Enzymatic and antimicrobial potential of Actinomycetota species from mangrove sediments in Tanzania

The enzymatic and antimicrobial potential of Actinomycetota species present in mangrove sediments at Bagamoyo in Tanzania was explored. Ten strains were isolated from sediments and identified based on morphological and biochemical characteristics. All isolates were Gram positive and catalase positive. Eight isolates tested positive for amylase production. Crude extracts from five isolates showed antimicrobial activities in at least one of the five tested micro-organisms, with MIC values ranging from 10 to 2.5 mg/mL. The 16S rRNA gene region of the five isolates was sequenced, and DNA barcoding revealed that the isolates belong to the genera Streptomyces (3 strains), Micrococcus (1 strain) and Hoyosella (1 strain). The Hoyosella isolate is reported here for the first time from Western Indian Ocean mangrove systems. The identified Actinomycetota have demonstrated capabilities to ferment sugars, produce enzymes and secondary metabolites with antimicrobial properties, with potential application in pharmaceutical, agricultural and biotechnological industries.


Introduction
The microbes inhabiting different extreme environments such as the mangroves, deserts, hot springs and salt lake ecosystems have been a focus in search for novel pharmaceutical compounds to treat existing and emerging diseases (Khadayat et al., 2020).Marine ecosystems are well defined for their unique biotic and abiotic components.Even though the number of marine ecosystems is actively debated, most ecologists agree on six; namely, estuaries, salt marshes, mangrove forests, coral reefs, open ocean and the deep-sea ocean (Duarte et al., 2020).Mangroves are groups of trees and shrubs that grow in the coastal intertidal zone of marine environments.In the Western Indian Ocean (WIO) region, mangroves are estimated to cover approximately 1.0 million ha, constituting about 5 % of global mangrove coverage (Maina et al., 2021).Ninety per cent of mangroves in the WIO region occur in deltas and estuarine in the four countries of Mozambique, Madagascar, Tanzania and Kenya, in decreasing order of coverage (Mangora et al., 2016).The mangrove ecosystems are among the world's most productive environments that provide a huge but scarcely explored source of microbes, including Actinomycetota, with high potential to produce bioactive secondary metabolites such as antimicrobial, anticancer and anticardiovascular agents (Salimi et al., 2018;Siddharth and Rai, 2019;Cera et al., 2022).
Actinomycetota is a phylum of Gram-positive bacteria characterized by the presence of high guanine and cytosine content in their DNA.The first discovery of species in this group of bacteria was made in 1877 (Goodfellow, 2012).Actinomycetia is the common class of phylum Actinomycetota comprising of 16 orders including order Actinomycetales which is often called Actinomycetes, with most of its species having been reported to produce secondary metabolites with biomedical properties (Ranjani et al., 2016).The most common genera of Actinomycetales are Streptomyces, Nocardia and Micromonospora (Ranjani et al., 2016).
Actinomycetota occur either as spores or vegetative forms in terrestrial habitats such as soil, plant litter and composts as well as in aquatic environments such as marine and freshwater.
Ecologically, species in phylum Actinomycetota play a vital role in various biological processes such as bioremediation (Adenan and Ting, 2022) and promotion of plant growth (Soumare et al., 2021).Over decades, marine Actinomycetota have been used as an outstanding source of enzymes and bioactive metabolites.Physiological parameters such as pH, temperature, salt concentration and atmospheric conditions are some of the factors that affect their production of enzymes and biomedically important metabolites (Sadikiel et al., 2022).Enzymes produced by most acidophilic Actinomycetota are hydroxylases, transferases and esterase (López-Mondéjar et al., 2019), while those produced by thermophilic and alkaliphilic species include amylases, proteases, keratinases, xylanase and dextranase (López-Mondéjar et al., 2019;Lema et al., 2022).Actinomycetota from the WIO region have been found to exhibit significant enzymatic diversity with biotechnological potential (Sarkar and Suthindhiran 2022).These enzymes include proteases, lipases, cellulases, amylases and keratinases (González et al., 2020).Moreover, research on marine Actinomycetota from the WIO coastline revealed their significance as producers of compounds, emphasizing their pharmaceutical importance (Kamjam et al., 2017).Therefore, this study was designed to explore the enzymatic and antimicrobial potential of Actinomycetota species inhabiting the mangrove sediments on the Bagamoyo coast of Tanzania to provide baseline information useful in the development of enzyme-derived biotechnologies and novel antibacterial agents.

