- 11200 SW 8th ST
Florida International University
Miami, FL 33199 - 7863821777
Krish Jayachandran
Florida International University, Earth and environement, Faculty Member
- Dr. Krish Jayachandran is a Distinguished University Professor of environmental microbiology/soil science in the Depa... moreDr. Krish Jayachandran is a Distinguished University Professor of environmental microbiology/soil science in the Department of Earth and Environment. Using microbiology as a central tool, he is specialized in nutrient cycling and soil health, microbial diversity and activity, isolation and characterization of pesticide degrading microorganisms, biocontrol of invasive plant species, marine and freshwater toxins and microbial degradation, and soil-plant-microbial interactions. His research projects have been funded by the ENP, SFWMD, USDA, NIEH, DOE, Silver Consortium, and World Bank/FAO. He has more than 300 publications, including referred articles, research reports, book chapters, conference publications, and over 50 invited lectures. Dr. Jayachandran co-founded the ongoing FIU Agroecology Program, which he built with the support of USDA grants of more than 15.0 million dollars towards research, education, student training, and outreach activities. Dr. Jayachandran has supervised directed research projects for >300 undergraduate students, graduated 50 master’s students, 15 PhD students, and served on several doctoral and master’s students committees. In his professional field, Dr. Jayachandran served as an Associate Editor for one of the premier environmental journals, Journal of Environmental Quality (2002-07), several journal’s Editorial Board, and Associate Editor for NACTA journal. He also served on ~35 research panels (as panel member and panel manager) that included EPA, NSF, USDA agencies. Dr. Jayachandran received several awards for his teaching, research, mentorship, service, community engagement from FIU and Fellow of American Society of Agronomy. This year, Dr. Jayachandran is promoted to Distinguished University Professor, and a recognition from his alma mater as TNAU Distinguished Alumnus Award.edit
Research Interests: Environmental Science, Mangrove, Wetland, Habitat, Ecosystem, and 4 moreIntertidal Zone, CRC, Storm surge, and Ecotone
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Anionic polyacrylamide (PAM) is a linear, water-soluble anionic polymer that is widely used for erosion control and water quality protection. There has been an issue whether this formulation could possibly have negative effects on soil... more
Anionic polyacrylamide (PAM) is a linear, water-soluble anionic polymer that is widely used for erosion control and water quality protection. There has been an issue whether this formulation could possibly have negative effects on soil microbial diversity by altering microbial binding to soil particles or to one another and thus restricting their mobility and role in carbon and nutrient cycling. We conducted an 8-year study annually applying ultra-high rates of PAM to soil and then monitored impacts on soil bacterial diversity. In July and August, we measured active soil bacterial and fungal biomass and microbial diversity in soils receiving 0 (control), 2,691, and 5,382 kg active ingredient PAM ha−1. Active microbial biomass in soil was 19–33 % greater in the untreated control than soil treated with 2,691 or 5,382 kg of active ingredient PAM ha−1. Active bacterial biomass in soil was 21–31 % greater in the control treatment than in soil treated with 2,691 or 5,382 kg of active ingredient PAM ha−1 in August, but not July. Active fungal biomass in soils was 38–50 % greater in the control treatment than soil treated with 2,691 or 5,382 kg of active ingredient PAM ha−1 in July, but not August. Molecular methods were used to access the bacterial diversity, richness, and evenness in an agricultural soil that received 0 (control), 2,691, and 5,382 kg of active ingredient PAM ha−1. We found that although soil receiving these massive PAM application rates and prolonged exposure may reduce active bacterial and fungal biomass, PAM application did not substantially or consistently affect bacterial structural diversity, richness, or evenness in this agricultural soil.
