Fungi in sediments of the sea of Japan and their biologically active metabolites

The most abundant marine fungi encountered in various regions of the Sea of Japan belong to the generaPenicillium, Aspergillus, Wardomyces, Trichoderma, Chrysosporium, andChaetomium. Facultative marine fungi of the generaScytalidium, Verticillium, andOidiodendron and obligate marine fungi of the genusDendryphiella are much less abundant. The composition of marine sediments and the anthropogenic load on them were found to influence the abundance and species diversity of fungi, as well as the occurrence of fungal strains producing hemolytically active substances. The biodiversity of mycobiota and the abundance of hemotoxin-producing fungi in marine sediments may be used to evaluate the anthropogenic load on marine biocenoses. Hemolytic compounds were produced by 57% of the fungi isolated from marine sediments. The hemolytic activity ofChaetomium spiculipilium was revealed in the fraction of the culture liquid containing extracellular fatty acids and pigments. The fatty acid composition of this marine fungus was determined.     

Spatio-temporal,environmental factors,and host identity shape culturable-epibiotic fungi of seaweeds in the Red Sea,Egypt

The study of fungal species diversity from marine algae is in its infancy; as now no studies have been carried out on the distribution and diversity of fungi on the surfaces of marine macroalgae where all fungal–algal interactions tend to begin. The aim of this study was to isolate and describe the culturable part of mycobiota associated with the surface of benthic marine macroalgae (epiphytic or epibiotic fungi). This is an important step in understanding their abundance, diversity and factors influencing their variability and composition. The fungal community was dominated by Ascomycetes (89%) with Eurotiales as the most abundant fungal order followed by Capnodiales, Pleosporales, and Hypocreales, while Zygomycetes was less frequent. The nature of occurrence of fungal genera on different macroalgal hosts suggests that a mix of generalists’ framework applies to fungal epiphytes of seaweeds, but the abundance of fungal taxa varied among ecological functional groups of algae, as well as macroalgal taxonomic groups, which imply host filtering. The fungal assemblages were also characterized by temporal variation with variation in temperature, pH, and salinity as the most important abiotic factors. The structure of fungal assemblages showed high beta diversity and low similarity between hosts.     

南海冷泉区深海沉积物中细菌的分离培养及多样性分析

为了认识南海深海冷泉区沉积物中可培养微生物的多样性,本文以冷泉区与非冷泉区两个站点的深海沉积物为样品,通过两种培养基(R2A海水培养基和2216E培养基)直接涂布或富集后平板分离纯化,从9个样品中共得到395株菌株,并通过16SrRNA基因鉴定,分属10个属。发现产芽胞细菌分布最广、丰度最大,包括3个属、15个种。其中芽胞杆菌(Bacillus)无论是在数量还是在种类上都分布最多。并且,随着水深和沉积物深度的增加,分离到的可培养微生物丰富度降低。本研究表明,即使在冷泉区,南海深海沉积物中产芽胞细菌也比较丰富。     

High contents of 24:6(n-3) and 20:1(n-13) fatty acids in the brittle star Amphiura elandiformis from Tasmanian coastal sediments

The presence of long-chain polyunsaturated fatty acids (PUFA; ca. 9% of total fatty acids) in marine sediments near Dover, southern Tasmania, Australia prompted a search for their likely source. Analysis of a number of different species of benthic fauna isolated from these sediments revealed that the brittle star Amphiura elandiformis contained abundant PUFA including high contents of the uncommon long-chain fatty acid 24:6(n-3), but much smaller amounts of the more common animal PUFA 22:6(n-3). This is the first report of the lipid composition of this animal. Identifications of the unsaturated fatty acids were confirmed by formation of DMOX derivatives which gave characteristic and easily interpreted mass spectra. The 24:6(n-3) PUFA has been identified in some genera of brittle stars, but not others. It is rarely found in significant amounts in other marine animals. DMDS adducts were used to identify the positions of double bonds in the monounsaturated fatty acids. The major 20:1 isomer was identified as the rarely reported 20:1(n-13) fatty acid. The two fatty acids 20:1(n-13) and 24:6(n-3) may be useful biomarkers in food-web studies for identifying a brittle star diet and for recognising contributions of organic detritus from this benthic animal to marine sediments.     

