Production Of Extracellular Enzymes Research Articles

Isolation and characterization of plant growth promoting rhizobacteria (PGPR) from rhizosphere of Helianthus annuus L.

Plant growth-promoting rhizobacteria (PGPR) support plant growth through direct and indirect mechanisms. To investigate PGPR strains that support plant growth, 21 bacterial isolates, mostly Bacillus ssp. and Pseudomonas ssp., were isolated from different rhizospheric soils of sunflowers in Kırşehir districts in 2020. All isolates were characterized morphologically, biochemically by screening under in vitro conditions for plant growth-promoting properties such as nitrogen fixation, IAA (indoleacetic acid) production, siderophore production, HCN (hydrogen cyanide) production, inorganic phosphate solubility. It was also screened for extracellular enzyme production and antifungal activity against Fusarium oxysporum. Among the 21 isolates, 3 isolates (MH-35-4, MH-49-4, MH-64-3) fixed nitrogen, 2 isolates (MH-59-6, MH-64-3), produced siderophores, 8 isolates (MH-35-4, MH-35-6, MH-54-3, MH-54-4, MH-59-1, MH-59-2, MH-59-4, MH-59-8) produced HCN, 6 isolates (MH-35-6, MH-54-4, MH-59-1, MH-59-2, MH-59-4, MH-59-8) produced IAA, and 7 isolates (MH-35-4, MH-35-6, MH-59-1, MH-59-2, MH-59-4, MH-59-8, MH-64-3) solubilized inorganic phosphate. Additionally, only 2 isolates (MH-54-3, MH-54-4) were positive amylase tests, 8 isolates (MH-35-6, MH-54-4, MH-59-1, MH-59-2, MH-59-4, MH-59-6, MH-59-7, MH-59-8) were positive citrate tests, 8 isolates (MH-35-1, MH-35-4, MH-35-7, MH-49-4, MH-54-4, MH-59-6, MH-59-7, MH-64-3) were positive protease tests, and 6 isolates (MH-35-1, MH-35-3, MH-35-7, MH-54-3, MH-54-4, MH-59-7) were positive gelatin hydrolysis tests. Among 21 isolates, 38% were determined as hydrogen cyanide producers, 10% as siderophore producers, 29% IAA producers, 33% as phosphate solubilizers and 14% as nitrogen fixers. Isolate MH-35-6 showed the highest antifungal activity against Fusarium oxysporum with an inhibition rate of 53.57%. This was followed by isolates MH-54-1 (51.19%), MH-54-3 (47.61%) and MH-59-2 (38.09%), respectively. Therefore, our study reveals that bacteria that promote plant growth in sunflowers can be used to increase crop yield and as a biocontrol agent.

Microbial detoxification of chlorpyrifos, profenofos, monocrotophos, and dimethoate by a multifaceted rhizospheric Bacillus cereus strain PM38 and its potential for the growth promotion in cotton.

Bacillus genera, especially among rhizobacteria, are known for their ability to promote plant growth and their effectiveness in alleviating several stress conditions. This study aimed to utilize indigenous Bacillus cereus PM38 to degrade four organophosphate pesticides (OPs) such as chlorpyrifos (CP), profenofos (PF), monocrotophos (MCP), and dimethoate (DMT) to mitigate the adverse effects of these pesticides on cotton crop growth. Strain PM38 exhibited distinct characteristics that set it apart from other Bacillus species. These include the production of extracellular enzymes, hydrogen cyanide, exopolysaccharides, Indol-3-acetic acid (166.8μg/mL), siderophores (47.3μg/mL), 1-aminocyclopropane-1-carboxylate deaminase activity (32.4μg/mL), and phosphorus solubilization (162.9μg/mL), all observed at higher concentrations. This strain has also shown tolerance to salinity (1200mM), drought (20% PEG-6000), and copper and cadmium (1200mg/L). The amplification of multi-stress-responsive genes, such as acdS, ituC, czcD, nifH, sfp, and pqqE, further confirmed the plant growth regulation and abiotic stress tolerance capability in strain PM38. Following the high-performance liquid chromatography (HPLC) analysis, the results showed striking compatibility with the first kinetic model. Strain PM38 efficiently degraded CP (98.4%), PF (99.7%), MCP (100%), and DMT (95.5%) at a concentration of 300ppm over 48h at 35°C under optimum pH conditions, showing high coefficients of determination (R2) of 0.974, 0.967, 0.992, and 0.972, respectively. The Fourier transform infrared spectroscopy (FTIR) analysis and the presence of opd, mpd, and opdA genes in the strain PM38 further supported the potential to degrade OPs. In addition, inoculating cotton seedlings with PM38 improved root length under stressful conditions. Inoculation of strain PM38 reduces stress by minimizing proline, thiobarbituric acid-reactive compounds, and electrolyte leakage. The strain PM38 has the potential to be a good multi-stress-tolerant option for a biological pest control agent capable of improving global food security and managing contaminated sites.

