BIOTECHNOLOGY, ENVIRONMENT, AND BIODIVERSITY

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​PSBMB Scientific Posters Committee
BEB-01

MICROENCAPSULATION OF Pediococcus acidilactici IN
​CHITOSAN/POLYANILINE COMPOSITE

JOANNE O. ANCAJAS and LESLIE MICHELLE M. DALMACIO
ABSTRACT

​Microencapsulation is among several methods and strategies that are being developed to protect probiotic bacteria against adverse environmental conditions in the stomach and increase their recovery rates. This study aims to determine the potential microencapsulation and delivery of Pediococcus acidilactici in Chitosan/Polyaniline composite, wherein ionic gelation through extrusion method of microencapsulation is used. It also determined the shelf life and viability of the microencapsulated probiotic. Results show that the optimal CS/PANI ratio that could encapsulate Pediococcus acidilactici is 3%/0.5% extruded in 1% sodium citrate. The number of probiotic cells that has been entrapped per microbead is 1.61 x 106 Cfu/ml ± 0.08. The microencapsulated probiotic was subjected to simulated gastrointestinal (GI) conditions to determine survival through GI transit. The observed cell release of entrapped probiotics in the simulated gastric fluid is considerably higher than expected ranging from 105-106cumulative value due to the immediate swelling of the CS/PANI microbeads. However, at the end of exposure to the simulated intestinal fluid, the cumulative release is 106-107, indicating potential to be released in the gut. While it was found that the cell viability of microencapsulated (46.23%±0.02) probiotics is low as compared to the free cells (69.64%±0.04) after 30 days of storage at 4oC, the results at 30th day of storage at room temperature showed reciprocal findings for free cells (25.92±0.16) and microencapsulated (33.10±0.13). Therefore, microencapsulation of P. acidilactici can be a considerable means to achieve higher cell viability both in the course of gastrointestinal delivery and storing at room temperature.

Keyword: Microencapsulation, Pediococcus acidilactici, chitosan, polyaniline
BEB-02

CONSTRUCTION AND PHENOTYPIC AND MOLECULAR ASSESSMENT OF A BIDIRECTIONAL PLASMID VECTOR INCORPORATING THE ORYZA SATIVA L. SPP. JAPONICA BIP1 BIDIRECTIONAL PROMOTER AND ANTIBIOTIC RESISTANCE GENES

Thomas Gabriel H. Desengaño, Sofia Philine H. Abayon, Evangeline D. Pascual,
​Bernabeth Jo T. Tendero, and Jorge Gil C. Angeles
ABSTRACT

​Bidirectional promoters are promoters that allow dual direction gene expression. Often, plasmid vectors with unidirectional promoters are available thus, it would be more advantageous if plasmid vectors can drive gene expression in both directions. This study aims to construct a bidirectional plasmid vector utilizing antibiotic resistance genes and a reported bidirectional Oryza sativa L. spp. japonica (OsBIP1) promoter. The OsBIP1 promoter obtained from the Nipponbare variety and the ampicillin (amp) and chloramphenicol acetyltransferase (cat) antibiotic resistance reporter genes were amplified using primers appended with different restriction sites to facilitate directional ligation and employed optimized PCR conditions for annealing temperature (Tm) and MgCl2 and dNTP concentrations. The amplified OsBIP1 bidirectional promoter and these antibiotic resistance genes were restriction digested and directionally-ligated (OsBIP1-sense and OsBIP1-anti-sense orientations) into the pBI121 plasmid backbone using various insert:vector ratios to assess for promoter activity and directionality. The ligation products were transformed into competent E.coli DH5α and grown in media supplemented with ampicillin and/or chloramphenicol to phenotypically assess the developed bidirectional plasmid.
 
Cell growth was observed in the ampicillin-only and in the ampicillin-chloramphenicol plates. Maximal bacterial colony growth for OsBIP1-sense and OsBIP1-anti-sense on these double antibiotic plates was detected using the 1:1 insert:vector (v/v) ratio. PCR confirmation detected the expected amplicon for OsBIP1 promoter::amp using the extracted plasmid DNA from randomly-picked bacterial clones. The growth of the transformed bacteria in the double antibiotic plates and the detection of the expected OsBIP1 promoter::amp amplicon verifies the construction of the bidirectional vector. This bidirectional vector may be used as a baseline for future studies.

