Tropical Isolates Research Articles

Insights into the biodegradation of polyhydroxyalkanoates by the tropical marine isolate, Nocardiopsis dassonvillei NCIM 5124.

The online version contains supplementary material available at 10.1007/s13205-024-04079-3.

Comparative evaluation of temperate, subtropical, and tropical isolates of nucleopolyhedrovirus against tomato fruit borer, Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae)

BackgroundThe tomato fruit borer, Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae), is a serious insect pest owing to its polyphagous nature, migrating long distances, greater capacity to develop resistance against insecticides and persistence in cropping areas. The comparative evaluation of temperate, sub-tropical and tropical H. armigera NPV (HearNPV) isolates was carried out to determine the potential of local and exotic HearNPV isolates for the management of H. armigera in Kashmir, India, having a temperate climate.ResultsMortality of 2nd instar H. armigera larvae with three different HearNPV isolates at different concentrations ranged between 13.40 and 73.25%, with significant differences between the concentrations in each isolate under laboratory conditions. The median lethal concentration (LC50) values of HearNPV-IND-K, HearNPV-IND-J, and HearNPV-IND-B isolates against 2nd instar H. armigera larvae were 4.62 × 103, 5.99 × 104, and 7.24 × 104 OBs/larva at 10th day post inoculation, with significant differences among the isolates. In time response bioassays, the cumulative mortality (%) caused by median lethal concentration (LC50) of HearNPV-IND-K, HearNPV-IND-J and HearNPV-IND-B isolates over a period of 10 days was 50.33, 49.00 and 49.00%, respectively. Their median survival time (ST50) values against 2nd instar H. armigera larvae were 8.10, 8.94 and 9.50 days, respectively, with significant differences among the isolates. The results revealed that the LC50 and ST50 values of HearNPV-IND K isolate were significantly lower than HearNPV-IND-J and HearNPV-IND-B isolates. The cumulative mortality of H. armigera larvae with HearNPV-IND-K, HearNPV-IND-J and HearNPV-IND-B isolates at different concentrations ranged between 22.00–68.32, 20.54–55.17, 11.66–44.33%, respectively, on tomato crop under field conditions. The highest mortality rate of 68.32% was observed at the local isolate (HearNPV-IND-K).ConclusionsIt’s concluded that the local isolate had the potential for the development of species-specific and environmentally safe biocontrol agent for organic farming and its incorporation into Integrated Pest Management program may reduce the use of chemical insecticides in Kashmir.

Whole-Genome Sequencing of the Tropical Marine Bacterium Nocardiopsis dassonvillei NCIM 5124, Containing the Ectoine Biosynthesis Gene Cluster ectABC

ABSTRACTThe genome sequence (7,057,619 bp; GC content, 72.07%) of a tropical marine isolate, Nocardiopsis dassonvillei NCIM 5124, containing the biomedically and biotechnologically important gene cluster ectABC is reported here.

Decolorization of Synthetic Dyes by Tropical Fungi Isolated from Taman Eden 100, Toba Samosir, North Sumatra, Indonesia

Taman Eden 100 is one of the tourist parks located in Toba Samosir, North Sumatra, Indonesia that provides a wide range of biodiversity. The objective of this research was to obtain the potential fungal isolate with high laccase activity to decolorize synthetic dyes. The results show that six isolates of Perenniporia subtephropora EDN 050, Trametes hirsuta EDN 082, T. hirsuta EDN 084, T. hirsuta EDN 085, Deconica coprophila EDN 114, and T. pavonia EDN 134, which were confirmed by molecular identification using 5.8 rDNA/ITS analysis, exhibited decolorization activity. Six potential isolates showed the ability to decolorize textile dyes of Acid Blue 129, RBBR,Orange II, and Reactive Black 5. The highest decolorization rate of 100 ppm Acid Blue 129, RBBR, Orange II, and Reactive Black 5 dyes by using T. pavonia EDN 134 were 98.87%, 98.26%, 100%, and 98.11%, respectively after 96 h incubation. Almost all positive isolates also decolorized dyes at higher concentrations (1,000 ppm). This study offers the potential of Indonesian tropical fungal isolates for synthetic dyes waste treatment.