A systematic review on products derived from nematophagous fungi in the biological control of parasitic helminths of animals.

Nematophagous fungi have been widely evaluated in the biological control of parasitic helminths in animals, both through their direct use and the use of their derived products. Fungal bioproducts can include extracellular enzymes, silver nanoparticles (AgNPs), as well as secondary metabolites. The aim of this study was to conduct a systematic review covering the evaluation of products derived from nematophagous fungi in the biological control of parasitic helminths in animals. In total, 33 studies met the inclusion criteria and were included in this review. The majority of the studies were conducted in Brazil (72.7%, 24/33), and bioproducts derived from the fungus Duddingtonia flagrans were the most commonly evaluated (36.3%, 12/33). The studies involved the production of extracellular enzymes (48.4%, 16/33), followed by crude enzymatic extract (27.2%, 9/33), secondary metabolites (15.1%, 5/33) and biosynthesis of AgNPs (9.1%, 3/33). The most researched extracellular enzymes were serine proteases (37.5%, 6/16), with efficacies ranging from 23.9 to 85%; proteases (31.2%, 5/16), with efficacies from 41.4 to 95.4%; proteases + chitinases (18.7%, 3/16), with efficacies from 20.5 to 43.4%; and chitinases (12.5%, 2/16), with efficacies ranging from 12 to 100%. In conclusion, extracellular enzymes are the most investigated derivatives of nematophagous fungi, with proteases being promising strategies in the biological control of animal helminths. Further studies under in vivo and field conditions are needed to explore the applicability of these bioproducts as tools for biological control.

Role of rhizospheric microbial enzymes in plant growth promotion, antagonism, and sustainable agriculture: A review

Plant growth-promoting rhizobacteria (PGPR) offer eco-friendly alternatives to chemical fertilizers, promoting sustainable agriculture by enhancing soil fertility, reducing pathogens, and aiding in stress resistance. In agriculture, they play a crucial role in plant growth promotion through the production of agroactive compounds and extracellular enzymes to promote plant health and protection against phytopathogens. In the rhizosphere, diverse microbial interactions, including those with bacteria and fungi, influence plant health by production of antimicrobial compounds. The antagonism displayed by rhizobacteria plays a crucial role in shaping microbial communities and has potential applications in developing a natural and environmentally friendly approach to pest control. The rhizospheric microbes showcase their ecological importance and potential for biotechnological applications in the context of plant-microbe interactions. The extracellular enzymes produced by rhizospheric microbes like amylases, chitinases, glucanases, cellulases, proteases, and ACC deaminase contribute to plant processes and stress response emphasizing their importance in sustainable agriculture. Moreover, this review highlights the new paradigm including artificial intelligence (AI) in sustainable horticulture and agriculture as a harmonious interaction between ecological networks for promoting soil health and microbial diversity that leads to a more robust and self-regulating agricultural system for protecting the environment in the future. Overall, this review emphasizes microbial interactions and the role of rhizospheric microbial extracellular enzymes which is crucial for developing eco-friendly approaches to enhance crop production and soil health.

