No abstract

Auricularia polytricha was cultivated on a sawdust basal substrate supplemented with different proportions (30%, 45%, and 60%, respectively) of stalks of three grass plants, i.e., Panicum repens (PRS), Pennisetum purpureum (PPS), and Zea mays (ZMS), to determine the most effective substrate. The mycelial growth rate, total colonization time, days to primordial formation, biological efficiency and chemical composition of fruiting bodies were evaluated. The results indicated that 30PPS was the best substrate for mycelial growth of A. polytricha , with a corresponding total colonization period of 32.0 days. With the exception of 30PPS, the total biological efficiency of all of the substrates containing P. repens stalk, P. purpureum stalk and Z. mays stalk was higher ( P < 0.05) than that of the control. The most suitable substrate with a high biological efficiency was 60PRS (148.12%), followed by 30ZMS (145.05%), 45ZMS (144.15%) and 30PRS (136.68%). The nutrient values of fruiting bodies were affected by different substrates. The ash contents of A. polytricha cultivated on a substrate containing Z. mays stalk were higher than that of the control; meanwhile, the protein contents of mushroom cultivated on a substrate containing P. repens stalk (except substrate 45PRS) were higher than that of the control. The biological efficiency of the substrates was tested, and according to the results, it is feasible to use the stalks of P. repens and Z. mays on partially replaced sawdust to cultivate A. polytricha .

Most plant-produced monoterpenes can be degraded by soil microorganisms. Borneol is a plant terpene that is widely used in traditional Chinese medicine. Neither microbial borneol dehydrogenase (BDH) nor a microbial borneol degradation pathway has been reported previously. One borneol-degrading strain, Pseudomonas sp. strain TCU-HL1, was isolated by our group. IMPORTANCEThe degradation of borneol in a soil microorganism through a camphor degradation pathway is reported in this study. We also report a microbial borneol dehydrogenase. The k cat and k cat /K m values of lavender BDH are about 1,800-fold and 500-fold lower, respectively, than those of TCU-HL1 BDH. The indigenous borneol-and camphor-degrading strain isolated, Pseudomonas sp. strain TCU-HL1, reminds us of the time 100 years ago when Taiwan was the major producer of natural camphor in the world.

The cause of fruit cracking can be diverse and the reasons vary among species. Wax apple (Syzygium samarangense) fruit is an economically valuable fruit in Southeast Asia and in Taiwan. The main problem in the production of wax apple is cracking which reduces its market value. The aim of this study is to identify the factors associated with fruit cracking in wax apple. Results showed that the contents of total soluble sugars and total titratable acid were both 20% higher in cracked fruits than in uncracked fruits, and the osmotic potential was 40% lower; water potential was similar; turgor pressure was 60% higher, and specific activity of polygalacturonase was 131% higher. Based on the above results, the physiological factors for fruit cracking in wax apple are hypothesized.The increase in total soluble sugars and total titratable acid during fruit maturation leads to decreased tissue osmotic potential. Water absorption in response to this decrease in osmotic potential can cause cells to swell, which increase the turgor pressure resulting in rupture of the cells and tissues. The increase in polygalacturonase activity weakens the cell walls. Those combined factors result in fruit cracking.

Rhinogobius gigas is an amphidromous fish endemic to eastern Taiwan. Fishes with the diadromous behavior are expected to have a broader distribution range and higher genetic homogeneity despite that some amphidromous fishes with limited distribution are observed and R. gigas is an additional exception with a limited distribution range. Rhinogobius gigas has been documented to be retained inshore near the river plume with a short pelagic larval duration of 30–40 days, which may account for the endemism of this species. The short marine larval stage of R. gigas may imply a population genetic structure and the aim of the present study is to test whether the population genetic structure is present in R. gigas. To test the population genetic structure, fragments of mitochondrial displacement loop and cytochrome c oxidase subunit I were sequenced to provide molecular inference for genetic structure among populations. Sixty-nine haplotypes were identified among 191 R. gigas from 10 populations of eastern Taiwan and the mean haplotype and nucleotide diversities for all samples were 0.956 and 0.0024, respectively, implying a bottleneck followed by a recent population expansion further supported by Fu’s Fs (-26.6; p < 0.001) and Tajima’s D (-1.5; p = 0.037) values. The phylogenetic analysis revealed lack of genetic structure and the bush-like median joining network without commonly shared haplotypes supports the same scenario. The genetic homogeneity is probably due to the amphidromous life history providing the opportunity for passive larval transportation among the rivers through coastal currents in eastern Taiwan. The endemism to eastern Taiwan may be a consequence of complicated interactions among short pelagic larval duration, interspecific competition and coastal currents.