The Integrated Effect of Microbial Inoculants and Biochar Types on Soil Biological Properties, and Plant Growth of Lettuce (Lactuca sativa L.)

Numerous reports confirm the positive effect of biochar application on soil properties and plant development. However, the interaction between root-associated beneficial microbes and different types of biochar is not well understood. The objective of this study was to evaluate the plant growth of lettuce after the application of three types of biochar in loamy, sandy soil individually and in combination with plant-beneficial microbes. Furthermore, total microbial activity in rhizosphere soil of lettuce was measured by means of fluorescein diacetate (FDA) hydrolase and enzyme activities linked to carbon, nitrogen, and phosphorus cycling. We used three types of biochar: (i) pyrolysis char from cherry wood (CWBC), (ii) pyrolysis char from wood (WBC), and (iii) pyrolysis char from maize (MBC) at 2% concentration. Our results showed that pyrolysis biochars positively affected plant interaction with microbial inoculants. Plant dry biomass grown on soil amended with MBC in combination with Klebsiella sp. BS13 and Klebsiella sp. BS13 + Talaromyces purpureogenus BS16aPP inoculants was significantly increased by 5.8% and 18%, respectively, compared to the control plants. Comprehensively, interaction analysis showed that the biochar effect on soil enzyme activities involved in N and P cycling depends on the type of microbial inoculant. Microbial strains exhibited plant growth-promoting traits, including the production of indole 3-acetic-acid and hydrogen cyanide and phosphate-solubilizing ability. The effect of microbial inoculant also depends on the biochar type. In summary, these findings provide new insights into the understanding of the interactions between biochar and microbial inoculants, which may affect lettuce growth and development.Peer Reviewe

“Pick-up Lines”: A Fun Way to Facilitate Learning Microbiological Concepts

<p>Learning microbiology can be made fun by writing funny lines related to microbiology. Students were tasked to create their own pick-up lines and explain these based on their understanding of the basic concepts in microbiology.</p

Microbes for sustainable agriculture: Isolation and identification of beneficial soil- and plant-associated microorganisms

In soil, fungi are effective in the control of pathogens while bacteria can promote growth of plants through secretion of growth-promoting hormones. In this study, beneficial fungi and bacteria were isolated from bulk and rhizosphere soil samples, and from leaves, stems, and roots of romaine lettuce (Lactuca sativa L. var. longifolia) either as epiphytes or endophytes. The isolated microorganisms were tested for their ability to solubilize phosphate. Given the low amount of phosphorus in soil, the ability to acquire this mineral from the soil and share it with its host plants is an important trait that can enhance plant growth. From this study, one bacterium and seven fungal strains were capable of doing this task as evidenced by the clearing zones around colonies in Pikovskayas agar. Isolated soil- and plant-associated fungi were also tested for their ability to inhibit the growth of a plant pathogenic fungus. The dual-culture setups showed 30 of the 53 fungal strains exhibiting antagonistic activities. Of these, nine fungi positively inhibited the growth of Fusarium oxysporum. Identities of the beneficial microorganisms were confirmed through gene sequence analysis. This study showed the potential of soil- and plant- associated microorganisms as plant growth enhancer that can possibly be incorporated in soil amendments

Isolation and Characterization of Nickel-Tolerant Trichoderma Strains from Marine and Terrestrial Environments