Filamentous fungi associated with holothurians from the sea of Japan, off the primorye coast of Russia

Holothurians (Holothurioidea, Echinodermata) are known to contain triterpene glycosides, which show antifungal activity. Nevertheless, fungi can be isolated from all organs of holothurians. During 1995-1996, mycelial fungi from several Far-Eastern holothurians--Apostichopus japonicus, Eupentacta fraudatrix, Cucumaria japonica--were collected from the Sea of Japan near the coast of Primorye (Russia) and studied. Twenty-seven species of marine fungi, mostly facultative ones belonging to the mitosporic fungi, were isolated from the holothurians and identified. Fungi isolated from the holothurian surface were more diverse and abundant than those from internal organs and coelomic fluids. Of the holothurians studied, Cucumaria japonica was poorest in abundance and diversity of fungi. The fungi Cladosporium brevicompactum and C. sphaerospermum were common in the holothurian coelom. Because of their high proteolytic activity, these fungi may be pathogenic to holothurians. The detritovorus holothurian A. japonicus was shown to modify the fungal assemblages within the marine bottom sediments.     

Contrasting distributions of bacteriophages and eukaryotic viruses from contaminated coastal sediments

Viruses are ubiquitous, abundant and play an important role in all ecosystems. Here, we advance understanding of coastal sediment viruses by exploring links in the composition and abundance of sediment viromes to environmental stressors and sediment bacterial communities. We collected sediment from contaminated and reference sites in Sydney Harbour and used metagenomics to analyse viral community composition. The proportion of phages at contaminated sites was significantly greater than phages at reference sites, whereas eukaryotic viruses were relatively more abundant at reference sites. We observed shifts in viral and bacterial composition between contaminated and reference sites of a similar magnitude. Models based on sediment characteristics revealed that total organic carbon in the sediments explained most of the environmental stress-related variation in the viral dataset. Our results suggest that the presence of anthropogenic contaminants in coastal sediments could be influencing viral community composition with potential consequences for associated hosts and the environment.     

蒙古栎根内及根围土壤中共生真菌和细菌群落组成分析

为探究中国东北地区森林根系和根围土壤中共生真菌的分布状况,分析了黑龙江省五大连池市蒙古栎Quercus mongolica纯林中根内及根围土壤中共生真菌和细菌群落的组成。结果表明,根内真菌的1 295个OTUs中有209个OTUs为共生真菌,隶属于36属,相对丰度25.46%;根围土壤真菌1 513个OTUs中有285个OTUs为共生真菌,隶属于40属,相对丰度59.91%;根内与根围土壤共同拥有共生真菌33属,根内特有3属,根围土壤特有7属。其中,外生菌根真菌为根内和根围土壤中共生真菌的主要类群,分别占共生真菌的98.82%和99.80%。定殖根内的细菌共获得5 550个OTUs,隶属于400属;根围土壤细菌获得8 406个OTUs,隶属于436属,根内细菌群落的Shannon指数和Chao1指数均低于根围土壤的。PICRUSt功能预测分析结果表明,根内的信号转导通路与信号分子和相互作用通路（包括CAM配体、ECM-受体相互作用等通路）的丰度低于根围土壤,而膜运输通路与信号分子和相互作用通路（包括细菌毒素、细胞抗原等通路）的丰度高于根围土壤。根内与根围土壤中菌根辅助细菌组成差异分析结果表明,除慢生根瘤菌属 Bradyrhizobium外,根内其余9属的相对丰度均高于根围土壤,尤其假单胞菌属 Pseudomonas的相对丰度远高于根围土壤。     

北京夏植黄瓜内生真菌区系研究

为了解黄瓜植株内生真菌的区系组成及其变化,从而为进一步研究黄瓜内生真菌的生态和功能奠定基础,对采自北京延庆的不同品种和不同生育期的40株黄瓜进行了内生真菌的分离培养。经形态学鉴定和18S rDNA序列分析,分离到的1,024株内生真菌属于18属,其中Exserohilum和Neocosmospora尚未见内生真菌的报道。Alternaria、Aspergillus、Chaetomium、Cladosporium和Fusarium在各生育期和各器官普遍存在。其中,Alternaria在叶中的定殖率达47.0%,远高于在其他器官中的定殖率;Fusarium在根中的定殖率达32.5%,远高于在其他器官中的定殖率。多数真菌类群表现出不同程度的器官偏好性,有些真菌类群则只出现在特定器官中。叶和根的内生真菌类群数量和总定殖率均高于茎和果实。随着黄瓜的生长,各器官内生真菌的类群数在增加,部分真菌的定殖率也呈上升趋势,但Neocosmospora和Chaetomium在各器官中的定殖率则随植株生长呈下降趋势。     