Degradation of polystyrene by tropical bacterial and fungal isolates

Plastic waste is one of the major contributing factors to the growth of municipal solid wastes globally. It is a threat to public health and negatively impact the aquatic and terrestrial animals due to its persistence in the environment. Bacterial and fungal isolates were tested for their ability to degrade polystyrene. The cultures were grown on mineral salts medium supplemented with polystyrene as the sole carbon source in 250 mL conical flasks. The polystyrene reduced from 1 g (week 0) to 0.7g (week 7). Statistical analysis of variance (one-way ANOVA) shows a significant difference between the reduction in weight of polystyrene in the experimental flask compared to the control (P<0.05). Gas chromatography mass spectrometry analysis of biodegradation products shows that some toxic polystyrene constituents such as O-xylene, cis-9-hexadecenal and 3-phenol pentadecyl were removed.

Tropical forest fragmentation and isolation: Is community decay a random process?

Habitat destruction and degradation are the leading causes of species declines and extinctions in the world. Human altered landscapes often leave fragments of previously continuous habitat, which may be of significant conservation value. We assessed the effects of habitat fragmentation on the taxonomic diversity, community composition, and nestedness of avian communities before and after fragment isolation at the Biological Dynamics of Forest Fragments Project research site in the Amazon rainforest. Species loss in 10ha and 100ha fragments was significantly different from random taxonomic loss. In addition, after fragment isolation, but not prior to fragmentation, the species in the 10ha fragments were a nested subset of the species in the 100ha fragments. Finally, within the fragments two distinct communities formed, those on the edge of the fragments and those at the interior of the fragments, indicating that edge species did not penetrate the interior portion of the fragments. The controlled isolation of fragments from continuous forest resulted in rapid changes in the taxonomic diversity and species composition where fragment size served as a driver of species assemblages across the landscape. We suggest that future research continue to assess community level adjustments to habitat fragmentation and investigate the drivers behind the non-random loss of taxonomic groups and the nested structure of species composition of smaller fragments into larger ones after habitat fragmentation.

Identification and molecular characterisation of fifteen tropical isolates of the entomopathogenic fungus Metarhizium

ABSTRACTTwelve Metarhizium isolates from Costa Rica, two from Honduras and one from Nicaragua were characterised using molecular and morphological information. Two gene sequences, TEF1-α and β-TUB, identified isolates as M. anisopliae, M. brunneum and M. robertsii, and has provided new sequence information. Eleven SSRs revealed fourteen different genotypes. Morphological variability coincided with allelic diversity within species. This work provides a starting point for the application of integral biocontrol programmes, but more comprehensive and detailed surveys are warranted to understand the species composition and genetic diversity of the Metarhizium in Central America.

Non Nucleoside Reverse Transcriptase Inhibitors, Molecular Docking Studies and Antitubercular Activity of Thiazolidin-4-one Derivatives.

Management of Co-existence of Acquired immunodeficiency syndrome and Tuberculosis has become a global challenge due to the emergence of resistant strains and pill burden. Hence the aim of the present work was to design and evaluate compounds for their dual activity on HIV-1 and Tuberculosis (TB). A series of seven, novel Thiazolidin-4-one derivatives were synthesized and evaluated for their anti-HIV and anti-tubercular activity along with Molecular docking studies. All the seven compounds displayed promising activity against the replication of HIV-1 in cell-based assays. The four most active compounds were further evaluated against X4 tropic HIV-1UG070 and R5 tropic HIV-1VB59 primary isolates. The binding affinity of all the designed compounds for HIV-RT and Mycobacterium tuberculosis Enol Reductase (MTB InhA) was gauged by molecular docking studies which revealed crucial thermodynamic interactions governing their binding. The CC50 values for the test compounds were in the range of, 15.08-34.9 μg/ml, while the IC50 values were in the range of 16.1-27.13(UG070; X4) and 12.03-23.64 (VB59; R5) μg/ml. The control drug Nevirapine (NVP) exhibited CC50 value of 77.13 μg/ml and IC50 value of 0.03 μg/ml. Amongst all these compounds, compound number 3 showed significant activity with a TI value of 2.167 and 2.678 against the HIV-1 X4 and the R5 tropic virus respectively. In anti-mycobacterial screening, the compounds proved effective in inhibiting the growth of both log phase and starved MTB cultures. Compound 3 has been found to be active against HIV-1 as well as MTB.