Nickel contamination is a serious environmental issue that requires immediate action. In this study, 23 strains of Trichoderma were isolated from terrestrial and marine environments and identified using a polyphasic approach of morphological characterization and ITS gene sequence analysis. The Trichoderma strains were tested for their tolerance and biosorption of nickel. Our results showed the growth of all Trichoderma strains on Trichoderma Selective Medium (TSM) with 50–1200-ppm nickel, indicating their tolerance of this heavy metal even at a relatively high concentration. Six Trichoderma strains (three isolated from terrestrial substrates and three from marine substates) had the highest radial growth on TSM with 50-ppm Ni. Among these fungal isolates, Trichoderma asperellum (S03) isolated from soil exhibited the best growth after 2 days of incubation. For the biosorption of nickel, the accumulation or uptake efficiency by the six selected Trichoderma was determined in Potato Dextrose Broth (PDB) supplemented with 50-ppm Ni using a Flame Atomic Absorption Spectrophotometer (AAS). The percent uptake efficiency of the three strains of T. asperellum (S03, S08, and LL14) was computed to be up to 66%, while Trichoderma virens (SG18 and SF22) and Trichoderma inhamatum (MW25) achieved up to 68% uptake efficiency. Observation of the Trichoderma strains with Scanning Electron Microscopy (SEM) before and after the absorption of nickel showed very minimal damage on the hyphal and conidial surface morphology, but changes in the colonial characteristics were observed. Our study highlighted the potential of terrestrial and marine strains of Trichoderma for the bioremediation of nickel pollution

DIVERSITY AND DISTRIBUTION OF PLASMODIAL MYXOMYCETES (SLIME MOLDS) FROM LA MESA ECOPARK, QUEZON CITY, PHILIPPINES

Myxomycetes are ubiquitous in terrestrial forest ecosystems. Thus, this research study looks at the taxonomic diversity and distribution of plasmodial myxomycetes in La Mesa Ecopark in Quezon City, Philippines. A total of 240 moist chambers were prepared from four substrates (aerial and ground leaf litter, twigs and barks) collected within this ecopark. Following incubation of moist chambers for eight weeks, a total of 28 species belonging to 10 genera were collected and identified: Arcyria (3), Diderma (2), Didymium (5), Lamproderma (2), Perichaena (3), Physarum (8), Macbrideola (1), Metatrichia (1), Trichia (1) and Stemonitis (2). Highest myxomycete yield (85%) was observed in aerial leaf litter. In terms of taxonomic diversity, highest diversity was observed in bark microhabitats, although the lowest number of species was recorded in it. Assessment of their abundance and distribution showed similarities in species composition between aerial and ground leaf litter. This research study is the first report of plasmodial myxomycetes in La Mesa Ecopark in Quezon City, Philippines

ANTIMICROBIAL AND HERBICIDAL PROPERTIES OF THE FRUTICOSE LICHEN Ramalina FROM GUIMARAS ISLAND, PHILIPPINES

Lichens, a unique symbiosis between a mycobiont and a photobiont organism, are known to produce metabolites that can be tapped as biopesticides for agriculture. Such property of the fruticose lichen Ramalina collected within Guimaras Island, Philippines was investigated in this study. A total of 195 specimens were collected and characterized using conventional morphological and chemical analyses. These lichens were identified as Ramalina farinacea, R. roesleri, and R. nervulosa. To test their potential application in agriculture, nine lichen specimens were extracted with acetone and assayed for its inhibitory activities against test bacteria, fungi, and weedy plants. All nine lichen extracts inhibited Pseudomonas aeruginosa (&gt;19 mm ZOI) while only seven lichen extracts inhibited Staphylococcus aureus (13–19 mm ZOI). No inhibitory activity was observed among the fungal plant pathogens Fusarium oxysporum, F. solani, F. verticillioides, Colletotrichum capsici, and C. gleosporioides, and on the Gram-negative bacteria Escherichia coli and Pectobacterium carotovorum var. carotovorum. A decrease in the root (up to 27% reduction) and shoot (up to 39% reduction) lengths, and leaf chlorophyll content (up to 44% reduction) of rice weeds Fimbristylis miliacea, Leptochloa chinensis and weedy rice (Oryza sp.) were also observed. These results, therefore, suggested that the lichen crude extract from Ramalina is a potential biological control for weed management

Diversity, Phylogeny and Antagonistic Activity of Fungal Endophytes Associated with Endemic Species of Cycas (Cycadales) in China