Keyword: bidirectional promoters, antibiotic resistance genes, plasmid vector, Oryza sativa, OsBIP
BEB-03

OLIGOSACCHARIDE PROFILING OF MILK COLOSTRUM FROM
​TWO BREEDS OF PORCINE

Jessica G. Asuncion, Connie A. Remoroza, Sara Yang , Tytus D. Mak, Yuxue Liang,
​Doreen D. Domingo, Prima Fe R. Franco, Shirley C. Agrupis, Stephen E. Stein
ABSTRACT

​Colostrum oligosaccharides are important components of milk with multifunctional health benefits to newborn children. There is an increasing interest in porcine milk because of its similarity to the milk components in human milk. However, there is a limited data on the oligosaccharide profile in porcine colostrum. The study focuses on the identification and annotation of colostrum oligosaccharides in two breeds of porcine using liquid chromatography- mass spectrometry and NIST mass spectral library search methods. One-hundred sixty-six oligosaccharides were identified and used to build a glycan mass spectral library of porcine milk. Comparing PMO (Porcine milk oligosaccharides) profile using NIST glycan library repository, 63 are found unique to porcine, 79 are oligosaccharides that shared a common structure with mature human milk and 24 are common to other mature mammalian milk. The PMO displayed different patterns of variation between black and white breeds. Of which, PMO content is highest in black breed, giving 12 unique oligosaccharides that are not found in white breed. In general, porcine milk contains both acidic (sialylated) and neutral (fucosylated) oligosaccharide, but oligosaccharides containing sialic acid predominate the PMO profile in both breeds. Among the identified oligosaccharide, pLNnH (neutral) and 3’-Sialyllactose (acidic) is the most abundant in both breeds. Colostrum from black breed has the best oligosaccharide and profile diversity. Sialylated and neutral fucosylated oligosaccharides were found to be more abundant black than the white breed. This oligosaccharides profile of black breed can be associated to the stronger immune system which gives them higher offspring survivability rate when bred in backyard farming.  

Keyword: Milk oligosaccharides, Colostrum, Porcine Milk Oligosaccharides, NIST MS search, Hybrid search
BEB-04

MICROBIAL COMMUNITY DIVERSITIES ACROSS HYPORHEIC ZONES OF GRAVEL BARS IN A RIVER: TAXONOMIC AND FUNCTIONAL DISTRIBUTIONS

Arnelyn D. DOLOIRAS- LARAÑO, Maribet GAMBOA, Shinji TAKAHASHI, Joeselle M. SERRANA,
Yasuhiro TAKEMO, Paul R. JOHNSTON, Michael T. MONAGHAN and Kozo WATANABE
ABSTRACT

​Gravel bars are geographical component in rivers and known to introduce habitat heterogeneity in river ecosystem. Among the gravel bar characteristics, the hyporheic zone, the area where surface water and groundwater meets, is known to largely affect the microbial communities. Microbial communities in gravel bars are important to the biogeochemical cycle in riverine ecosystem. In this study, we aimed to investigate the spatial distribution microbial diversities (α and β diversity) and the biological functions in three different sampling points (downwelling, upwelling and their intermediate point) within three gravel bars in the Tenryu River, Japan using 16S rRNA amplicon sequencing. The NMDS plots showed difference in bacterial community structures (β-diversity), with clear separation of three points, but the α-diversity was constant. Among the microbial organisms, the Proteobacteria were found to be the most abundant taxa throughout three points. Functional Annotation of Prokaryotic Taxa (FAPROTAX) was used to identify the potential biological function. We found the chemoheterotrophy was the most abundant function throughout the three points, suggesting the importance of primary energy metabolism for microbial community. Overall, our study highlights the changes of microbial communities’ composition among gravel bars spatial differences and future studies assessing river management.