Co-fermentation of acid treated coconut wastes using mixed Bacillus cultures for enhanced production of extracellular enzymes: Application in bioconversion of raw coconut fibers

Higher cost of production and functioning efficiency are the two most important aspects of cellulolytic enzymes, as they directly affect the bioconversion of cellulosic waste into fermentable sugars. Thus, the current study aims to investigate the production of cellulolytic enzymes from low-cost waste biomass for use in the sustainable hydrolysis of biomass to yield fermentable sugars. Since coconut waste is a major contributor to biodegradable waste, two different parts of coconut, including the hard shell of coconut (CS) and the fibers of the shell (FS), have been used for enzyme production as feedstock. Further, enzyme production has been carried out on co-fermentative and acid-pretreated coconut substrates (CS and FS) at different quantities using mixed bacterial cultures. Following this, a crude enzyme with a maximum 20 U/gds FPA, 62 U/gds BGL, and 167 U/gds EG has been produced by mixed Bacillus cultures under co-fermentation of 0.5 % acid-pretreated CS and FS substrates at a quantity of 5:5 (g:g) at 35 oC and pH 5.0. The crude enzyme showed its thermal stability for 16 h at 50 oC and released ∼34 g/L of sugars from the hydrolysis of untreated FS biomass in 24 h. This work may have significant applications in the area of biomass-based biorefining as well as waste management.

Bioprospecting of endophytic fungi from semidesert candelilla (Euphorbia antisyphilitica Zucc): Potential for extracellular enzyme production.

Endophytic microbial communities colonize plants growing under various abiotic stress conditions. Candelilla (Euphorbia antisyphilitica Zucc.) is a shrub that develops functionally in arid and semi-arid zones of Mexico; these conditions generate an association between the plant and the microorganisms, contributing to the production of enzymes as a defense mechanism for resistance to abiotic stress. The objective of this research was to isolate and identify endophyte fungi of candelilla and bioprospection of these endophytic fungi for enzyme production using candelilla by-products. Fungi were isolated and identified using ITS1/ITS4 sequencing. Their potency index (PI) was evaluated in producing endoglucanase, xylanase, amylase, and laccase. Fermentation was carried out at 30°C for 8 days at 200 rpm, with measurements every 2 days, using candelilla by-products as substrate. All fungi exhibited higher cellulase, amylase, and laccase activities on the 2nd, 6th, and 8th day of fermentation, respectively, of fermentation. The fungus Aspergillus niger ITD-IN4.1 showed the highest amylase activity (246.84 U/mg), the genus Neurospora showed the highest cellulase activity, reaching up to 13.45 FPU/mg, and the strain Neurospora sp. ITD-IN5.2 showed the highest laccase activity (3.46 U/mg). This work provides the first report on the endophytic diversity of E. antisyphilitica and its potential role in enzyme production.

Behaviours of methane metabolism and community dynamics of methane anaerobic oxidation microbes on carbonate rocks with long-term cultivation in cold seep environment

The anaerobic oxidation of methane (AOM) and sulfate reduction processes in cold seep environments can control methane emission sources and thus mitigate the pressure of increasing global greenhouse gas concentrations. The surfaces of carbonate rocks in cold seep host an abundance of microorganisms that participate in AOM reactions. Investigating the metabolism and conversion of methane by these microbes is instrumental in advancing the exploration and utilization of deep-sea methane energy. Previous studies primarily focused on in-situ investigations of microbial communities on carbonate rocks in cold seep environments, while the dynamic balance of carbonate mineralization caused by microbial community changes and the characteristics of methane consumption in carbonate samples remains unclear. In this study, we used methane as the sole carbon source, enriched and cultured carbonate samples under high pressure, and monitored the community dynamics regularly. The results demonstrated that methane consumption and metabolic pathways played a crucial role in influencing community succession and carbonate mineralization. AOM processes, coupled with sulfate reduction and nitrate reduction, which are dominated by ANME-2c, facilitate the precipitation of calcium carbonate. Conversely, the acetate production process, dominated by ANME-1, may hinder the efficiency of calcium carbonate mineralization. Additionally, the impact of bacterial groups in the enrichment process, through the production of extracellular enzymes, organic acid pathways, and the expression of carbonic anhydrase pathways on carbonate mineralization, should not be disregarded. These findings highlight the significance of diverse pathway methane metabolism in the dynamics of methane consumption, deep-sea microbial communities, carbonate kinetics, and marine biological carbon sequestration processes.