The culture-based approach was used to characterize the fungal endophytes associated with the coralloid roots of the endemic Cycas debaoensis and Cycas fairylakea from various population sites in China. We aim to determine if the assemblages of fungal endophytes inside these endemic plant hosts are distinct and could be explored for bioprospecting. The isolation method yielded a total of 284 culturable fungal strains. Identification based on the analysis of the internal transcribed spacer (ITS) rDNA showed that they belonged to two phyla, five classes, eight orders and 22 families. At least 33 known genera and 62 different species were confirmed based on &gt;97% ITS sequence similarity. The most frequent and observed core taxa in the two host species regardless of their population origin were Talaromyces, Penicillium, Fusarium, Pochonia and Gliocladiopsis. Seventy percent was a rare component of the fungal communities with only one or two recorded isolates. Contrary to common notions, diversity and fungal richness were significantly higher in C. debaoensis and C. fairylakea collected from a botanical garden, while the lowest was observed in C. debaoensis from a natural habitat; this provides evidence that garden management, and to a minor extent, ex-situ conservation practice, could influence fungal endophyte communities. We further selected nineteen fungal isolates and screened for their antagonistic activities via a co-cultivation approach against the phytopathogens, Diaporthe sp. and Colletotrichum sp. Among these, five isolates with high ITS similarity matches with Hypoxylon vinosupulvinatum (GD019, 99.61%), Penicillium sp. (BD022, 100%), Penicillifer diparietisporus (GD008, 99.46%), Clonostachys rogersoniana (BF024, 99.46%) and C. rosea (BF011, 99.1%), which showed exceptional antagonistic activities against the phytopathogenic fungi with a significant inhibition rate of 70–80%. Taken together, our data presented the first and most comprehensive molecular work on culturable fungal endophytes associated with the coralloid roots of cycads. Our study also demonstrated that about 5% of fungal endophytes were not detected by the high-throughput sequencing approach, implying the equal importance of a culture-dependent approach to study fungal communities of cycads. We further highlighted the potential role of endemic and rare plants to discover and isolate unique plant-associated fungal taxa with excellent biocontrol properties

Comparative Study on the Antimicrobial Activities and Metabolic Profiles of Five <i>Usnea</i> Species from the Philippines

The rapid emergence of resistant bacteria is occurring worldwide, endangering the efficacy of antibiotics. Hence, there is a need to search for new sources of antibiotics that either exhibit novel structures or express a new mechanism of action. The lichen Usnea, with its wide range of unique, biologically potent secondary metabolites, may solve this problem. In this study, Usnea species were collected in the Northern Philippines, identified through combined morphological and biochemical characterization, and tested for antimicrobial activities against the multidrug-resistant ESKAPE pathogens, i.e., Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter cloacae, two standard antibiotic-sensitive test bacteria, and a yeast. A total of 46 lichen specimens were collected and later identified as Usnea baileyi (10), U. diffracta (10), U. glabrata (12), U. longissima (4), and U. rubicunda (10). The results show that the crude extracts of the Usnea species exhibited promising in vitro inhibitory activities against standard antibiotic-sensitive (E. faecalis ATCC 29212) and multidrug-resistant (methicillin-resistant S. aureus and E. faecalis) Gram-positive bacteria. Additionally, lichen compounds of representative specimens per species were identified and profiled using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). The detection of lichen acids (LA) via HPLC showed the presence of 24 peaks of lichen acids. TLC-bioautography identified the bioactive lichen acids as alectronic acid, connorstictic acid, consalazinic acid, diffractaic acid, echinocarpic acid, erythrin acid, galbinic acid, hypoconstictic acid, hyposalazinic acid, hypostictic acid, lobaric acid, menegazzaic acid, micareic acid, pannarin, salazinic acid, stictic acid, and usnic acid. Our study highlighted the wide spectrum of opportunities for using lichens for the discovery of potential antimicrobial agents