Keyword: α-diversity, β-diversity, hyporheic zone, microbial communities, 16S rRNA amplicon sequencing
BEB-05

PURIFICATION AND CHARACTERIZATION OF ANTIOXIDANT PROTEINS FROM RICE BEAN (VIGNA UMBELLATA)

Sheryl Joyce B. Grijaldo, Marynold V. Purificacion, Paquito E. Relox, and Mary Ann O. Torio
ABSTRACT

​Higher intake of plant protein is associated with lower risk in degenerative diseases caused by oxidative stress, thereby places enormous demand in the identification of plant-based sources of protein like legumes. Rice bean (Vigna umbellata) is known to be a great source of low-cost and good nutritional quality protein for utilization in food products. This study characterized the proteins from rice bean reflecting their nutritional quality and potential as food additive. The total soluble proteins of rice bean were extracted using 50 mM Tris-HCl (pH 7.2) and 35mM potassium phosphate buffer (pH 7.2) containing 0.40 M NaCl. Major storage protein was purified using ammonium sulfate fractionation, selective precipitation and gel filtration chromatography. Pepsin digestion was done for 2 hours followed by multiple digestion of trypsin, chymotrypsin, thermolysin digests on the purified protein for 1 hour, 2 hours, and 4 hours, respectively. V. umbellata protein concentrate, hydrolysates (1 hr, 2 hrs, 4hrs), and dialysate were subjected to DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) assay to confirm antioxidant activity. V. umbellata crude protein extract and enzyme-digested protein extract provided (4-hr incubation) the highest antioxidant activity.

Keyword: Vigna umbellata, antioxidant activity, protein, hydrolysat
BEB-06

IDENTIFICATION OF NON-PEPTIDIC VENOM COMPONENTS
​OF PHILIPPINE TARANTULA SPECIES

Leonardo A. Guevarra Jr, Ralph Emerson John Molino, Anna Beatriz R. Mayor, Mark Kevin A. Devanadera, Olga M. Nuñeza, Camille Rodriguez, Myla R. Santiago-Bautista, Gardee T. Peña, and Hiyas A. Junio
ABSTRACT

​There is a growing interest in the non-peptidic components of spider venom because of the neurotoxic and cytotoxic activities of this group of compounds.  In this study, we aimed to identify the non-peptidic venom components of tarantula species collected from the Municipality of Wao in Lanao del Sur in Mindanao.    
Spider venom was extracted by electrostimulation for untargeted metabolomics analysis.  Initial separation of the components of the venom was done by reverse phase high performance liquid chromatography (RP-HPLC).  A fraction previously reported to contain non-peptidic bioactive components were further analyzed by Ultra Performance Liquid Chromatography – Quadrupole Time of Flight Data Dependent Analysis (UPLC-QTOF DDA) to structurally identify the components.
Analysis of the venom fraction resulted in the annotation of several non-peptidic components. 4-OH-PhLac343 and its isomer and isopimaric acid, palmitamide 9-octadecenamide and 13-docosenamide were putatively identified using VenoMS and GNPS, respectively. 4-OH-PhLac343, a neurotoxic acyl polyamine, was previously reported in tarantula spiders belonging to Phlogius species.  Isopimaric acid, a known plant toxin, hinted at the ability of the local spider to do detoxification and sequestration of a plant toxin to be part of its chemical arsenal.  These two compounds that have been identified interestingly may provide leads to therapeutic applications and toxin-related behavior of Philippine spider species.

Keyword: Spider, venom, toxin, Philippine tarantula, neurotoxin   ​
BEB-07

AMPALAYA (MOMORDICA CHARANTIA) AND BAYABAS (PSIDIUM GUAJAVA) EXTRACTS’ SYNERGISTIC EFFECT ON IMMORTALIZED LUNG TUMOR SPHEROIDS (GL001) VERIFIED IN RT-PCR AND IN SILICO MODELLING

Dominic Karl M. Bolinas, Mary Nicole I. Grecia, Rozel B. Razal, Michael Sigfrid S. Reyes, & Francisco M. Heralde III, RN, PhD
ABSTRACT

​In the Philippines, lung cancer is the leading cause of cancer-related deaths in males and the fourth among females. Thus, there is a need for the development of accessible and effective treatments for the disease. Momordica charantia and Psidium guajava have been found to be cytotoxic to A549 lung cancer cells, but the potential of these natural products as a source of anti-cancer bioactive components remain untapped. This study aimed to determine the synergistic effects of M. charantia and P. guajava extracts on spheroidal cultures of GL001 lung cancer cells. Through the hanging drop method, the study was able to generate spheroidal GL001cells, which provided a more appropriate representation of a tumor microenvironment in a Filipino patient-derived lung cancer cell. Furthermore, RT-qPCR analysis revealed that combinatorial extracts treatment induced upregulation of CASP8, a gene involved in Bid cleavage essential in apoptosis activation, and downregulation of MDM2, a gene involved in p53 degradation promoting tumorigenesis. This suggested that the anticancer activity of the combined extracts is through promoting apoptosis and cell cycle arrest. Verification with the in silico molecular docking analysis showed that metabolites found in ampalaya and bayabas may synergistically act by binding to specific sites in CASP8 and MDM2 protein. In particular, the synergistic binding of certain ampalaya and bayabas metabolites to CASP8 potentially stabilizes Bid-CASP8 interaction and promotes apoptosis. On the other hand, the synergistic effect of certain ampalaya and bayabas compounds on MDM2 led to either a decreased p53-MDM2 binding or a potential stabilizing effect. Both scenarios possibly disrupt p53-MDM2 interaction, preventing p53 degradation and thereby promoting cell cycle arrest. Overall, this study showed through gene expression and molecular docking analysis that M. charantia and P. guajavahave synergistic anticancer effects on lung cancer cells.