Sample collection
Sampling was carried out in the mangrove forest in the intertidal zone of Indian Ocean coast of Bagamoyo District, Pwani region, Tanzania at approximately Longitude 38° 53' 55.772'' E and Latitude 6° 25' 46.548'' S (Fig. 1).The sediments samples were collected in January 2022 using a syringe barrel from 10 points at a depth of 10 cm within a 100 m 2 area of the mangrove.
The sediments were placed into sterile polythene bags, mixed well and then taken to the laboratory at the Department of Molecular Biology and Biotechnology (DMBB) at the University of Dar es Salaam (UDSM) for further analysis.

Isolation of Actinomycetota
One gram (1.0 g) of the sediments samples was suspended in 9 ml of sterile sea water and serially diluted to 10 -4 as previously described by Sosovele et al. (2012).
The diluted samples were placed on to a set of selective isolation plates in triplicates.The selective isolation plates contained starch casein agar (SCA) media constituting of 10.0 g starch, 1.0 g casein, 15.0 g agar, 500 mL sea water (Obtained from the sampling site) and 500 mL distilled water adjusted to pH 7.0 ± 0.1.Media was autoclaved at 121 °C for 15 minutes then supplemented with nalidixic acid (20 μg/mL) and nystatin (50 mg/mL) antibiotics to suppress the growth of bacteria and fungi, respectively without affecting the growth of Actinomycetota (Sosovele et al., 2012).The inoculated plates were incubated at 28 °C for 2 weeks.Isolation was carried out by randomly picking developed colonies from selected dilution plates based on colony morphology followed by repeated serial dilution and streaking techniques until pure colonies were obtained.

Morphological identification of the Actinomycetota isolates
Morphological characterization of Actinomycetota isolates was carried out macroscopically by observing colony colour, aerial mycelium, texture, elevation as well as pigment production and microscopically by observing cell morphology and Gram's staining test (Lema et al., 2022).

Biochemical characterization of the Actinomycetota isolates
Actinomycetota isolates were subjected to carbohydrate fermentation, catalase and amylase production as hereunder described.

Carbohydrate fermentation test
The isolated Actinomycetota were screened for their ability to ferment D-glucose, sucrose and starch in broth media (10.0 g peptone, 5.0 g NaCl, 1.0 g beef extract, 0.018 g phenol red, 10.0 g carbon source, 1 L distilled water.pH 10) (Remya and Vijayakumar, 2008).The isolates were placed in sterile test tubes containing sterilized broth media and incubated at 37 °C.Observation was conducted after 48 hours through examining the colour change of the broth.

Catalase test
A slide method catalase test was conducted as described by Reiner (2010), where a sterile wire loop was used to collect a small amount of organism from a pure culture and placed onto a sterile microscope slide.Observation was made immediately after addition of 1 drop of 3 % H 2 O 2 on a microscope slide containing a bacteria smear.

Amylase test
The isolated bacteria were tested to determine if they could hydrolyze starch by producing amylase enzyme.According to Mahboobeh et al. (2016), starch agar media (2.0 g soluble starch, 5.0 g peptone, 0.5 g yeast extract, 0.5 g beef extract, 5.0 g sodium chloride, 1000 mL distilled water, pH 7.4) was used to grow the isolates, whereby each isolate was spotted on the media and left to grow for 48 hours at 37 o C.After incubation, the surface of the plate was flooded with iodine solution using a dropper for 30 seconds then observed to check if there was a clear zone formed around the bacteria isolates or not.