Microbial diversity in tropical marine sediments assessed using culture-dependent and culture-independent techniques

The microbial communities associated with marine sediments are critical for ecosystem function yet remain poorly characterized. While culture-independent (CI) techniques capture the broadest perspective on community composition, culture-dependent (CD) methods can select for low abundance taxa that are missed using CI approaches. This study aimed to assess microbial diversity in tropical marine sediments at five shallow-water sites in Belize using both CD and CI techniques. The CD methods captured approximately 3% of the >800 genera detected across all sites using the CI approach. Additionally, 39 genera were only detected in culture, revealing rare taxa that were missed with the CI approach. Significantly different communities were detected across sites, with rare taxa playing an important role in distinguishing among communities. This study provides important baseline data describing shallow-water sediment microbial communities, evidence that standard cultivation techniques may be more effective than previously recognized, and the first steps towards identifying new taxa that are amenable to agar plate cultivation.     

Seed lipids of the lythraceae

Fatty acid composition of seed lipids for 20 of the 26 genera in the Lythraceae and seed oil and protein content for nine genera are reported. The percent oil ranges from 2.7 to 34% of total weight and protein from 11.3 to 24.9%. Linoleic acid is the dominant fatty acid in seed lipids of all genera surveyed. Variations in pattern emphasize palmitic or oleic acid or both as second most abundant lipid component. There are three exceptions: in Diplusodon capric acid ranks second in abundance; in Adenaria lauric acid and oleic acid occur in approximately equal amounts as second most abundant fatty acid; in Decodon an unusual trienoic acid, previously reported only from the Compositae, is the main secondary component. Fatty acid composition of seeds in the genera is compared to that of the previously studied lythraceous genus Cuphea. Among all the genera, only Cuphea seed produces large quantities of lauric, capric, or caprylic acids, as well as a diversity of fatty acid patterns. No relationship between oil content or seed weight and habit is apparent in any genus studied, nor are differences in seed morphology reflected in composition of the seed lipids. The fatty acid patterns are judged evolutionarily conservative, with the strong exception of Cuphea, which remains unique in the Lythraceae and among all angiosperms for the diversity of patterns displayed.     

Effects of fungal food quality and starvation on the fatty acid composition of Protaphorura fimata (Collembola)

The lipid pattern of animals is influenced by species, life stage, environmental conditions and diet. We investigated the effects of food quality and starvation on the phospholipid (PLFA) and neutral lipid (NLFA) fatty acid pattern of the collembolan Protaphorura fimata. Collembolans were fed with two common soil fungi, Agrocybe gibberosa and Chaetomium globosum, of which the cellular lipid composition was analysed. A. gibberosa was grown on agar with different nitrogen contents, resulting in altered fatty acid patterns and C:N ratios, i.e. fungi of different food quality. Collembolans did not mirror the lipid composition of the fungal diet as the pattern of major NLFAs in P. fimata was vice versa. Presumably, altered food quality of fungi caused compensatory responses by the collembolans, thereby diminishing the fungal signal. In a further experiment P. fimata (previously maintained with C. globosum) was kept without food for up to 4 weeks. Starvation resulted in a decline in the total amount of NLFAs; however, it did not affect the fatty acid pattern, indicating that NLFAs were degraded indiscriminately. Generally, the PLFA profile of the collembolans changed only slightly due to variations in diet quality or starvation.     

Horizontal dynamics of zooplankton in subtropical Lake Blanca (Uruguay) hosting multiple zooplankton predators and aquatic plant refuges

The Gulf of California, Mexico, consists of unique environmental conditions resulting in a rich array of biological diversity. Nematodes are present in most marine sediments and are probably the most abundant metazoans. This research analyses and compares nematode biodiversity in two shallow, littoral locations of the Gulf and compares the results with other Pacific and Atlantic faunae. Samples collected in Punta Estrella and Santa Clara were processed for nematode extraction by standard methods. A total of eighty genera were identified, sixty-seven occurring in coarser sediments at Punta Estrella and fifty-five in more silty sediments at Santa Clara. Nematode abundance was higher at the latter location, on average. The region was not especially high or low in diversity compared to other littoral sites, and was most similar to locations in Europe with a corresponding ecology but at temperate latitudes. Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users. Handling editor: K. Martens     