Generalizing Microbial Parameters in Soil Biogeochemical Models: Insights From a Multi‐Site Incubation Experiment

AbstractIncorporating microbial processes into soil biogeochemical models has received growing interest. However, determining the parameters that govern microbially driven biogeochemical processes typically requires case‐specific model calibration in various soil and ecosystem types. Here each case refers to an independent and individual experimental unit subjected to repeated measurements. Using the Microbial‐ENzyme Decomposition model, this study aimed to test whether a common set of microbially‐relevant parameters (i.e., generalized parameters) could be obtained across multiple cases based on a two‐year incubation experiment in which soil samples of four distinct soil series (i.e., Coland, Kesswick, Westmoreland, and Etowah) collected from forest and grassland were subjected to cellulose or no cellulose amendment. Results showed that a common set of parameters controlling microbial growth and maintenance as well as extracellular enzyme production and turnover could be generalized at the soil series level but not land cover type. This indicates that microbial model developments need to prioritize soil series type over plant functional types when implemented across various sites. This study also suggests that, in addition to heterotrophic respiration and microbial biomass data, extracellular enzyme data sets are needed to achieve reliable microbial‐relevant parameters for large‐scale soil model projections.

Cultivating a greener future: Exploiting trichoderma derived secondary metabolites for fusarium wilt management in peas

This study aimed to identify efficient Trichoderma isolate(s) for the management of Fusarium wilt in peas. Four different pea germplasms (Sarsabz, Pea-09, Meteor and Supreme) were evaluated for resistance against Fusarium oxysporum in pot assay. Resistant germplasm exhibits a varying range of disease severity (23%) and percent disease index (21%), whereas susceptible and highly susceptible germplasm exhibit maximum disease severity (44–79%) and percent disease index (47–82%). The susceptible germplasm Meteor was selected for in vivo experiment. Five different Trichoderma spp. (Trichoderma koningii, T. hamatum, T. longibrachiatum, T. viride, and T. harzianum) were screened for the production of hydrolytic extracellular enzymes under in vitro. In-vitro biocontrol potential of Trichoderma spp. was assayed by percentage inhibition of dry mass of Fusarium oxysporum pisi (FOP) with Trichoderma spp. metabolite filtrate concentrations. Maximum growth inhibition was observed by T. harzianum (50–89%). T. harzianum metabolites in filtrate conc. (40%, 50%, and 60%) exhibited maximum reduction in biomass and were thus used for in vivo management of the disease. The pot experiment for in-vivo management also confirmed the maximum inhibition of FOP by T. harzianum metabolites filtrate at 60% by reducing disease parameters and enhancing growth, yield, and physiochemical and stress markers. Trichoderma strains led to an increase in chlorophyll and carotenoids (34-26%), Total phenolic 55%, Total protein content 60%, Total Flavonoid content 36%, and the increasing order of enzyme activities were as follows: CAT > POX > PPO > PAL in all treatments. These strains demonstrate excellent bio-control of Fusarium wilt in pea via induction of defense-related enzymes. The present work will help use Trichoderma species in disease management programme as an effective biocontrol agent against plant pathogens.

Cultural and Morphological Characterization of Streptomyces and Interaction Study with Sclerotium rolfsii by SEM