Production of secondary metabolites
Each of the selected Actinomycetota isolate's pure culture was cultivated in 15 L production broth (24 g soluble starch, 3.0 g meat extracts, 5.0 g yeast extracts, 3.0 g peptone, 1.0 g glucose, 4.0 g CaCO 3 1000 mL distilled water, pH 7.0).After 14 days, bacterial extract was filtered followed by the addition of equal volume of ethyl acetate for metabolites extraction.The mixture was shaken vigorously for 15 minutes then subjected to a separating funnel and the organic layer comprising the secondary metabolites was collected.Solvent contained in the crude extracts was removed using a rotary evaporator at 40 °C.The recovered extracts were stored in the refrigerator until required for antimicrobial assays.

Minimum inhibitory concentration of the extracts
Minimum inhibitory concentration (MIC) of the active crude extracts was evaluated using a 96-well microtiter plate assay method following the procedure previously described by Masalu et al. (2020), with modifications.Fresh cultured test bacteria were inoculated in 100 mL of Mueller Hinton and incubated for 24 h at 37 °C prior to the experiment.Using sterile 96 microtiter plates, two-fold serial dilution was carried out to obtain 100 μL per well of the following concentrations: 10, 5.0, 2.5, 1.25, 0.625, 0.313, 0.156 and 0.078 mg/mL.Then, 100 μL of Mueller Hinton broth inoculated with standardized 0.5 McFarland test organisms was added into each well to make a total of 200 μL per well.Microtiter wells with broth only were set for sterility control.Chloramphenical and Fluconazole were used as positive controls for bacteria and fungal respectively.Microtiter plates were incubated at 37 °C for 24 h.The MIC results were determined using a micro plate reader (ELISA plate analyser).

Molecular identification of the selected Actinomycetota isolates
The five Actinomycetota isolates whose extracts showed antimicrobial activities were selected for molecular identification using 16S rRNA gene sequencing.DNA extraction and purification was done by using Quick-DNA™ Fungal/Bacterial Miniprepkit as per manufacturer's protocol (Cat No. D6005, Zymoresearch Corp. USA).Quality and quantity of the DNA obtained (ng/μL) (A260/A280) were measured using a UV-Vis NanoDrop spectrophotometer.16S rRNA gene was amplified using the universal eubacterial primers 27F (5ʼ-AGAGTTTGATCCTGGCTCAG-3ʼ) and 1492R (5ʼ-GGTTACCTTGTTACGACTT-3ʼ) (Sengupta et al., 2015).All PCR amplifications were performed at a total volume of 25 μl containing 12.5 μl of master mix, 1.0 μl forward primer, 1.0 μl of reverse primer, 3 μl template DNA and 7.5 μl of nuclease-free water.DNA was amplified by using Veriti™ 96-Well Fast Thermal Cycler (ThermoFisher Scientific, USA) (Stach et al., 2003).The Amplification programme was initiated by denaturation at 94 °C for 4 minutes, followed by 35 cycles of denaturation at 94 °C for 30 seconds, annealing at 60 °C for 50 seconds, and extension at 68 °C for 1 minute.
A final extension was performed at 68 °C for 5 minutes.

Phylogenetic analysis
Quality control check of the identified sequences was performed using Chromas Version 2.6.6 (Technelysium Pty Ltd., Australia) prior to analysis.Sequence alignment was carried out using AliView Version 1.26 (Uppsala Universitet) by the MUSCLE method.
The alignment analyses were later crosschecked with Molecular Evolutionary Genetics Analysis X (MEGAX) version 10.0.5, the phylogenetic tree was also constructed using the MEGAX programme with the Tamura-Nei distancing model, maximum likelihood as statistical method, Nearest-Neighbor-Interchange as maximum likelihood Heuristic Method tree inference option (Kumar et al., 2018).

