomic data. Here, we pursued metabolic modeling for promoting realistic in terra solutions by simulation-based prioritization of alternative supplements as potential biostimulants, considering a collection of indigenous bacteria. Our genomic-based predictions point at strategies for optimizing biodegradation by the native community. Developing a systematic, data-guided understanding of metabolite-driven targeted enhancement of selected microorganisms lays the foundation for the design of ecologically sound methods for optimizing microbiome functioning.

Strategies for Enhancing in vitro Degradation of Linuron by Variovorax sp. Strain SRS 16 Under the Guidance of Metabolic Modeling.

Phenyl urea herbicides are being extensively used for weed control in both agricultural and non-agricultural applications. Linuron is one of the key herbicides in this family and is in wide use. Like other phenyl urea herbicides, it is known to have toxic effects as a result of its persistence in the environment. The natural removal of linuron from the environment is mainly carried through microbial biodegradation. Some microorganisms have been reported to mineralize linuron completely and utilize it as a carbon and nitrogen source. Variovorax sp. strain SRS 16 is one of the known efficient degraders with a recently sequenced genome. The genomic data provide an opportunity to use a genome-scale model for improving biodegradation. The aim of our study is the construction of a genome-scale metabolic model following automatic and manual protocols and its application for improving its metabolic potential through iterative simulations. Applying flux balance analysis (FBA), growth and degradation performances of SRS 16 in different media considering the influence of selected supplements (potential carbon and nitrogen sources) were simulated. Outcomes are predictions for the suitable media modification, allowing faster degradation of linuron by SRS 16. Seven metabolites were selected for in vitro validation of the predictions through laboratory experiments confirming the degradation-promoting effect of specific amino acids (glutamine and asparagine) on linuron degradation and SRS 16 growth. Overall, simulations are shown to be efficient in predicting the degradation potential of SRS 16 in the presence of specific supplements. The generated information contributes to the understanding of the biochemistry of linuron degradation and can be further utilized for the development of new cleanup solutions without any genetic manipulation.

Microbial Ecology from the Himalayan Cryosphere Perspective.

Cold-adapted microorganisms represent a large fraction of biomass on Earth because of the dominance of low-temperature environments. Extreme cold environments are mainly dependent on microbial activities because this climate restricts higher plants and animals. Himalaya is one of the most important cold environments on Earth as it shares climatic similarities with the polar regions. It includes a wide range of ecosystems, from temperate to extreme cold, distributed along the higher altitudes. These regions are characterized as stressful environments because of the heavy exposure to harmful rays, scarcity of nutrition, and freezing conditions. The microorganisms that colonize these regions are recognized as cold-tolerant (psychrotolerants) or/and cold-loving (psychrophiles) microorganisms. These microorganisms possess several structural and functional adaptations in order to perform normal life processes under the stressful low-temperature environments. Their biological activities maintain the nutrient flux in the environment and contribute to the global biogeochemical cycles. Limited culture-dependent and culture-independent studies have revealed their diversity in community structure and functional potential. Apart from the ecological importance, these microorganisms have been recognized as source of cold-active enzymes and novel bioactive compounds of industrial and biotechnological importance. Being an important part of the cryosphere, Himalaya needs to be explored at different dimensions related to the life of the inhabiting extremophiles. The present review discusses the distinct facts associated with microbial ecology from the Himalayan cryosphere perspective.

Wide pH range tolerance in extremophiles: towards understanding an important phenomenon for future biotechnology.

Microorganisms that inhabit the extreme pH environments are classified as acidophiles and alkaliphiles. A number of studies emerged from extreme high (hot springs, hydrothermal vents) as well as low temperature (arctic and antarctic regions, sea water, ice shelf, marine sediments, cold deserts, glaciers, temperate forests, and plantations) environments have highlighted the occurrence of microorganisms (thermophiles/psychrophiles) with the ability to tolerate wide pH range, from acidic to alkaline (1.5-14.0 in some cases), under laboratory conditions. However, the sampling source (soil/sediment) of these microorganisms showed the pH to be neutral or slightly acidic/alkaline. The aim of the present review is to discuss the phenomenon of wide pH range tolerance possessed by these microorganisms as a hidden character in perspective of their habitats, possible mechanisms, phylogeny, ecological and biotechnological relevance, and future perspectives. It is believed that the genome is a probable reservoir of the hidden variations. The extremophiles have the ability to adapt against the environmental change that is probably through the expression/regulation of the specific genes that were already present in the genome. The phenomenon is likely to have broad implications in biotechnology, including both environmental (such as bioremediation, biodegradation, and biocontrol), and industrial applications (as a source of novel extremozymes and many other useful bioactive compounds with wide pH range tolerance).

A psychrotolerant strain of Serratia marcescens (MTCC 4822) produces laccase at wide temperature and pH range.