Keyword: Ampalaya, Bayabas, GL001 spheroidal cells, CASP8, MDM2, metabolites, molecular docking
BEB-08

THE DISCOVERY OF “PHILIPPINE CHERRY” SYZYGIUM LINEATUM FOR DIABETES: IN VITRO AND IN SILICO STUDIES

Franklin Ibana, Von Novi de Leon, Agnes Castillo, and Allan Patrick Macabeo
ABSTRACT

​Diabetes mellitus is growing to epidemic proportions, leading to devastating complications if left untreated. This study investigated the enzyme inhibitory activity, LC-MS analysis of the leaf extracts of S. lineatum (DC). Merr. & L.M. Perry and computational-based studies on the binding mechanisms of the putative bioactive compounds. The dichloromethane-methanol crude extract was subjected to solvent partitioning to yield petroleum ether, dichloromethane and n-butanol sub-extracts. Enzyme inhibitory assays against α-glucosidase and α-amylase were conducted. Identification of putative compounds were conducted through LC-HRMS analysis. Molecular docking was conducted to identify the best-suited receptor sites. In the α-glucosidase inhibitory assay, the n-butanol sub-extract ofS. lineatum displayed an IC50 value of 48.31 ± 0.890 ug/mL whereas, the crude extract has shown an IC50 value of 13.60 ± 0.050 ug/mL in the α–amylase inhibition assay. LC-HRMS analysis of the crude and n-butanol sub-extract yielded staphylionoside J (1), quercetin-3-glucoside (2), myricetin (3), quercitrin (4), kaempferol-3-rhamnoside (5), arjunolic acid (6) and asiatic acid (7). Molecular docking studies revealed strong binding affinities (ca. -9 kJ/mol) on the catalytic site of a-glucosidase for the flavonoids myricetin (3), quercitrin (4), kaempferol-3-rhamnoside (5). Thus, the plant derived bioactive compounds contribute to the inhibition of the enzymes in the in vitro assays complimented by in silico experiments. This is a pioneering study of S. lineatum leaf extracts which presents potential benefits on inhibition of intestinal enzymes.

Keyword: Syzygium lineatum, α-glucosidase, α-amylase, diabetes, euglycemi
BEB-09

SUITABILITY OF ITS2, NAD1 AND YCF1B AS DNA BARCODES FOR THE TEN MEDICINAL PLANTS OF THE PHILIPPINES

Levi Letlet H. Larcia II, Joseph Christian M. Manzano, Kyle Maleen O. Sagulili, Jerica Margarita G. Ibanez, Ciara Christianne Y. Lim, Joanne Marie M. Del Rosario, Paul Benedic U. Salvador, Laarni G. Corales and Leslie Michelle
M. Dalmacio
ABSTRACT

​The Department of Health had listed ten herbal medicines commonly used in the Philippines for different ailments referred to as “Sampung Halamang Gamot” or 10HG1. Ensuring proper identification of these herbal medicines is important to prevent numerous adverse reactions. DNA barcoding, a taxonomic method that uses a short genetic marker in an organism's DNA to identify it as belonging to a particular species2, can be used to augment the current methods of identification.  ITS2, nad1 and ycf1b are three of the most commonly used genetic loci for DNA barcoding3,4.   
 