Isolation of Actinomycetota
Observation of the inoculated samples on SCA selective media done after 14 days of incubation showed growth of distinct bacteria colonies, some of which showed powdery consistency and firmly attached to the agar surface projecting a tangled mass of mycelium resembling fungi, while some had a smooth waxy appearance with different colours such as white, yellow, brown, grey, pink and cream (Fig. 2 a-c).
The observed cultures were highly suspected to be Actinomycetota as most of the features such as the cream colony colour for Hoyosella species and mycelia projection for Streptomyces species were as described in various related literature ( Jurado et al., 2009;El-Naggar et al., 2016).The colonies were randomly picked based on their colour, texture, pigmentation and elevation from the mixed cultures and were sub-cultured until a single strain grew in each plate as presented in Figure 2 d-f.Upon repeated transfers to new media, 10 isolates were selected for morphological, biochemical and antimicrobial characterization.

Morphological and biochemical characteristics of the selected Actinomycetota isolates
The 10 selected isolates were first characterized based on morphology and the results are shown in Table I.
The isolated colonies had varying colour, texture, pigmentation and elevation.Some colonies were hairy    (Hasani et al., 2014).As such, these findings show that the isolates belonged to 6 different genera with Streptomyces (isolates WP27F, WZ27F and P27F) being in the majority (Table 1).
Results of the biochemical tests (Table 2) revealed that the majority of the selected Actinomycetota species fermented sugars.All isolates were able to ferment D-glucose and sucrose sugars and tested positive for catalase enzyme production.Of the 10 isolates, eight were able ferment starch and tested positive for amylase enzyme production.

Antimicrobial activities of the extracts
Out of the 10 tested isolates' extract, five coded WP27F, WZ27F, C27F, P27F and Y27F showed significant antimicrobial activity against all tested microorganisms as presented in Table 3.The highest inhibition zone was 20.7 mm exhibited by the extracts of WP27F strain against C. albicans (Fig. 2a).This strain (WP27F) also showed high activity (18.3 mm) against Gram-negative bacteria E. coli followed by the extracts from P27F strain which showed inhibition zones of 16.0 mm against both E. coli and S. typhi (Table 3, Fig. 3c).
The extracts from isolates WP27F, WZ27F, C27F, P27F and Y27F were subjected to determination of the minimum inhibitory concentrations (MICs) against the test microorganisms, the results of which are shown in Table 4.The MIC values ranged from 2.5 to 10 mg/mL.

Molecular identification of the selected Actinomycetota isolates
16S rRNA gene sequencing of the isolates whose extracts showed significant antimicrobial potential possessed percentage similarities of 99-100 to their

Morphological and biochemical characteristics of the isolated Actinomycetota
Morphological characterization revealed that the majority of the isolates formed white colonies similar to the study conducted by Rahman (2008).Isolates with white colour and mycelia projections were highly suspected to be Streptomyces species as described by Khadayat et al. (2020), however, there are some studies that have reported on the Streptomyces species with other colours such as pink and grey (Mohamed et al., 2017).The colony features of strain WP27F (ON954769) and P27F (ON955761) resembled those of S. chumphonensis (AB738400) and Streptomyces sp.
The non-Streptomyces species displayed different colony colours; the literature suggests the strains with cream colour and smooth appearance to be of genus Hoyosella ( Jurado et al., 2009) and cream with rough texture to be of genus Streptacidiphilus (Cho et al. 2012).The morphological description of isolate C27F (ON954771) fits that of Hoyosella altamirensis (FJ179485) with the colony appearing cream, circular and smooth as reported by Jurado et al. (2009).Isolates Y27F (ON955268) and PY27F macroscopic features resembled those of Micrococcus luteus (Greenblatt et al., 2004;Shahin et al., 2022).
The brown colonies with a rough texture belonged to genus Rhodococcus (Cho et al., 2012) while those that were white with a smooth texture were from the genus Nocardioides (Siddharth and Rai, 2019).
These results showed that all Streptomyces species were able to ferment sugars agreeing with the study conducted by Charousová et al. (2017).The biochemical characteristics of strains WP27F (ON954769), P27F (ON955761) and WZ27F (ON954770) such as the ability to hydrolyze starch has been reported from Streptomyces  and S. fradiae (KJ467538) respectively, with both strains originating from the sediment samples (Rahman, 2008;Phongsopitanun et al., 2014;Gopikrishnan et al., 2016).Streptomyces species are well known for the production of amylase and catalase enzymes (Taha et al., 2021).In the current study, all Streptomyces species were capable of producing amylase and catalase enzymes.