Evaluating the performance of freshwater macroalgae in the bioremediation of nutrient-enriched water in temperate environments

Algal bioremediation can significantly improve the quality of wastewater by assimilating nutrients. However, the efficiency and stability of this approach depends on identifying suitable algae based on their biomass productivity and ability to outcompete less desirable algae. Here, we compare the productivity and competitive ability of three taxa of filamentous macroalgae under the seasonal light and temperature conditions experienced in temperate environments, including extremes of heat and cold. Specific growth rate was greatest for the tropical isolate of Oedogonium under summer conditions (36–40%; P 90% for both) and, in its absence, Hyalotheca also dominate over Oedogonium. Our results suggest that rather than finding an optimal taxon for all four seasons, the best decision for maximising stable biomass production will require either seasonal rotation of algae, or bi-cultures of the most dominant ones. Further, prioritising competition over production when selecting freshwater algae for wastewater bioremediation is likely to prove the most successful strategy.

Human Interleukin-34 facilitates microglia-like cell differentiation and persistent HIV-1 infection in humanized mice

BackgroundMicroglia are the principal innate immune defense cells of the centeral nervous system (CNS) and the target of the human immunodeficiency virus type one (HIV-1). A complete understanding of human microglial biology and function requires the cell’s presence in a brain microenvironment. Lack of relevant animal models thus far has also precluded studies of HIV-1 infection. Productive viral infection in brain occurs only in human myeloid linage microglia and perivascular macrophages and requires cells present throughout the brain. Once infected, however, microglia become immune competent serving as sources of cellular neurotoxic factors leading to disrupted brain homeostasis and neurodegeneration.MethodsHerein, we created a humanized bone-marrow chimera producing human “microglia like” cells in NOD.Cg-PrkdcscidIl2rgtm1SugTg(CMV-IL34)1/Jic mice. Newborn mice were engrafted intrahepatically with umbilical cord blood derived CD34+ hematopoietic stem progenitor cells (HSPC). After 3 months of stable engraftment, animals were infected with HIV-1ADA, a myeloid-specific tropic viral isolate. Virologic, immune and brain immunohistology were performed on blood, peripheral lymphoid tissues, and brain.ResultsHuman interleukin-34 under the control of the cytomegalovirus promoter inserted in NSG mouse strain drove brain reconstitution of HSPC derived peripheral macrophages into microglial-like cells. These human cells expressed canonical human microglial cell markers that included CD14, CD68, CD163, CD11b, ITGB2, CX3CR1, CSFR1, TREM2 and P2RY12. Prior restriction to HIV-1 infection in the rodent brain rested on an inability to reconstitute human microglia. Thus, the natural emergence of these cells from ingressed peripheral macrophages to the brain could allow, for the first time, the study of a CNS viral reservoir. To this end we monitored HIV-1 infection in a rodent brain. Viral RNA and HIV-1p24 antigens were readily observed in infected brain tissues. Deep RNA sequencing of these infected mice and differential expression analysis revealed human-specific molecular signatures representative of antiviral and neuroinflammatory responses.ConclusionsThis humanized microglia mouse reflected human HIV-1 infection in its known principal reservoir and showed the development of disease-specific innate immune inflammatory and neurotoxic responses mirroring what can occur in an infected human brain.

Day length as a key factor moderating the response of coccolithophore growth to elevated pCO2

AbstractThe fate of coccolithophores in the future oceans remains uncertain, in part due to key factors having not been standardized across experiments. A potentially moderating role for differences in day length (photoperiod) remains largely unexplored. We therefore cultured four different geographical isolates of the species Emiliania huxleyi, as well as two additional species, Gephyrocapsa oceanica (tropical) and Coccolithus braarudii (temperate), to test for interactive effects of pCO2 with the light : dark (L : D) cycle. We confirmed a general regulatory effect of photoperiod on the pCO2 response, whereby growth and particulate inorganic carbon and particulate organic carbon (PIC : POC) ratios were reduced with elevated pCO2 under 14 : 10 h L : D, but these reductions were dampened under continuous (24 h) light. The dynamics underpinning this pattern generally differed for the temperate vs. tropical isolates. Reductions in PIC : POC with elevated pCO2 for tropical taxa were largely through reduced calcification and enhanced photosynthesis under 14 : 10 h L : D, with differences dampened under continuous light. In contrast, reduced PIC : POC for temperate strains reflected increases of photosynthesis that outpaced increases in calcification rates under 14 : 10 h L : D, with both responses again dampened under continuous light. A multivariate analysis of 35 past studies of E. huxleyi further demonstrated that differences in photoperiod account for as much as 40% (strain B11/92) to 55% (strain NZEH) of the variance in reported pCO2‐induced reductions to growth but not PIC : POC. Our study thus highlights a critical role for day length in moderating the effect of ocean acidification on coccolithophore growth and consequently how this response may play out across latitudes and seasons in future oceans.