A psychrotolerant bacterial strain of Serratia marcescens, originally isolated from a glacial site in Indian Himalayan Region (IHR), has been investigated for laccase production under different culture conditions. The bacterial strain was found to grow between 4 to 45°C (opt. 25°C) and 3 to 14 pH (opt. 5 pH) on prescribed growth medium, coinciding with production of laccase in laccase producing medium. However, the production of laccase was more consistent toward alkaline pH. Laccase enzyme was partially purified using gel filtration chromatography. The molecular mass of laccase was determined ~53 kDa on native PAGE. The Km and Vmax values were determined to be 0.10 mM and 50.00 µM min(-1), respectively, with ABTS. Inoculum size (4.0% v/v at 1.5 O.D.) resulted in significantly higher production of laccase. Carbon and nitrogen sources also affected the laccase production significantly. All the carbon sources enhanced laccase production, xylose being the best enhancer (P < 0.01). Among nitrogen sources, organic sources were found to act as inhibitors (P < 0.01), and among the in-organic sources only sodium nitrate enhanced the laccase production. Low molecular weight organic solvents significantly (P < 0.01) enhanced laccase production up to 24 h of incubation with a decline in later incubation period. Production of laccase by the psychrotolerant bacterium in wide range of temperature and pH is likely to have inference in biotechnological processes.

Prolonged Laccase Production by a Cold and pH Tolerant Strain of Penicillium pinophilum (MCC 1049) Isolated from a Low Temperature Environment.

Production of laccase by a cold and pH tolerant strain of Penicillium pinophilum has been investigated under different cultural conditions for up to 35 days of incubation. The fungus was originally isolated from a low temperature environment under mountain ecosystem of Indian Himalaya. The estimations were conducted at 3 temperatures (15, 25, and 35°C), a range of pH (3.5-11.5), and in presence of supplements including carbon and nitrogen sources, vitamins, and antibiotics. Optimum production of laccase was recorded at 25°C (optimum temperature for fungal growth) and 7.5 pH. The production of enzyme was recorded maximum on day 28 (11.6 ± 0.52 U/L) following a slow decline at day 35 of incubation (10.6 ± 0.80 U/L). Fructose and potassium nitrate (0.2%) among nutritional supplements, chloramphenicol (0.1%) among antibiotics, and folic acid (0.1%) among vitamins were found to be the best enhancers for production of laccase. Relatively lower but consistent production of laccase for a longer period is likely to be an ecologically important phenomenon under low temperature environment. Further, enhancement in production of enzyme using various supplements will be useful for its use in specific biotechnological applications.

Cold, pH and salt tolerant Penicillium spp. inhabit the high altitude soils in Himalaya, India.

Twenty five fungal cultures (Penicillium spp.), isolated from soil samples from the high altitudes in the Indian Himalayan region, have been characterized following polyphasic approach. Colony morphology performed on five different media gave varying results; potato dextrose agar being the best for the vegetative growth and sporulation as well. Microscopic observations revealed 18 isolates to be biverticillate and 7 monoverticillate. Based on the phenotypic characters (colony morphology and microscopy), all the isolates were designated to the genus Penicillium. Exposure to low temperature resulted in enhanced sporulation in 23 isolates, while it ceased in case of two. The fungal isolates produced watery exudates in varying amount that in many cases increased at low temperature. All the isolates could grow between 4 and 37 °C, (optimum 24 °C), hence considered psychrotolerant. While all the isolates could tolerate pH from 2 to 14 (optimum 5-9), 7 isolates tolerated pH 1.5 as well. While all the fungal isolates tolerated salt concentration above 10 %; 10 isolates showed tolerance above 20 %. Based on ITS region (ITS1-5.8S-ITS2) analysis the fungal isolates belonged to 25 different species of Penicillium (showing similarity between 95 and 100 %). Characters like tolerance for low temperature, wide range of pH, and high salt concentration, and enhancement in sporulation and production of secondary metabolites such as watery exudates at low temperature can be attributed to the ecological resilience possessed by these fungi for survival under low temperature environment of mountain ecosystem.

Laccase Production from a Temperature and pH Tolerant Fungal Strain of Trametes hirsuta (MTCC 11397).

Laccase production by a temperature and pH tolerant fungal strain (GBPI-CDF-03) isolated from a glacial site in Indian Himalayan Region (IHR) has been investigated. The fungus developed white cottony mass on potato dextrose agar and revealed thread-like mycelium under microscope. ITS region analysis of fungus showed its 100% similarity with Trametes hirsuta. The fungus tolerated temperature from 4 to 48°C ± 2 (25°C opt.) and pH 3-13 (5-7 opt.). Molecular weight of laccase was determined approximately 45 kDa by native PAGE. Amplification of laccase gene fragment (corresponding to the copper-binding conserved domain) contained 200 bp. The optimum pH for laccase production, at optimum growth temperature, was determined between 5.5 and 7.5. In optimization experiments, fructose and ammonium sulfate were found to be the best carbon and nitrogen sources, respectively, for enhancing the laccase production. Production of laccase was favored by high carbon/nitrogen ratio. Addition of CuSO4 (up to 1.0 mM) induced laccase production up to 2-fold, in case of 0.4 mM concentration. Addition of organic solvents also induced the production of laccase; acetone showed the highest (2-fold) induction. The study has implications in bioprospecting of ecologically resilient microbial strains.