Biochemical analysis of species in genera Hoyosella
reveal that these species are capable of fermenting sugars.Hamada et al. (2016) reported on the glucose and inositol utilizing H. altamirensis species.In the current study, isolate C27F was able to ferment glucose, sucrose and starch sugars.Moreover, it showed the ability to produce amylase and catalase enzymes similar to the observations made in other related studies (Hamada et al., 2016;Lema et al., 2022) Genus Streptacidiphilus is among the rare genera of phylum Actinomycetota (Kim et al., 2012).Some of species in this have reported to degrade various forms of carbohydrates (Malik et al., 2020).In this study, isolate WS27F was observed to ferment glucose, sucrose and starch sugars.
Nocardioides species have been reported to ferment arabinose, fructose, galactose, lactose, maltose, mannose and sucrose (Abdulla, 2009).Isolate CS27F showed the ability to ferment glucose and sucrose but tested negative for starch hydrolysis, similar to the study reported by Wang et al. (2016) on Nocardioides Nocardioides species (Kubota et al., 2005).
The studied Rhodococcus species (G27F and B27F) tested positive for fermenting all carbon sources agreeing with the study conducted by Fei et al. (2015).
The isolates tested positive for the production of catalase enzyme as observed for strain Rhodococcus fascians (Gesheva al., 2010) but isolate B27F tested negative for the production of amylase enzyme.The inability of the strain B27F to produce amylase enzyme is in contrast with the observations made in the study conducted by Ghimire et al. (2021) on the endophytic Rhodococcus species.Such variations might be contributed to by inter-species differences.
Micrococcus species showed the ability to ferment the tested carbon sources with variations between the similar species.Isolate Y27F was able to utilize all carbon sources unlike isolate PY27F which was unable to utilize starch.Isolates Y27F and PY27F showed the ability to produce catalase enzyme similar to the Micrococcus species studied by Bannerman and Peacock (2006).
For amylase production, isolate Y27F tested positive agreeing with the study reported by Fan et al. (2009) while isolate PY27F tested negative.These interspecies variations have also been reported in other Micrococcus species (Singh et al., 2014).The catalase enzyme produced by M. luteus has been reported to significantly increase under stress (Ravikumar et al., 2007).
The identified species from Bagamoyo mangroves have demonstrated their capability to ferment sugars and produce enzymes which can be applied in various fields including pharmaceutical, agricultural and biofuel industries, reminiscent of those observed in related studies (Gesheva et al., 2010;Loux et al., 2015).

Molecular identification of the selected Actinomycetota isolates
The phylogenic characteristics of the five selected strains based on 16S rRNA gene sequencing showed Lederbergia lenta (AB021189) was used as an outgroup to position the root of the tree.
tumenensis (KC122242) isolated from rhizosphere and non-rhizosphere soil of cotton fields in India (Rai and Singh, 2012) and 99.24 % resemblance to S. tumenensis (AM180560) isolated from soil in China (Chen et al., 2005).Little is known on the presence of this species in WIO regions.