Stem rot caused by Sclerotium rolfsii Sacc. is a major constraint in the production and productivity of the groundnut. Management of stem rot disease is very difficult due to soil borne nature, wide host range of S. rolfsii and lack of disease resistance in existing commercial cultivars. Biological control with potential Streptomyces is receiving greater attention all over the world. Studies were conducted on collection and isolation of Streptomyces, their mechanism of action, cultural and morphological characteristics, its efficacy against S. rolfsii with Scanning electron microscope(SEM). Roving survey was conducted in major groundnut growing regions of Andhra Pradesh. During survey 180 soil samples were collected from groundnut rhizosphere and 50 Streptomyces isolates were isolated from different soil samples. Twenty Streptomyces isolates were tested for their growth rate and antifungal activity against groundnut stem rot pathogen, S.rolfsii under in vitro conditions using dual culture method. Among twenty isolates of Streptomyces, five isolates showed maximum inhibition of S. rolfsii. These five isolates were characterized based on cultural and morphological characters. The study involved in differentiating various characters viz., type of spore chain, colony margins, shape of spore chains, colour of spore mass and spore surface. The morphology of the spore chains varied across the isolates showing the filamentous (Ggd), spiral (Kyd and Lrp) and Rectus flexibilis (Kdr and Mkc). SEM studies revealed that inhibition of the growth of S. rolfsii by Streptomyces was mainly due to exhibition of irregular distortions at contact site of the pathogen and collapse of the fungal hyphae and this might be due to the production of secondary metabolites and extracellular enzymes.

A STUDY ON EFFICIENT MICROORGANISMS ISOLATED FOR DEGRADATION FROM MUNICIPAL SOLID WASTE OF CHHATRAPATI SAMBHAJINAGAR, MAHARASHTRA, INDIA

With rapid industrial development and the progress of civilization, the problem of increased waste generation has become more complex in urban areas. This research evaluates the composition and characteristics of municipal solid Waste produced in a representative residential neighbourhood. Ten samples were taken from the disposal site of the Chhatrapati—Sambhajinagar (Aurangabad) city area. Gathered from garbage, nine bacterial isolates were made using a nutrient agar medium. Investigations were conducted into the best culture conditions, microbiological traits, biochemical traits within the strains, tolerance to five heavy metals (Cadmium, zinc, Arsenic, lead and mercury), sensitivity to four different antibiotics (penicillin, streptomycin, oxytetracycline, and gentamycin), and extracellular enzyme production of the microbial strains. All six strains that could produce protease were used for the waste degradation efficiency test. Due to these findings, there is now a greater chance of identifying bacteria of scientific significance from municipal waste disposal sites, and these isolates may be a key source of compounds with practical applications in industry. Based on the research, it is possible to extract beneficial bacteria for the environmentally friendly bioconversion of solid Waste from the (Chhatrapati. Sambhajinagar (Aurangabad) city area.

Adsorption–synergic biodegradation of aryl ethers model compounds constructed from lignite

The bioconversion of lignite under ambient conditions is a promising technology for coal processing. However, the bioconversion mechanism of lignite via microorganisms is unclear due to its complex structure. In this work, for the first time, four aryl ether model compounds (AEMCs) of lignite with three aromatic rings were selected based on the unique attack sites of fungi on lignite to explore the bioconversion performance. The results show that the biodegradation rates of 4,4′-(1,3-phenylenebis[oxy]) dianiline (4,4-1,3-POD), formononetin, 9,10-dibutoxyanthracene (9.10-DBO), and 6-methoxy-2-(4-methoxyphenyl) benzo [b] thiophene (6-M-2-B) reached 89.91%, 69.40%, 39.45%, and 83.44%, respectively. During the process, AEMCs serving as inducers increased the production of extracellular enzymes secreted by the WF8 fungus. Through analysis using ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR) and gas chromatography/mass spectroscopy (GC/MS), it was confirmed that new organic compounds (OCs) were generated after biodegradation of AEMCs, wherein the UV–Vis spectra of the four AEMCs after biodegradation were fitted by 5,5,9 and 8 sub-curves and the numbers of OCs identified in GC/MS spectra were 41, 48, 33 and 35, respectively. Predominantly, these new OCs contained carboxyl, hydroxyl or carbonyl groups, indicating the involvement of hydroxyl radicals and extracellular enzymes in the process. In addition, the adsorption of AEMCs onto the fungi was well-fitted with the Langmuir model, suggesting that the adsorption process was monolayer chemisorption. Finally, it was concluded that the adsorption–synergic biodegradation process can be divided into two stages: AEMCs were adsorbed by the fungi, stimulating the production and release of fungal enzymes, and were subsequently oxidatively attacked and degraded. This study provided a theoretical basis for well understanding the biodegradation of lignite.

