Tropical Peatland Hydrology Simulated With a Global Land Surface Model

Tropical peatlands are among the most carbon-dense ecosystems on Earth, and their water storage dynamics strongly control these carbon stocks. The hydrological functioning of tropical peatlands differs from that of northern peatlands, which has not yet been accounted for in global land surface models (LSMs). Here, we integrated tropical peat-specific hydrology modules into a global LSM for the first time, by utilizing the peatland-specific model structure adaptation (PEATCLSM) of the NASA Catchment Land Surface Model (CLSM). We developed literature-based parameter sets for natural (PEATCLSM_Trop,Nat) and drained (PEATCLSM_Trop,Drain) tropical peatlands. Simulations with PEATCLSM_Trop,Nat were compared against those with the default CLSM version and the northern version of PEATCLSM (PEATCLSM_North,Nat) with tropical vegetation input. All simulations were forced with global meteorological reanalysis input data for the major tropical peatland regions in Central and South America, the Congo Basin, and Southeast Asia. The evaluation against a unique and extensive data set of in situ water level and eddy covariance-derived evapotranspiration showed an overall improvement in bias and correlation compared to the default CLSM version. Over Southeast Asia, an additional simulation with PEATCLSM_Trop,Drain was run to address the large fraction of drained tropical peatlands in this region. PEATCLSM_Trop,Drain outperformed CLSM, PEATCLSM_North,Nat, and PEATCLSM_Trop,Nat over drained sites. Despite the overall improvements of PEATCLSM_Trop,Nat over CLSM, there are strong differences in performance between the three study regions. We attribute these performance differences to regional differences in accuracy of meteorological forcing data, and differences in peatland hydrologic response that are not yet captured by our model.

Saturnispora kantuleensis f.a., sp. nov., a novel yeast species isolated from peat in a tropical peat swamp forest in Thailand

Two strains (DMKU-PPS4-5^T and DMKU-EPS3-4) representing a single novel anamorphic yeast species were isolated from two peat samples collected in Kan Tulee peat swamp forest, Surat Thani Province, Thailand. The strains differed by two nucleotide substitutions in the sequences of the D1/D2 region of the large subunit (LSU) rRNA gene and only one nucleotide substitution in the internal transcribed spacer (ITS) region. Phylogenetic analysis based on the D1/D2 regions showed that the two strains represented a single species in the genus Saturnispora and were clearly distinct from other related species. Saturnispora sekii was the most closely related species, but with 1.7-2.1 % nucleotide substitutions in the D1/D2 region of the LSU rRNA gene, and 3.1-3.3 % nucleotide substitutions in the ITS region. They therefore represent a novel species of the genus Saturnispora, although the formation of ascospores was not observed. The name Saturnispora kantuleensis f.a., sp. nov. is proposed. The type strain is DMKU-PPS4-5^T (=CBS 15217^T=TBRC 7762^T).

Newly Isolated Paenibacillus tyrfis sp. nov., from Malaysian Tropical Peat Swamp Soil with Broad Spectrum Antimicrobial Activity

Emergence of antimicrobial resistance coupled with the slowdown in discovery of new antimicrobial compounds points to serious consequences for human health. Therefore, scientists are looking for new antimicrobial compounds from unique and understudied ecosystems such as tropical peat swamp forests. Over the course of isolating antimicrobial producing bacteria from North Selangor tropical peat swamp forest, Malaysia, a Gram variable, rod shaped, endospore forming, facultative anaerobic novel strain MSt1^T that exerts potent and broad spectrum antimicrobial activity was isolated. Phylogenetic analysis using 16S rRNA gene sequences showed that strain MSt1^T belonged to the genus Paenibacillus with the highest similarity to Paenibacillus elgii SD17^T (99.5%). Whole genome comparison between strain MSt1^T with its closely related species using average nucleotide identity (ANI) revealed that similarity between strain MSt1^T with P. elgii B69 (93.45%) and Paenibacillus ehimensis A2 (90.42%) was below the recommended threshold of 95%. Further analysis using in silico pairwise DDH also showed that similarity between strain MSt1^T with P. elgii B69 (55.4%) and P. ehimensis A2 (43.7%) was below the recommended threshold of 70%. Strain MSt1^T contained meso-diaminopilemic acid in the cell wall and MK-7 as the major menaquinone. The major fatty acids of strain MSt1^T were anteiso-C_15:0 (48.2%) and C_16:0 (29.0%) whereas the polar lipid profile consisted of phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, one unknown lipid, two unknown glycolipids, and one unknown phospholipid. Total DNA G+C content of strain MSt1^T was 51.5 mol%. The extract from strain MSt1^T exerted strong antimicrobial activity against Escherichia coli ATCC 25922 (MIC = 1.5 μg/mL), MRSA ATCC 700699 (MIC = 25 μg/mL) and Candida albicans IMR (MIC = 12.5 μg/mL). Partially purified active fraction exerted a strong effect against E. coli ATCC 25922 resulting in cell rupture when viewed with SEM. Based on distinctive taxonomic differences between strain MSt1^T when compared to its closely related type species, we propose that strain MSt1^T represents a novel species within the genus of Paenibacillus, for which the name Paenibacillus tyrfis sp. nov. (= DSM 100708^T = MCCC 1K01247^T) is proposed.