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Coastal wetlands occupy the intertidal zone between the freshwater Everglades and the Gulf of Mexico. At the interface with the marine environment, these wetlands are dominated by mangrove forests, tidal creeks, and mudfl ats. Behind the... more
Coastal wetlands occupy the intertidal zone between the freshwater Everglades and the Gulf of Mexico. At the interface with the marine environment, these wetlands are dominated by mangrove forests, tidal creeks, and mudfl ats. Behind the coastal fringe zone is an ecotone that transitions into a freshwater/upland community characterized by an increasing diversity of halophytic to glycophytic trees, shrubs, and herbaceous vegetation. These productive coastal wetlands provide numerous, important ecosystem services. Directly benefi ting humans, coastal wetlands function as habitat and nursery ground for shellfi sh and other commercially important fi sheries, stabilize the coastline, and lessen the impact of storm surges (Aburto-Oropeza et al. 2008; Costanza et al. 2008; Gedan et al. 2011). Moreover, some of the most important functions of coastal
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Research Interests: Entomology, Earth Sciences, Environmental Science, Chemistry, Groundwater, and 15 moreAgriculture, Environmental Chemistry, Biological Sciences, Environmental Sciences, Solid Phase Extraction, Ground Water, Environmental quality, Time Dependent, SUBSURFACE DRAINAGE, Lysimeter, Residence Time, Environment Quality, Atrazine, Environmental, and Growing Season
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Research Interests: Chemistry, Bioremediation, Medicine, Nuclear Chemistry, Multidisciplinary, and 15 moreAdsorption, Bacteria, Chromium, Reduction, Pyrolusite, Pollutant, Hexavalent Chromium, Oxides, Manganese Compounds, Energy Source, Silicon Dioxide, Soil Pollutants, Shewanella, Redox Reactions, and Shewanella oneidensis MR-1
We conducted kinetic batch experiments to determine the reduction of Chromium(VI) by a type strain of Shewanella alga (BrY-MT) ATCC 55627. Chromium(VI) was reduced to Chromium(III) by BrY-MT grown in three different substrates: BHIB... more
We conducted kinetic batch experiments to determine the reduction of Chromium(VI) by a type strain of Shewanella alga (BrY-MT) ATCC 55627. Chromium(VI) was reduced to Chromium(III) by BrY-MT grown in three different substrates: BHIB (brain heart infusion broth), TSB (tryptic soy broth), and M9 (minimum broth). Four different Cr(VI) concentrations 4.836, 10.00, 37.125, and 260.00 mg l-1 were reduced at different rates by BrY-MT in both aerobic and anaerobic conditions. BrY-MT grown in BHIB reduced the maximum amount of Cr(VI) followed by TSB and M9. Carbondioxide produced from bacterial respiration varied with and without Cr(VI) under both aerobic and anaerobic conditions. The Cr(VI) reduction data under anaerobic condition was fitted by a monod model to determine the bacterial kinetic parameters. The kinetic parameters determined by fitting the anaerobic experimental data were used to run a forward simulation for experiments conducted under aerobic conditions. The monod model was modified to account for an inhibition parameter for the Cr(VI) experiment at 260 mg l-1. All the parameters varied within a narrow range, and were distinct for different substrates. Our studies show that, successful in situ bioremediation of Cr(VI) is depended on the type of substrates (electron donors) and the concentration of Cr(VI) in geologic medium.
Research Interests: Chemistry, Speciation, Carbon Dioxide, Kinetics, Bioremediation, and 15 moreEnvironmental Pollution, Medicine, Multidisciplinary, Soil Pollution, Animals, Ground Water, Bacteria, Chromium, Anaerobic Exercise, Biotransformation, Decontamination, Experimental Data, Kinetic Parameter, Oxygen Consumption, and Shewanella
Fungal endophytes are the most ubiquitous and highly diverse microorganisms that inhabit the interior of healthy plants. They are important in plant ecology and offer untapped potential to improve plant health and productivity in... more
Fungal endophytes are the most ubiquitous and highly diverse microorganisms that inhabit the interior of healthy plants. They are important in plant ecology and offer untapped potential to improve plant health and productivity in agroecosystems. The endophytic assemblage of avocado is poorly understood; therefore, surveys of fungal endophytes of Persea americana Mill. (Avocado) in South Florida organic and conventional orchards were conducted. A total of 17 endophytic fungal species were recovered from healthy avocado terminal branches. Endophytic fungal species were identified by rDNA sequencing of the internal transcribed spacer (ITS) region, using UNITE Species Hypotheses to reliably assign a taxon name, and determined as belonging to the genera Alternaria, Cladosporium, Colletotrichum, Corynespora, Diaporthe, Lasiodiplodia, Neofusicoccum, Neopestalotiopsis, Phyllosticta, and Strelitziana. Endophyte community assemblage differed between organic and conventional agroecosystems. This is the first report of Alternaria eichhorniae, Cladosporium tenuissimum, Corynespora cassiicola, Colletotrichum alatae, Diaporthe fraxini-angustifoliae, Lasiodiplodia gonubiensis, Neofusicoccum algeriense, Neofusicoccum andinum, Neopestalotiopsis foedans, Phyllosticta capitalensis, and Strelitziana africana as endophytes of avocado. Evaluation using pathogenicity tests on avocado leaves and terminal branches showed that endophytic fungal isolates did not cause disease symptoms.