Effect of salinity on fungal diversity in the rhizosphere of the halophyte Avicennia germinans from a semi-arid mangrove

This study aimed to inventory fungal populations associated with the rhizosphere of Avicennia germinans in different salinity levels in a semi-arid mangrove in the Colombian tropics. Targeting the ITS1 and ITS2 regions provided complementary information, allowing a better approach to inventorying the fungal biodiversity. Amorosia and Aspergillus were the most abundant ascomycete genera, while Cystobasidium was the most abundant basidiomycete genus. Only five genera showed significant differences in abundance among the three salinity levels. Nevertheless, 65.4% of the genera were classified as exclusive for a specific salt content. Saprotrophs were the most abundant functional group and symbiotrophs were detected as mycorrhizas, fungi with biocontrol activity and entomopathogenic activity. These ecological groups play an important role in the cycling of organic matter and the availability of nutrients for mangrove plants and their tolerance to environmental and biotic stresses. This study highlights soil salinity as a determining factor in the composition of the fungal community in mangroves.     

玉米秸秆还田对土壤丛枝菌根真菌群落的影响

为揭示农业管理活动对土壤丛枝菌根(AM)真菌的影响机制,基于Illumina Miseq高通量测序平台以及脂肪酸指纹图谱方法,研究了连续4年玉米秸秆还田后,AM真菌群落组成、AM真菌生物量及其与土壤环境因子间的相互关系.结果表明:所获得的2430个AM真菌OTUs从门到种依次分类,共分为1门、3纲、4目、8科、10属、143种,但不同处理间AM真菌群落丰富度(Chao1指数和ACE指数)、多样性(Shannon、Simpson多样性指数)没有显著差异.AM真菌中类球囊霉属、球囊霉属为优势属.随秸秆还田量的增加,球囊霉属丰度降低;3000、9000 kg·hm^-2秸秆还田量下,类球囊霉属、无梗囊霉属的丰度与对照(0 kg·hm^-2)间差异达极显著水平;原囊霉属、类球囊霉属、球囊霉属在3000 kg·hm^-2秸秆还田量下与对照间差异显著,非度量多维尺度(NMDS)分析表明,9000、12000 kg·hm^-2的秸秆还田量下土壤AM真菌β多样性与对照间聚集度较其他处理相差较远,秸秆还田量对AM真菌β多样性的影响显著.多元分析结果能在累积变量82.8%上揭示土壤主要理化性状与AM真菌丰富度、多样性的空间变化关系.土壤全氮、碱解氮是影响以磷脂脂肪酸表征的土壤主要微生物类群生物量以及以中性脂肪酸表征的AM真菌生物量的主要因子.持续玉米秸秆还田改变了AM真菌属水平上的分类学组成;随秸秆还田量的增加,AM真菌特有的微生物种类减少,AM真菌群落组成间的相似度下降;秸秆还田增加了土壤AM真菌生物量及其占土壤微生物总生物量的比例.     

Evaluation of the effects of biological preparations on phytopathogenic fungi Didymella applanata and Botrytis cinerea

Fungicidal and fungistatic effects of biological preparations involving bacteria of the genera Pseudomonas and Bacillus and fungi of the genus Chaetomium on phytopathogenic fungi Didymella applanata and Botrytis cinerea were evalauated. All the biological preparations under study inhibited the growth of colonies of the fungi; however, the degree of the inhibition depended on the nature of each particular microorganism and the concentration of each particular preparation. The preparation containing Bacillus subtilis at a concentration of 0.2% effected maximum suppression of B. cinerea (the diameter of the colonies decreased sevenfold). The preparations containing bacteria of the genus Pseudomonas and fungi of the genus Chaetomium were most efficient in suppressing D. applanata. The preparations containing B. subtilis and Chaetomium spp. showed promise as agents against simultaneous development of spur blight and Botrytis blight.     