Efficiency of bacterial isolates on suppressing brown spot in rice plants

AbstractMany fungicides can control brown spot, caused by Bipolaris oryzae in rice (Oryza sativa L.), although searching for beneficial microorganisms for biocontrol will improve sustainable integrated pest management. The aim of this investigation was the selection of natural suppressors of the brown spot disease in rice. We performed biochemical (E1), molecular antagonism (E2) and severity suppression (E3) studies under laboratory and greenhouse conditions. The E1, E2 and E3 assays were performed with 21 isolates. The experimental design was completely randomized with three replicates. E1 characterized all 21 isolates for the production of extracellular enzymes, siderophores, biofilm, indole‐3‐acetic acid (IAA) and phosphate solubilization. E2 was conducted to test the in vitro antagonism between the 21 isolates and B. oryzae, and E3 was conducted under greenhouse conditions, where seeds of the rice cultivars BRS‐Primavera and Esmeralda were sown in plastic trays containing 3 kg of fertilized soil. After 45 days, rice leaves were sprayed and inoculated with a mixed suspension of bacterial cells (1 × 108 CFU) and B. oryzae. All of the 21 bacterial isolates produced lipase, N‐fixation, siderophore, IAA, biofilm and solubilized phosphorus. Bacillus cereus, Priestia megaterium, Stenotrophomonas nitritireducens, Serratia marcescens and Serratia nematodiphila reduced radial colony growth of B. oryzae and suppressed brown spot severity by up to 90%. This indicates the potential of these isolates for biocontrol of brown spot in rice as a component of rice disease management.

Screening of heavy metal-resistant rhizobial and non-rhizobial microflora isolated from Trifolium sp. growing in mining areas.

Plant growth-promoting rhizobacteria (PGPR) can promote plant growth and development with several beneficial effects, especially in challenging environmental conditions, such as the presence of toxic contaminants. In this study, 49 isolates obtained from Trifolium sp. nodules growing on a Pb/Zn mine site were characterized for PGP traits including siderophores production, phosphate solubilization, extracellular enzymes production, and antifungal activity. The isolates were also screened for their ability to grow at increasing concentrations of NaCl and heavy metals, including lead, zinc, cobalt, copper, nickel, cadmium, and chromium. The findings of our study indicated that isolates Cupriavidus paucula RSCup01-RSCup08, Providencia rettgeri RSPro01, Pseudomonas putida RSPs01, Pseudomonas thivervalensis RSPs03-RSPs09, and Acinetobacter beijerinckii RSAci01 showed several key traits crucial for promoting plant growth, thus demonstrating the greatest potential. Most isolates displayed resistance to salt and heavy metals. Notably, Staphylococcus xylosus RSSta01, Pseudomonas sp. RSPs02, Micrococcus yunnanensis RSMicc01, and Kocuria dechangensis RSKoc01 demonstrated a significant capacity to grow at salt concentrations ranging from 10 to 20%, and isolates including Cupravidus paucula RSCup01-RSCup08 exhibited resistance to high levels of heavy metals, up to 1300 mg/L Pb++, 1200 mg/L Zn++, 1000 mg/L Ni++, 1000 mg/L Cd++, 500 mg/L Cu++, 400 mg/L Co++, and 50 mg/L CrVI+. Additionally, the analysis revealed that metal-resistant genes pbrA, czcD, and nccA were exclusively detected in the Cupriavidus paucula RSCup01 strain. The results of this study provide insights into the potential of plant growth-promoting rhizobacteria strains that might be used as inoculants to improve phytoremediation in heavy metal-contaminated soils.