Antimicrobial activities of the extracts
Several authors have reported on the antimicrobial activities of the extracts from Actinomycetota species (Khadayat et al., 2020;Cera et al., 2022).In this study, that have been reported to possess antimicrobial and antitumor properties (Martín and Liras, 2022).The production of secondary metabolites by S. chumphonensis is reported by Phongsopitanun et al. (2021).
When the extracts were screened against gram-posi- against various pathogens including C. albicans has been previously reported (Shahin et al., 2022).Moreover, the pigments produced by M. luteus isolated from the marine environment in India have been reported to possess antimicrobial activities against P. aeruginosa, K. pneumoniae, E. coli and Aspergillus niger with inhibition zones of 12, 9, 14 and 17 mm, respectively (Balan et al., 2019).
In the current study, the majority of the non-Streptomyces species showed weak or no bioactivity against the pathogenic microbes, however, there are some studies reporting on the antimicrobial activities of such other species belonging to genera Nocardioides (Siddharth and Rai, 2019), Streptacidiphilus (Yu et al., 2021) and Rhodococcus (Zampolli et al., 2022).Overall results of antimicrobial screening in this study revealed that the extracts from the isolates belonging to genera Streptomyces, Hoyosella and Micrococcus exhibited activity against the test pathogenic microbes.

Conclusions
This study aimed at isolating and identifying Actin- Testing strains, Escherichia coli ATCC-8739, Salmonella typhi ATCC-14028, Bacillus subtilis ATCC-6633, Staphylococcus aureus ATCC-25923 and Candida albicans ATCC-10231 were obtained from the microbial strains' library at the DMBB laboratory.The bacteria and yeast were streaked on nutrient agar (NA) and potato dextrose agar (PDA), respectively then incubated at 37 °C for 24 hours.After incubation, pure cultures were picked and transferred in test tubes containing sterile saline (0.85 %) then centrifuged.The turbidity of bacterial cells observed was compared with 0.5 McFarland standard.

Figure 1 .
Figure 1.A map showing location of the sampling site at Bagamoyo, Tanzania.
Disc diffusion assay was used to screen for antimicrobial activities of the crude extracts from Actinomycetota isolates against the test microorganisms as previously described byChanthasena et al. (2022) Twenty microliter (20 μl) of the isolate's crude extracts (300 mg/mL) were impregnated in sterile 6 mm discs prepared from Whatman No. 1 filter paper.Test bacteria suspensions were swabbed on the sterile nutrient agar plates followed by the addition of the negative control discs containing DMSO, discs soaked with test samples and finally discs with chloramphenicol (1 mg/mL) and fluconazole (1 mg/mL) as positive control for the bacteria and yeast respectively.The petri dishes were incubated for 24 hours at 37 o C. Results were obtained by measuring the diameter of the inhibition zone (mm), if any.
The PCR products were sequenced at a commercial genomics facility, Inqaba Biotec in South Africa, using the BrilliantDye™ Terminator Cycle Sequencing Kit V3.1, BRD3-100/1000 (Nimagen) according to the manufacturer's instructions.The products were then cleaned by following the protocol of the ZR-96 DNA Sequencing Clean-up Kit (Cat No. D4053, Zymoresearch Corp. USA).The purified products were inserted on the Applied Biosystems™ ABI 3500xL Genetic Analyzer (Cat No. 4406016, ThermoFisher Scientific) and forward sequenced only with a 50 cm array, using POP-7™ as compatible polymer.Sequence chromatogram analysis was performed using FinchTV analysis software v1.4.0.