Role of meiofauna in estuarine soft-bottom habitats*

Meiofauna are ubiquitous in estuaries worldwide averaging 10⁶ m^?2. Abundance and species composition are controlled primarily by three physical factors: sediment particle size, temperature and salinity. While meiofauna are integral parts of estuarine food webs, the evidence that they are biologically controlled is equivocal. Top down (predation) control clearly does not regulate meiofaunal assemblages. Meiofauna reproduce so rapidly and are so abundant that predators cannot significantly reduce population size. Food quantity (bottom up control) also does not appear to limit meiofaunal abundance; there is little data on the effect of food quality. In estuarine sediments meiofauna: (i) facilitate biomineralization of organic matter and enhance nutrient regeneration; (ii) serve as food for a variety of higher trophic levels; and (iii) exhibit high sensitivity to anthropogenic inputs, making them excellent sentinels of estuarine pollution. Generally mineralization of organic matter is enhanced and bacterial production stimulated in the presence of meiofauna. Tannins from mangrove detritus in northern Queensland appear to inhibit meiofaunal abundance and therefore the role of meiofauna in breakdown of the leaves. Meiofauna, particularly copepods, are known foods for a variety of predators especially juvenile fish and the meiofaunal copepods are high in the essential fatty acids required by fish. The copepod’s fatty acid composition is like that of the microphytobenthos they eat; bacterial eaters (nematodes?) do not have the essential fatty acids necessary for fish. Most contaminants in estuaries reside in sediments, and meiofauna are intimately associated with sediments over their entire life-cycle, thus they are increasingly being used as pollution sentinels. Australian estuarine meiofauna research has been concentrated in Queensland, the Hunter River estuarine system in New South Wales, and Victoria’s coastal lagoons. Studies in northern Queensland have primarily concentrated on the role of nematodes in mineralization of organic matter, whereas those from southern Queensland have concentrated on the role of meiofauna as food for fish and as bacterial grazers. The New South Wales studies have concentrated on the Hunter River estuary and on the structure and function of marine nematode communities. In Victoria, several fish have been shown to eat meiofauna. The Australian world of meiofaunal research has hardly been touched; there are innumerable opportunities for meiofaunal studies. In contaminated estuarine sediments reduced trophic coupling between meiofauna and juvenile fish is a basic ecological question of habitat suitability, but also a question with relevance to management of estuarine resources. Because meiofauna have short lifecycles, the effects of a contaminant on the entire life-history can be assessed within a relatively short time. The use of modern molecular biology techniques to assess genetic diversity of meiofauna in contaminated vs uncontaminated sediments is a promising avenue for future research. Much of the important meiofaunal functions take place in very muddy substrata; thus, it is imperative to retain mudflats in estuaries.     

黑果枸杞不同组织内生真菌群落组成及生态功能分析

探究了新疆盐生植物黑果枸杞不同组织中内生真菌群落的组成及多样性,为深入研究盐碱、干旱等环境下内生真菌与宿主的互作机制,筛选和开发促生、防病和抗逆等功能的有益内生真菌资源提供科学依据。利用ITS高通量测序技术比较黑果枸杞不同组织真菌群落组成及差异,并采用FUNGuild数据库预测真菌群落生态功能。测序共获得高质量内生真菌序列354 058条,涉及291个OTUs,分属于9门、19纲、34目、50科、60属。α多样性指数分析表明,根、果中真菌群落多样性和丰富度程度较高,叶居中,花的多样性最低,茎的丰富度最低。对黑果枸杞内生真菌群落组成和优势菌群的分析表明,子囊菌门为优势菌门,花、叶、果、茎和根中相对丰度分别为86.85%、72.36%、75.97%、84.44%和85.02%。链格孢属为黑果枸杞植株中的核心属,不同组织中均有分布,在花、叶、果、茎和根中占比分别为85.41%、69.79%、47.07%、79.94%和36.97%。较优势的菌尚有枝孢属、枝顶孢属、新凸轮孢菌属、茎点霉属和楔孢黑粉菌属等真菌。这些菌多具有促生、抗逆等特性,在宿主对盐碱、干旱等极端环境的适应性方面有着潜在功能。各组织独有属的相对丰度均未超过1%。共有菌和独有菌在不同组织中的组成和相对丰度差异较大。经FUNGuild软件平台解析显示,黑果枸杞中病理-腐生-共生营养型的相对丰度最高,在花、叶、果、茎和根中分别为85.41%、69.84%、47.24%、79.98%和37.09%。果和叶中含多种相对丰度≥1%的条件致病菌,而根中腐生真菌种类较多。黑果枸杞中蕴含着功能丰富的内生真菌菌群,在不同组织中的组成及其生态功能差异较大,同时还含有大量未鉴定出种属和未定义的功能菌群,这些可为黑果枸杞功能菌群发掘提供数据参考。     

Archaea and Fungi of the Human Gut Microbiome: Correlations with Diet and Bacterial Residents