This study determined the suitability of these genetic markers as DNA barcodes for the identification of 10HG by comparing their PCR success rate, sequence quality, and discriminatory power.  For PCR success rate, the 10 HG gave 100%, 80% and 40% amplification using ITS2, ycf1b and nad1, respectively. With regard to the sequence quality, high quality sequences were given by A. sativum, P.guajava, Q. indica, and E.microphylla using ITS2 while high quality sequences were given by C. alata, M. charantia, P. guajava, V. negundo, and Q. indica  using ycf1b. Finally, for the discriminatory power, six out of the 10 HG gave species level discrimination using ITS2 and two out of the ten for ycf1b. Nad1 data for sequence quality and discriminatory power was inconclusive. 
 
From the data gathered, it can be inferred that ITS2 is the most suitable DNA barcode for the 10HG. The utilization of ITS2 as a standard DNA barcode for 10HG is supported by the study of Chen et al.5 wherein they concluded that the ITS2 region can be potentially used as a standard DNA barcode to identify medicinal plants and their closely related species. For the suitability of nad1 and ycf1b as 10HG DNA barcodes, however, further studies are recommended to make a conclusion. 

Keyword: DNA Barcoding, ITS2, nad1, ycf1b, Medicinal plants
BEB-10

TRICHODERMA REESEI RAD51 TOLERATES MISMATCHES IN HYBRID MEIOSIS WITH DIVERSE GENOME SEQUENCES

Wan-Chen Li, Chia-Yi Lee, Wei-Hsuan Lan, Tai-Ting Woo, Hou-Cheng Liu, Hsin-Yi Yeh, Hao-Yen Chang, Yu- Chien Chuang, Chiung-Ya Chen, Chi-Ning Chuang, Chia-Ling Chen, Yi-Ping Hsueh, Hung-Wen Li, and Peter Chi and Ting-Fang Wang
ABSTRACT

​Most eukaryotes possess two RecA-like recombinases (ubiquitous Rad51 and meiosis-specific Dmc1) to promote interhomolog recombination during meiosis. However, some eukaryotes have lost Dmc1. Given that mammalian and yeast S. cerevisiae (Sc) Dmc1 have been shown to stabilize resombination intermediates containing mismatches better than Rad51, we used the Pezizomycotina filamentous fungus Trichoderma reesei to address if and how Rad51-only eukaryotes conduct interhomolog recombination in zygotes with high sequence heterogeneity. We applied multidisciplinary approaches (next- and third-generation sequencing technology, genetics, cytology, bioinformatics, biochemistry and single-molecule biophysics) to show that T. reesei Rad51 (TrRad51) is indispensable for interhomolog recombination during meiosis and, like ScDmc1, TrRad51 possesses better mismatch tolerance than ScRad51 during homologous recombination. Our results also indicate that the ancestral TrRad51 evolved to acquire ScDmc1-like properties by creating multiple structural variations, including via amino acid residues in the L1 and L2 DNA-binding loops.
BEB-11

SCREENING AND IDENTIFICATION OF ALKALIPHILIC BACTERIA PRODUCING CYCLODEXTRIN GLUCANOTRANSFERASE AND PROTEASES FROM MANLELUAG HYPERALKALINE SPRING

Eula Francia M. Bosito, Aprill P. Manalang, Noel G. Sabino, Rose Ann G. Franco, Ma. Genaleen Q. Diaz,
​Andrew D. Montecillo, and Nacita B. Lantican
ABSTRACT

​Manleluag hyperalkaline spring is a unique spring in Pangasinan, Philippines.  In this study, alkaliphilic bacteria were screened for the presence of industrially important enzymes – cyclodextrin glucanotransferase (CGTase) and proteases. From a total of 826 bacterial isolates, 54 isolates exhibited significant CGTase production evaluated using the Phenolphthalein Assay. The highest recorded CGTase activity is at 46.01 U/ml. Using two pH conditions (pH 7 and pH 10), 428 isolates showed protease activity when tested using Skim Milk Assay with an activity reaching up to a clearing zone ratio of 0.2056. Based on whole-genome sequence assemblies, the top CGTase producer was found to be a Bacillus lehensis isolate while the top protease producer was a putative Bacillus gibsonii isolate. Hence, this study showed that the Manleluag hyperalkaline spring served as a good source of alkaliphilic bacteria producing industrially important compounds.