Temperature-dependent germination, growth and co-infection of Beauveria spp. isolates from different climatic regions

ABSTRACTBiological control agents based on entomopathogenic fungi traditionally contain a single strain that is efficient under certain biotic and abiotic conditions. Since particularly abiotic conditions vary, biological control efficiency may become more resilient at extreme temperatures if two or more fungal strains are combined based on their adaptations to their original environment. Here we evaluated the in vitro temperature-dependent germination and growth rate for six Beauveria spp. isolates originating from either arctic or tropical regions. Isolates of arctic origin showed higher germination and growth rate at 8°C and 12°C than isolates from the tropics while the latter group showed highest germination and in vitro growth at 32°C. Three of the isolates belonging to Beauveria bassiana were further tested in vivo for temperature-dependent infection in the mealworm beetle Tenebrio molitor both individually and combined. The same amounts of conidia were used in all bioassays. Virulence was isolate dependent at all temperatures with no additional effect at the low (12°C) and high (32°C) temperatures of combinations of arctic and tropical isolates. The results therefore indicate that adaptations to abiotic conditions in the natural environment do not directly reflect the effect of biotic environment (such as host infection) under similar conditions. Selection of isolates for biocontrol agents should not be based solely on in vitro experiments, while isolate selection based on virulence should also include considerations of the abiotic conditions the isolates are expected to function.

Diversity of endemic rhizobia on Christmas Island: Implications for agriculture following phosphate mining

Given that phosphate supplies may diminish and become uneconomic to mine after 2020, there is a compelling need to develop alternative industries to support the population on Christmas Island. Former mine sites could be turned into productive agricultural land, however, large-scale commercial agriculture has never been attempted, and, given the uniqueness of the island, the diversity of rhizobia prior to introducing legumes needed evaluation. Therefore, 84 rhizobia isolates were obtained from nine different hosts, both crop and introduced legumes, located at seven sites across the island. Based on 16S rRNA and recA gene sequence analysis, the isolates grouped into 13 clades clustering within the genus Bradyrhizobium, Ensifer, Cupriavidus and Rhizobium. According to the sequences of their symbiosis genes nodC and nifH, the isolates were classified into 12 and 11 clades, respectively, and clustered closest to tropical or crop legume isolates. Moreover, the symbiosis gene phylogeny and Multi Locus Sequence Analysis gene phylogeny suggested vertical transmission in the Alpha-rhizobia but horizontal transmission within the Beta-rhizobia. Furthermore, this study provides evidence of a large diversity of endemic rhizobia associated with both crop and introduced legumes, and highlights the necessity of inoculation for common bean, chickpea and soybean on the Island.

Short-term deleterious effects of standard isolation and cultivation methods on new tropical freshwater microalgae strains.

Algae with potential biotechnological applications in different industries are commonly isolated from the environment in order to obtain pure (axenic) stocks that can be safely stored for long periods of time. To obtain axenic cultures, antibiotics are frequently employed, and cryopreservation is applied to preserve standing stocks. However, many of these now standard methods were developed using strains derived from pristine to near-pristine environments and cold to temperate regions. The potential effect of the said methods on the life cycle and biochemical profile of algae isolates from hyper-eutrophic and constant high-temperature tropical regions is not well understood. These effects could potentially render them unsuitable for their intended biotechnological application. In this study, we conducted a genetic characterization (18S rRNA) and evaluated the effect of purification (the use of the antibiotic chloramphenicol, CAP) and cryopreservation (dimethyl sulfoxide; DMSO–sucrose mix and glycerol) on the growth rate and lipid content of three new tropical freshwater algal isolates: Chorella sp. M2, Chlorella sp. M6, and Scenedesmus sp. R3, obtained from the Ecuadorian coast. The genetic and morphological characterization revealed a clear discrimination between these strains. All strains cultured with CAP exhibited a lower growth rate. Subsequent to cryopreservation, Chorella sp. M2, Chlorella sp. M6, and Scenedesmus sp. R3 presented no significant difference in growth rate between the cryopreservants. Further, a significantly higher lipid content was observed in the biomass cryopreserved with glycerol in relation to the DMSO–sucrose, with Chorella sp. M2 and Chlorella sp. M6 having twice as much as they had in the first treatment. These results highlight the relevance of selecting an appropriate method for storage, as the materials used can affect the biological performance of different tropical species, although it is still to be determined if the effects observed in this study are long lasting in subsequent cultures of these algae.