Diet influences health as a source of nutrients and toxins, and by shaping the composition of resident microbial populations. Previous studies have begun to map out associations between diet and the bacteria and viruses of the human gut microbiome. Here we investigate associations of diet with fungal and archaeal populations, taking advantage of samples from 98 well-characterized individuals. Diet was quantified using inventories scoring both long-term and recent diet, and archaea and fungi were characterized by deep sequencing of marker genes in DNA purified from stool. For fungi, we found 66 genera, with generally mutually exclusive presence of either the phyla Ascomycota or Basiodiomycota. For archaea, Methanobrevibacter was the most prevalent genus, present in 30% of samples. Several other archaeal genera were detected in lower abundance and frequency. Myriad associations were detected for fungi and archaea with diet, with each other, and with bacterial lineages. Methanobrevibacter and Candida were positively associated with diets high in carbohydrates, but negatively with diets high in amino acids, protein, and fatty acids. A previous study emphasized that bacterial population structure was associated primarily with long-term diet, but high Candida abundance was most strongly associated with the recent consumption of carbohydrates. Methobrevibacter abundance was associated with both long term and recent consumption of carbohydrates. These results confirm earlier targeted studies and provide a host of new associations to consider in modeling the effects of diet on the gut microbiome and human health.     

环境因子对乌桕内生真菌生长及脂肪酸的影响

为探讨内生菌和植物的生态关系,以生物量和脂肪酸组分作为主要指标,研究了乌桕韧皮部分离获得的5种内生真菌(丝核菌、小菌核菌、小单头孢、毛壳菌、拟盘多毛孢)在不同环境因子下的生长．与合成培养基相比,在液体马铃薯培养基上发酵,生物量较高,脂肪酸不饱和指数较低;其脂肪酸主要为棕榈酸、油酸、亚油酸．与未添加乌桕汁的合成培养基相比,添加乌桕浸汁对小菌核菌生长有促进作用,对其余4种菌有抑制作用;脂肪酸不饱和指数均进一步增加．在合成培养基中添加NaCl培养小菌核菌,生物量均无显著差异;在0～0．5mol·L^-1 NaCl时,脂肪酸不饱和指数无显著差异;在0．6～1．0mol·L^-1 NaCl时随着盐浓度增加,脂肪酸不饱和指数却下降;表明该菌有较强的耐盐能力．添加植物油对小菌核菌菌丝生长有促进作用,其中在添加1．5％的植物油时,生物量最大;其脂肪酸随添加植物油而改变．以上特点均和二者的共生关系有关．     

Carbon assimilating fungi from surface ocean to subseafloor revealed by coupled phylogenetic and stable isotope analysis

Fungi are ubiquitous in the ocean and hypothesized to be important members of marine ecosystems, but their roles in the marine carbon cycle are poorly understood. Here, we use ¹³C DNA stable isotope probing coupled with phylogenetic analyses to investigate carbon assimilation within diverse communities of planktonic and benthic fungi in the Benguela Upwelling System (Namibia). Across the redox stratified water column and in the underlying sediments, assimilation of ¹³C-labeled carbon from diatom extracellular polymeric substances (¹³C-dEPS) by fungi correlated with the expression of fungal genes encoding carbohydrate-active enzymes. Phylogenetic analysis of genes from ¹³C-labeled metagenomes revealed saprotrophic lineages related to the facultative yeast Malassezia were the main fungal foragers of pelagic dEPS. In contrast, fungi living in the underlying sulfidic sediments assimilated more ¹³C-labeled carbon from chemosynthetic bacteria compared to dEPS. This coincided with a unique seafloor fungal community and dissolved organic matter composition compared to the water column, and a 100-fold increased fungal abundance within the subseafloor sulfide-nitrate transition zone. The subseafloor fungi feeding on ¹³C-labeled chemolithoautotrophs under anoxic conditions were affiliated with Chytridiomycota and Mucoromycota that encode cellulolytic and proteolytic enzymes, revealing polysaccharide and protein-degrading fungi that can anaerobically decompose chemosynthetic necromass. These subseafloor fungi, therefore, appear to be specialized in organic matter that is produced in the sediments. Our findings reveal that the phylogenetic diversity of fungi across redox stratified marine ecosystems translates into functionally relevant mechanisms helping to structure carbon flow from primary producers in marine microbiomes from the surface ocean to the subseafloor.Subject terms: Microbial ecology, Fungal ecology, Microbiome, Biogeochemistry