Research Interests: Botany, Microbiology, Biology, Colletotrichum, Microbiome, and 4 moreEndophyte, Phoma, Alternaria, and Cladosporium
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The roots of 27 species of South Florida plants in 15 families (including one cycad, six palms, one Smilax, and 19 dicotyledons) native to pine rockland and tropical hardwood hammock communities were examined for arbuscular mycorrhizal... more
The roots of 27 species of South Florida plants in 15 families (including one cycad, six palms, one Smilax, and 19 dicotyledons) native to pine rockland and tropical hardwood hammock communities were examined for arbuscular mycorrhizal fungi (AMF). These plants grow in the biologically diverse but endangered Greater Everglades habitat. Roots from field-grown and potted plants were cleared and stained. All 27 species had AMF and include 14 species having an endangered or threatened status. The Paris-type colonization occurred in two species in the families Annonaceae and Smilacaceae. The Arum-type occurred in 22 species in the families Anacardiaceae, Arecaceae (Palmae), Boraginaceae, Cactaceae (questionable), Euphorbiaceae, Fabaceae, Lauraceae, Melastomataceae, Polygalaceae, Rubiaceae, Simaroubaceae, Ulmaceae, and Zamiaceae. Three species in the families Fabaceae, Lauraceae, and Simaroubaceae had a mix of Paris- and Arum-types. The results have implications for the restoration of these endangered plant communities in the Everglades.
Research Interests: Botany, Microbiology, Biology, Fungi, Biodiversity, and 15 moreEndangered Species, Medicine, Colonization, Lauraceae, Biological Diversity, Colonisation, Habitat, Arbuscular mycorrhizal fungi, Florida, Mycorrhiza, Melastomataceae, Native Plants, Mycorrhizae, Arbuscular Mycorrhiza Fungi, and Arbuscular mycorrhiza
To determine whether chelation of Fe in slightly acidic soils will release sufficient P from Fe phosphate complexes to stimulate plant growth in P‐limited soils, the effect of EDDHA {ethylenediamine [di(o‐hydroxy‐phenylacetic) acid]}, a... more
To determine whether chelation of Fe in slightly acidic soils will release sufficient P from Fe phosphate complexes to stimulate plant growth in P‐limited soils, the effect of EDDHA {ethylenediamine [di(o‐hydroxy‐phenylacetic) acid]}, a strong synthetic Fe‐chelating compound, on plant growth was studied in two P‐deficient native prairie soils and a P‐rich agricultural soil. Under laboratory conditions, EDDHA increased P extractability in the three soils. Subsequently, in a prairie soil/water slurry, repeated application of 10−4 M EDDHA significantly increased big bluestem (Andropogon gerardii Vitman) growth and P uptake as compared with distilled water controls or slurries which received only a single application of 10−3 M EDDHA. In slurries prepared with agricultural soil, growth of big bluestem was not affected by either concentration of the EDDHA. When the effect of EDDHA on growth of mycorrhizal and nonmycorrhizal plants was compared, in the prairie soils without EDDHA, mycorrhizal plants were significantly larger than nonmycorrhizal plants. Mycorrhizal plants in EDDHA‐amended soil had significantly greater growth and P uptake than mycorrhizal plants in unamended soil. However, neither concentration of EDDHA affected growth of nonmycorrhizal plants. In agricultural soil, plant growth was not affected by the mycorrhizal fungus or the EDDHA amendment. It appears that siderophore production by mycorrhizae or other soil microbes can significantly increase P availability in low pH soils and that this is a feasible mechanism by which mycorrhizal plants could assess P sources unavailable to nonmycorrhizal plants.