VARIATION IN AGGRESSIVENESS AND AFLP AMONG Alternaria solani ISOLATES FROM INDONESIA

<p><em>Alternaria solani </em>is a necrotroph fungus that causes three-phased diseases in tomato. Management of the pathogen by using resistant cultivars requires knowledge on the aggressiveness and genetic diversity of the fungus. The aims of this study were to isolate <em>A. solani </em>from major tomato and potato producing areas in Indonesia and to study their aggressiveness and genetic variability. Twenty two<strong> </strong><em>A. solani</em><strong> </strong>isolates were recovered from early blighted tomato and potato in Central and West Java.<strong> </strong><em>A. alternata</em><strong> </strong>was also isolated from tomato leaves in West Java and North Sumatra, indicating that early blight in Indonesia may be caused by more than one <em>Alternaria </em>species. Resistance tests of four tomato genotypes to selected<strong> </strong><em>A. solani</em><strong> </strong>isolates revealed that local isolates were more aggressive in inciting early blight and stem lesion than an imported isolate from USA. This implies that introduced breeding materials must be tested to local isolates to obtain effective resistance genes. Cluster analysis based on amplified fragment length polymorphism (AFLP) obtained from <em>Eco</em>RI+AG and<strong> </strong><em>Mse</em>I+C primer amplification separated 28 local and Taiwan isolates from the US isolate, which was coincided with aggressiveness separation between the local isolates and the US isolate. Three clusters of AFLP genotypes which did not associate with geographic origin were observed among tropical isolates. The low genetic diversity among the Indonesian isolates suggests clonal population structure with wide distribution. Successful local tomato breeding requires the availability of local<strong> </strong><em>A. solani </em>collection with well-characterized aggressiveness level and molecular diversity to obtain effective resistance genes.</p>

Effects of temperature on extracellular hydrolase enzymes from soil microfungi

Soil microbes play important roles in global carbon and nutrient cycling. Soil microfungi are generally amongst the most important contributors. They produce various extracellular hydrolase enzymes that break down the complex organic molecules in the soil into simpler form. In this study, we investigated patterns of amylase and cellulase (which are responsible for breaking down starch and cellulose, respectively) relative activity (RA) on solid media at different culture temperatures in fungal strains from Arctic, Antarctic and tropical soils. Fungal isolates from all three regions were inoculated onto R2A media supplemented with starch for amylase and carboxymethylcellulose and trypan blue for cellulase screening. The isolates were then incubated at 4, 10, 15, 20, 25, 30, 35 and 40 °C and examined for activity after 5 and 10 days, for tropical and polar isolates, respectively. The data obtained indicate that the polar fungal strains exhibited similar patterns of amylase and cellulase RA. Both Arctic and Antarctic fungi showed highest RA for amylase and cellulase at 35 °C, while colony growth was maximised at 15 °C. Colony growth and RA of the polar isolates were negatively correlated suggesting that, as temperatures increase, the cells become stressed and have fewer resources available to invest in growth. Unlike polar isolates, tropical isolates did not exhibit any trend of colony growth with temperature, rather having idiosyncratic patterns in each isolate. The low enzyme production and RA levels in the tropical strains may suggest both a low ability to respond to temperature variation in their natural thermally stable tropical habitats, as well as a level of thermal stress limiting their enzyme production ability.

Tropical soils are a reservoir for fluorescent Pseudomonas spp. biodiversity.

Fluorescent Pseudomonas spp. are widely studied for their beneficial activities to plants. To explore the genetic diversity of Pseudomonas spp. in tropical regions, we collected 76 isolates from a Brazilian soil. Genomes were sequenced and compared to known strains, mostly collected from temperate regions. Phylogenetic analyses classified the isolates in the P. fluorescens (57) and P. putida (19) groups. Among the isolates in the P. fluorescens group, most (37) were classified in the P. koreensis subgroup and two in the P. jessenii subgroup. The remaining 18 isolates fell into two phylogenetic subclades distinct from currently recognized P. fluorescens subgroups, and probably represent new subgroups. Consistent with their phylogenetic distance from described subgroups, the genome sequences of strains in these subclades are asyntenous to the genome sequences of members of their neighbour subgroups. The tropical isolates have several functional genes also present in known fluorescent Pseudomonas spp. strains. However, members of the new subclades share exclusive genes not detected in other subgroups, pointing to the potential for novel functions. Additionally, we identified 12 potential new species among the 76 isolates from the tropical soil. The unexplored diversity found in the tropical soil is possibly related to biogeographical patterns.