Keywords: Manleluag hyperalkaline spring, alkaliphilic bacteria, protease, cyclodextrin glucanotransferase
BEB-12

NOVEL BIOSYNTHETIC SYSTEM FOR UNRAVELING CONIDIOGENONES BIOSYNTHESIS IN PENICILLIUM SP. F23-2

John David P. Pilapil, Mariam C. Recuenco, Marilyn O. Quimado, and Maribel L. Dionisio-Sese
ABSTRACT

​Penicillium sp. F23-2 is a deep-sea fungus that offers a wide range of ecological, medicinal, and commercial value. This microbe produces unique tetracyclic diterpenes belonging to the cyclopiane class of natural products. Among these are conidiogenones and related bioactive compounds that exhibit chemopreventive activity against human leukemia cells and potent inhibitory properties against methicillin-resistant Pseudomonas and Staphylococcusspecies. While the potential of conidigenones and its derivatives as promising natural antibiotics and antitumor drugs has been recognized, the mechanism of conidiogenone biosynthesis and its associated enzymes remain unclear. In this study, a biosynthetic pathway for the production of conidiogenone derivatives and other alkaloid terpene hybrid compounds was proposed through the discovery of a dual-function terpene synthase (Con-TC). This chimeric enzyme, which comprised of an N-terminal terpene synthase domain and a C-terminal prenyltransferase, used dimethylallyl pyrophosphate (DMAPP) and isopentenyl pyrophosphate (IPP) as substrates to produce cyclopiane compounds. The function of Con-TC was verified by heterologous expression in Aspergillus oryzae, which led to the production of the tetracyclic core skeleton. Con-TC and a cytochrome P450 oxygenase (Con-OXY) were collectively coexpressed resulting to the production of conidiogenone B. Reconstitution and coexpression of tailoring enzymes encoded on the gene cluster showed the production of conidiogenone derivatives. Moreover, supplementation of meleagrin to this heterologous system caused the accumulation of terpene-alkaloid hybrid intermediates. This study proposes that the characterized enzymes in this study can be utilized as valuable biocatalysts to generate new bioactive conidiogenone derivatives.

Keywords: bioactive natural products, biosynthetic pathway, genetic engineering, microbial transformation, secondary metabolites
BEB-13

BIOSYNTHETIC MACHINERIES INFLUENCE STRAIN-LEVEL ANTIBIOTIC VARIATION IN MULTIPLE STREPTOMYCES SPECIES FROM PHILIPPINE MARINE SEDIMENTS

Carmela Vannette Vicera, Chuckcris Tenebro, Dana Joanne Von Trono, Jovito Ysulat, Jr.,
​Aaron Joseph Macaspac, Jonel Saludes, and Doralyn Dalisay
ABSTRACT

​The genus Streptomyces are exceptional microbial cell factories known to produce a wide array of chemical metabolites. These secondary metabolites are produced by machineries encoded in an organized group of genes called biosynthetic gene clusters (BGCs), and the potential of Streptomyces to produce diverse bioactive metabolites relies on its large number of BGCs. Majority of the total BGCs in Streptomyces are the non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) pathways which produce antimicrobials such as vancomycin and cycloheximide. Here, we report the variation in antibiotic activity and biosynthetic gene clusters of multiple Streptomyces species and closely related strains from Philippine marine sediments. A total of 2,780 actinobacteria were isolated and tested for their antibacterial activity against a multidrug resistant bacterium (Staphylococcus aureusATCC BAA-44) and three Gram-negative pathogenic bacteria (Escherichia coli ATCC 25922, Enterobacter aerogenesATCC 13048, and Pseudomonas aeruginosa ATCC 27853). Out of the 2,780 isolates, 134 strains were observed to exhibit antibiotic activity. The 16S rRNA gene sequence analysis revealed that the isolates were identical to Streptomyces species. Differences in the magnitude of antibiotic activity and sensitivity against the test pathogens were seen among closely related strains of Streptomyces species such as the S. parvulus and S. rochei, suggesting that antibiotic production differs at species strain-level. Amplification of BGCs showed that all bioactive species harbors NRPS gene and interspecies variation was seen in their PKS Type I and Type II domains. However, four Streptomyces species, S. rochei, S. enissocaesilis, S. geysiriensis, and S. mutabilis demonstrated intraspecies variation on their PKS-II KSα and KSβ domain complexes, which showed correlation with their antibiotic activities. These findings in the strain-level bioactivity variation and biosynthetic gene detection reveal an important clue that helps reinvigorate the discovery of new antibiotics from Streptomyces.

Keywords: biosynthetic gene clusters, antibiotic, marine sediments, Streptomyces, multidrug resistant pathogen