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Vesicular-arbuscular mycorrhizal (VAM) fungi increase root uptake of P and other minerals, but their role in the uptake of herbicides has received far less attention. These experiments were conducted to determine the effect of the VAM... more
Vesicular-arbuscular mycorrhizal (VAM) fungi increase root uptake of P and other minerals, but their role in the uptake of herbicides has received far less attention. These experiments were conducted to determine the effect of the VAM fungus, Glomus epigaeus (Daniels and Trappe), on the absorption of atrazine and trifluralin by roots of corn and soybean. Atrazine uptake by excised corn-root
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Quantification of P‐mineralization rate in soil using isotopic dilution requires that soluble inorganic 32P (32Pi) be determined without interference from soluble organic 32P (32Po). Therefore, a method is needed to partition 32Pi and... more
Quantification of P‐mineralization rate in soil using isotopic dilution requires that soluble inorganic 32P (32Pi) be determined without interference from soluble organic 32P (32Po). Therefore, a method is needed to partition 32Pi and 32Po into physically separate solutions before radiation counting. A previously suggested method of extracting Pi into isobutanol with acidified molybdate was tested for efficiency of separation from Po. Inorganic P as KH2PO4 was completely recovered in the isobutanol phase with acid molybdate. Organic P (glycerophosphate) remained in the aqueous phase during the extraction. No Po hydrolysis was observed when sodium phytate, glycerophosphate, ribonucleic acid, adenosine 2′‐ and 3′‐monophosphate, and cytidine 2′‐ and 3′‐monophosphate were extracted, but detectable amounts of adenosine 5′‐triphosphate hydrolyzed. This technique was tested on four Kansas soils, and the levels of inorganic and organic P obtained by this method were the same as those detected by conventional analyses.
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Research Interests: Microbiology, Biology, Cyanobacteria, Microbial consortia, Medicine, and 15 moreBiodegradation, Phosphorus, Phylogeny, Bacterial Toxins, Florida, High Performance Liquid Chromatography, Microcystins, High Pressure Liquid Chromatography, Actinomycetales, Fresh water, Microcystin, Microcystis, Base Sequence, Molecular Sequence Data, and Microbacterium
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Microorganisms associated with medicinal plants are of great interest as they are the producers of important bioactive compounds effective against common and drug-resistant pathogens. The characterization and biodiversity of fungal... more
Microorganisms associated with medicinal plants are of great interest as they are the producers of important bioactive compounds effective against common and drug-resistant pathogens. The characterization and biodiversity of fungal endophytes of the Petiveria alliacea plant and their antimicrobial production potential are of great interest as they are known for their antimicrobial and anticancer properties. In this study, we investigated the endophytic fungal microbiome associated with P. alliacea, and the endophytic fungal isolates were classified into 30 morphotypes based on their cultural and morphological characteristics. Ethyl acetate extract of fungal endophytes was obtained by liquid–liquid partitioning of culture broth followed by evaporation. The crude extract dissolved in dimethyl sulfoxide was screened for antimicrobial activity against three bacterial strains (Escherichia coli ATTC 25902, Staphylococcus aureus ATTC 14775, Bacillus subtilis NRRL 5109) and two fungal strai...