Assessment of Proteinase and Phospholipases Enzymes Isolated from Pathogenic Candida species from Women Attending Antenatal Clinic at Mbeya Zonal Referral Hospital, Southern Highland Regions of Tanzania

Fungi are a global cause of vaginal infections, with vaginal candidiasis largely afflicting tropical regions including most parts of sub-Saharan Africa. In Tanzania, baseline studies have established the prevalence of Candida species among symptomatic and asymptomatic pregnant women in Dar es Salaam (Namkinga et al., 2005; Namkinga 2012) and in Mwanza (Mushi et al., 2019). However, no study that has been done to determine the above-mentioned enzymes form Candida species in Southern Highland Regions of Tanzania. Several factors have been reported to contribute to the virulence and pathogenicity of Candida, among others the production of extracellular hydrolytic enzymes, particularly phospholipase and proteinase. Therefore, this study was designed to investigate the in vitro production of phospholipases and proteinases enzymes from isolated pathogenic Candida spp from pregnant women.Of the 280 samples collected from symptomatic and asymptomatic pregnant women attending antenatal clinics at Mbeya Zonal Referral Hospital were tested for several microbiological methods such as the wet mount microscopic preparations (hanging drop) and the Gram stained smears for microscopy, cultures on Sabouraud’s dextrose agar and on Conidia enhancing medium (Corn meal agar), germ tube test, biochemical tests, sugar fermentation-assimilation tests and molecular test to characterize Candida species.Phospholipase production was performed in egg yolk medium while the production of proteinase was done in a medium containing bovine serum albumin. All analyses were performed in triplicates. The results showed that; out of the 280 tested, 155 (74.3%) isolates were phospholipase positive while 201 (96.6%) were positive for proteinase activity. C. albicans was the species with the highest number of positive isolates for proteinase and phospholipase 110 (95.6%), and most strains of C. albicans produce both enzymes (phospholipases and proteinases). The non-albicans Candida isolates were also producers of hydrolytic enzymes that, consequently, might be able to cause infections as favorable conditions arises.

Screening and characterization of thermostable enzyme-producing bacteria from selected hot springs of Ethiopia.

Thermostable microbial enzymes play an important role in industries due to their stability under harsh environmental conditions, including extreme temperatures. Despite their huge application in different industries, however, the thermostable enzymes of thermophilic microorganism origin have not yet been fully explored in Ethiopia. Here, we explored thermophilic bacteria and their enzymes from selected hot spring water and sediment samples. Accordingly, thermophilic bacteria were isolated and screened for the production of extracellular hydrolytic enzymes. Promising numbers of isolates were found as producers of the enzymes. The potent enzyme producers were further identified using matrix-assisted laser desorption/ionization time-of-flight-mass spectrometry analysis and 16S rRNA gene sequencing. The findings revealed the presence of potential hydrolytic enzyme-producing thermophilic bacteria in hot springs of Ethiopia and necessitate further comprehensive study involving other extreme environments. Our findings also revealed the potential of Ethiopian hot springs in the production of thermostable enzymes of significant application in different industries, including food industries.

Biotechnological insights into extracellular enzyme production by thermotolerant fungi from hot springs and caves: Morphology, pellets formation, and protease production.

This study investigates the thermotolerant fungal biodiversity in caves and hot springs, focusing on their potential for extracellular enzyme production, specifically proteases. Samples were collected from the Cardonal region in Hidalgo, Mexico, using three different isolation methods. The study characterizes the morphological diversity of the isolated fungi and identifies various genera, including Aspergillus, Penicillium, Trichoderma, Cladosporium, and Fusarium, based on morphology. The isolated fungi were screened for their ability to produce extracellular enzymes on solid media, with a particular emphasis on proteases due to their industrial significance. Among the 35 isolated fungi, 20 exhibited proteolytic activity, and 12 strains were identified as good protease producers based on enzymatic index values. The study also evaluated the formation of fungal pellets by proteolytic fungi and found certain strains to display significant pellet formation. Additionally, protease production was examined by fungal pellets in submerged cultures, with isolate 6 demonstrating the highest protease activity. The findings highlight the diverse thermotolerant fungal biodiversity in extreme environments, and emphasize their potential for enzymatic production. This research contributes to our understanding of fungal ecology and provides insights into the biotechnological applications of these enzymes. The study recommends further molecular investigations to enhance biodiversity studies in such extreme environments.