Figure 4 .
Figure 4. Phylogenetic affiliations of partial (≈1200 bp) 16S rRNA gene sequences of Actinomycetota isolates retrieved from Bagamoyo mangrove sediments and the strains of the most closely related genera.The inference tree was constructed through MEGAX using the Tamura-Nei as a substitution method, maximum likelihood as a statistical method, and nearest-neighbor interchange as a maximum likelihood heuristic method.Bootstrap values are expressed as percentages, based on 1 000 resampling of data.Bootstrap values, >50 % are shown at branch points.
extracts from five isolates belonging to genus Streptomyces (3), Hoyosella (1) and Micrococcus (1) showed the most bioactivity against all tested microorganisms, whereas, two isolates belonging to genus Rhodococcus and Nocardioides showed activity to at least one of the five test micro-organisms.On the other hand, three isolates of genus Streptacidiphilus (1), Rhodococcus (1) and Micrococcus (1) did not show any activity at the tested concentration.Species in genera Streptomyces are well known for the production of bioactive extracts comprising of various classes of secondary metabolites including alkaloids, dilactones, flavonoids and diketopiperazines omycetota species inhabiting the sediments of Bagamoyo mangroves in Tanzania in the WIO region with the ultimate goal of unravelling their enzymatic and antimicrobial potentials.Ten strains of Actinomycetota were isolated and identified to belong to six genera, namely Streptomyces, Nocardioides, Hoyosella, Streptacidiphilus, Rhodococcus, and Micrococcus.The identified species demonstrated their capability to produce enzymes which can be applied in various fields including pharmaceutical, agricultural, biofuel and biotechnological industries.Crude extracts from the selected five strains that were finally molecularly identified as Streptomyces chumphonensis WP27F (ON954769), Streptomyces fradiae WZ27F (ON954770), Streptomyces tumenensis P27F (ON955761), Micrococcus luteus Y27F (ON955268) and Hoyosella altamirensis C27F (ON954771) portrayed biomedical potency against pathogenic microbes.The study marks the first report on the identification of Streptomyces tumenensis species in Africa and the first work on the isolation of Hoyosella species from the WIO region.The findings warrant further explorations of the secondary metabolites from such ecosystem as source of biomedical and other industrially important agents.

Table 1 .
Morphological characteristics of the selected Actinomycetota isolates.

Table 2 .
Biochemical characteristics of the selected Actinomycetota isolates.

Table 4 .
MIC (in mg/mL) of the extracts from the selected Actinomycetota isolates.

Table 5 .
BLASTn results for sequences of isolated Actinomycetota strains and their closest matches in GenBank.
Key: % sequence similarity = percentage sequence, AN = accession number rotundus species isolated from deep sea water.The ability of isolate C27F to produce catalase enzyme and amylase enzymes has also been observed in other Lema et al. (2022)albicans with MIC of 10.0 mg/mL.The MIC of H. altamirensis C27F extracts against S. aureus was observed to be above 10 mg/mL.Little is known on the bioactivity of the extracts fromHoyosella species, however,Lema et al. (2022)reported on the bioactivity of this species with comparable observations against E. coli and S. aureus.Extracts from M. luteus Y27F (ON955268) showed moderate antimicrobial activities against all tested microorganisms unlike those from isolate PY27F which did not show any activity at the tested concentration.The MIC of Y27F (ON955268) extracts against S. typhi and C. albicans was 10.0 mg/mL whereas against B. subtilis, S. aureus and E. coli was observed to be above 10.0 mg/ mL.The bioactivities of M. luteus Y27F (ON955268) (Drautz et al., 1986)0)albicans (5.0 mg/mL) and E. coli (10.0 mg/mL) but did not show any activity against B. subtilis at the concentration < 10 mg/mL.Streptomyces sp.(LC427864) that was 95.78 % related to the isolate of S. tumenensis P27F (ON955761) from the present study was reported to have moderate antimicrobial activity against S. aureus, E. coli, and S. typhi(Khadayat et al., 2020).The inhibition zone of the extracts from S. tumenensis P27F (ON955761) against E. coli was 13.0 mm which is comparable to that of Streptomyces sp.(LC427864) (10 -13 mm) against 12 strains of E. coli(Khadayat et al., 2020).Extracts from the isolate from S. fradiae WZ27F (ON954770) showed antimicrobial activity against pathogenic microbes B. subtilis,S.aureus, S. typhi, E. coli and C. albicans with inhibition   et al., 2009).In Tanzania, the secondary metabolites isolated from S. fradiae in 1986 were found to be active against gram-positive bacteria including B. subtilis and B. brevis as well as displaying anticancer properties against stem cells of murine L1210 leukemia(Drautz et al., 1986).