Within-species and temperature-related variation in the growth and natural products of the red alga Asparagopsis taxiformis

The red algal genus Asparagopsis (Bonnemaisoniaceae) is a significant resource for bioactive natural products. However, prior to domestication for commercial production, we need to understand the potential variation in growth and concentration of natural products between isolates of Asparagopsis and, beyond that, how these traits are affected by environmental conditions. Ten isolates of Asparagopsis taxiformis were collected from tropical and warm-temperate regions in Queensland, Australia, and identified by molecular barcoding of the mitochondrial intergenic spacer (cox2–3 spacer). The isolates were cultured at three temperatures ranging from the minimum of the warm-temperate region to the maximum of the tropical region. Growth rates and the concentration of natural products varied between the region of origin, between isolates within region and between temperatures. Growth differed by up to 50% between isolates, whereas the concentration of natural products differed more than tenfold. Growth rates were highest at the minimum temperature of 20.2°C, irrespective of region of origin, and were lowest at the maximum temperature of 28.1°C. Natural products were threefold higher in tropical isolates, and this variation was not correlated to growth. Consequently, targeting isolates with high concentrations of natural products should be the primary strategy for the domestication of Asparagopsis for biotechnology applications.

Fatty acid production of tropical thraustochytrids from Malaysian mangroves

Abstract A total of 33 tropical thraustochytrid isolates were isolated from fallen leaves of Malaysian mangroves. Phylogenetic analysis based on the 18S rRNA gene revealed that the majority of the 33 isolates belonged to the genus Aurantiochytrium, and only one isolate belonged to Parietichytrium. The specific growth rate and biomass productivity of the strains ranged from 0.17 to 0.93 day−1 and 0.03 to 0.62 g l−1 day−1, respectively. Lipid productivity ranged from 1.27 to 70.86 mg l−1 day−1. Fifteen fatty acids, dominated by C16:0 [19.5%–71.6% total fatty acid (TFA)], C15:0 (3.3%–43.1% TFA), C22:6n3 (1.5%–38.4% TFA) and C18:0 (2.9%–28.6% TFA), were identified. The total carotenoid content was shown to be a better chemotaxonomic character than fatty acid composition for the isolates. Aurantiochytrium sp. UMACC-T024 had the highest lipid productivity (70.86 mg l−1 day−1), and this was selected for an optimisation study. The optimal conditions for lipid production of Aurantiochytrium sp. UMACC-T024 were salinity 32, pH 7.5, 1% w/v glucose and 0.5 g l−1 yeast extract, which resulted in an enhanced lipid productivity of 263.37 mg l−1 day−1 at day 5.

Screening for Antagonistic Tropical Fungi against Selected Maize and Bean Pathogens

Phytopathogens are known to be the leading cause of important plant diseases which result in significant losses in agricultural crops. The need to maintain the level of yield both quantitatively and qualitatively is vital in order to curb the losses. So far there has been a positive advance recognized in research to the use of tropical fungi as biocontrol agents. The objective of this study was to screen for antagonistic tropical fungi against selected phytopathogens of maize (Zea mays L.) and beans (Phaseolus vulgaris L.) namely Fusarium graminearum, Fusarium moniliforme, Pythium ultimum, and Colletotrichum lindemuthianum in vitro. A total of 87 tropical fungi isolates were collected from Kakamega tropical rainforest, Kenya. Dual culture experiment was carried out to screen the tropical fungi against the selected phytopathogens. The bioassay was performed in a completely randomised design in triplicate and the inhibition zones recorded after every week for three weeks. Differential biocontrol ability among nine tropical fungi was noticed against F. moniliforme with the percentage inhibition increasing over time. Fusarium solani was the most active antagonist with an inhibition of 64% while Phaeomarasmius sp. had the lowest activity of 19.1% against F. moniliforme. Epicoccum sp. inhibited the mycelial growth of P. ultimum by 38% and also inhibited C. lindemuthianum by 58%. None of the fungal antagonists inhibited the mycelial growth of F. graminearum. The outcome of this study indicates that tropical fungi can be used as biocontrol agents and can be further explored and developed into effective fungicides for management of phytopathogens.