Bioprospecting of endophytic fungi from medicinal plant Anisomeles indica L. for their diverse role in agricultural and industrial sectors

Endophytes are microorganisms that inhabit various plant parts and cause no damage to the host plants. During the last few years, a number of novel endophytic fungi have been isolated and identified from medicinal plants and were found to be utilized as bio-stimulants and bio fertilizers. In lieu of this, the present study aims to isolate and identify endophytic fungi associated with the leaves of Anisomeles indica L. an important medicinal plant of the Terai-Duars region of West Bengal. A total of ten endophytic fungi were isolated from the leaves of A. indica and five were identified using ITS1/ITS4 sequencing based on their ability for plant growth promotion, secondary metabolite production, and extracellular enzyme production. Endophytic fungal isolates were identified as Colletotrichum yulongense Ai1, Colletotrichum cobbittiense Ai2, Colletotrichum alienum Ai2.1, Colletotrichum cobbittiense Ai3, and Fusarium equiseti. Five isolates tested positive for their plant growth promotion potential, while isolates Ai4. Ai1, Ai2, and Ai2.1 showed significant production of secondary metabolites viz. alkaloids, phenolics, flavonoids, saponins, etc. Isolate Ai2 showed maximum total phenolic concentration (25.98 mg g−1), while isolate Ai4 showed maximum total flavonoid concentration (20.10 mg g−1). Significant results were observed for the production of extracellular enzymes such as cellulases, amylases, laccases, lipases, etc. The isolates significantly influenced the seed germination percentage of tomato seedlings and augmented their growth and development under in vitro assay. The present work comprehensively tested these isolates and ascertained their huge application for the commercial utilization of these isolates both in the agricultural and industrial sectors.

Microbial electrochemical composting: A sustainable strategy to enhance lignocellulose conversion into humus

Achieving satisfactory levels of humification during composting is recognised as a challenge due to the recalcitrance of lignocellulose and the uncertainty of current biofortification techniques. Therefore, a novel microbial electrochemical composting technology was developed from insights into microbiology and electrochemistry in this study to strengthen microorganisms’ function promoting the conversion from lignocellulose into humus. Firstly, a fungus (Aspergillus oryzae) was introduced which exhibited a higher propagation rate (29.9%) and secreted more lignocellulose-degrading enzymes (18.9–74.9%) under electric field assistance. Subsequently, an in-situ composting trial was conducted with supplementary electric fields simultaneously combined with Aspergillus oryzae inoculation. The abundance of Aspergillus oryzae increased 3.0–7.8-fold under the influence of electric field, which enabled the production of more extracellular enzymes (by 8.4–149.5%) to promote the conversion of lignocellulose to humus (increased by 7.0–20.2%). The results indicated electric field can act as an activator of Aspergillus oryzae and magnify its function. It provides an innovative and efficient technique for enhancing humification during composting that contributes to the conversion of organic waste into high-quality soil conditioner products.

Revealing the impact of Rapamycin on the virulence factors of the Candida haemulonii complex

The incidence of invasive fungal infections caused by Candida species is increasing, particularly in immunocompromised individuals. This increasing incidence poses a dual challenge, comprising escalating antifungal resistance and the necessity for accurate fungal identification. The Candida haemulonii complex further complicates these challenges due to limited identification tools. Like some other Candida species, infections involving this complex show resistance to multiple antifungals, requiring innovative therapeutic approaches. Rapamycin, known for its antifungal properties and immunosuppressive characteristics, was investigated against the C. haemulonii complex species. Results revealed a rapamycin minimal inhibitory concentration (MIC) range of 0.07 to >20 µM, with fungicidal effects in most strains. In vitro analyses using the rapamycin maximum plasma concentration (0.016 µM) showed reduced surface properties and decreased production of extracellular enzymes. Rapamycin also hindered biofilm formation by some strains. Even when treated at the human therapeutic dose, which is lower than the MIC, phenotypic variations in C. haemulonii were detected, hinting at the possible attenuation of some virulence factors when exposed to rapamycin.