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Huanglongbing (HLB), also known as citrus greening, is an insidious disease in citrus and has become a threat to the sustainability of the citrus industry worldwide. In the U.S., Candidatus Liberibacter asiaticus (CLas) is the pathogen... more
Huanglongbing (HLB), also known as citrus greening, is an insidious disease in citrus and has become a threat to the sustainability of the citrus industry worldwide. In the U.S., Candidatus Liberibacter asiaticus (CLas) is the pathogen that is associated with HLB, an unculturable, phloem-limited bacteria, vectored by the Asian Citrus Psyllid (ACP, Diaphorina citri). There is no known cure nor treatment to effectively control HLB, and current control methods are primarily based on the use of insecticides and antibiotics, where effectiveness is limited and may have negative impacts on beneficial and non-target organisms. Thus, there is an urgent need for the development of effective and sustainable treatment options to reduce or eliminate CLas from infected trees. In the present study, we screened citrus-derived endophytes, their cell-free culture supernatants (CFCS), and crude plant extracts for antimicrobial activity against two culturable surrogates of CLas, Sinorhizobium meliloti ...
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The use of weeds as insectary plants is an emerging management tactic by agroecologists to sustain beneficial insect species. Fallow lands have always been used by insects, and are an important part of their diet in fragmented ecosystems.... more
The use of weeds as insectary plants is an emerging management tactic by agroecologists to sustain beneficial insect species. Fallow lands have always been used by insects, and are an important part of their diet in fragmented ecosystems. Weeds provide nectar and floral resources to beneficial insects, and provide resources to keep those insects within a field in between flowering events. Using weeds as a tool in agricultural production reliant on pollination allows farmers to increase yield, end herbicide use, and increase biodiversity of both plants and insects. Native weeds expand the range of native insects from natural areas into agroecosystems, supporting insects that buffer against lapses in pollination by agricultural honey bees. Weeds also support parasitoid and predatory insects by providing nectar and pollen to adults, as well as alternative prey. This review examines the plant-insect ecological interactions supported by weeds left within a farm, and their potential role ...
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Proximate interpretation of soil properties is essential for sustainable agriculture, demonstrating this for a possum trot farm located in South Florida, Miami Dade County (MDC), known for diverse agronomic regions over the decade. In... more
Proximate interpretation of soil properties is essential for sustainable agriculture, demonstrating this for a possum trot farm located in South Florida, Miami Dade County (MDC), known for diverse agronomic regions over the decade. In this work, we explore the capabilities of multispectral images (Sentinel 2A and Landsat 8) for accessing the dynamic soil properties of the study site. The predefined combinations of spectral band values (spectral indices) of Sentinel 2A and Landsat 8 image on the study area were used for evaluation. The correlation coefficient and linear regression models were demonstrated to assess the relationship between the derived spectral indices and five topsoil properties (Bulk Density (BD), Soil Organic Matter (SOM), Electric Conductivity (EC), pH, and Water Content). The results illustrated that specific soil properties (SOM, EC, pH, and BD) correlated well with different spectral indices with both images. Eight spectral bands combinations were found good with three soil properties with maximum correlation coefficient (R = 0.623) for Sentinel 2A, and Landsat 8 has maximum correlation coefficient (R = 0.463) of three spectral indices for two soil properties. The influence of distinct spectral bands of multispectral satellite images in soil surface properties involved in the best-suited indices algorithms was discussed in this article. Overall, we found that the spectral indices demonstrated promising results for this study, and hence they can be accounted for in soil investigation in agriculture.
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Agricultural practices, specifically crop and land management schemes, greatly influence the ability of soil to produce CO2 under varying conditions. A 2-year research study was planned to quantify carbon-dioxide (CO2) emission fluxes and... more
Agricultural practices, specifically crop and land management schemes, greatly influence the ability of soil to produce CO2 under varying conditions. A 2-year research study was planned to quantify carbon-dioxide (CO2) emission fluxes and total C (TC) contribution in a no-till tropical soil under carambola with sunn hemp-velvet bean cover cropping (CC) systems. Composted poultry manure (PM) was applied as an additional N source. The treatments were fallow control (F), fallow with PM (FM), sunn hemp (SH), SH with PM (SHM), velvet bean (VB), and VB with PM (VBM). Average daily CO2 emission from VB was 23 and 15% higher than control and SH plots, respectively, during CC growing season. Similarly, CO2 emission after CC termination was highest from VB plots. About 17% higher CO2-C emission was observed from manure applied plots which indicates that additional food sources stimulated microbial activity in the soils and subsequently produced more CO2. However, total C contribution in SH pl...