Variations in bacterial decay between cell types and between cell wall regions in waterlogged archaeological wood excavated in the intertidal zone

The bacterial decay of waterlogged archeological wood (WAW, hard pine spp.) taken from Daebudo shipwreck No. 2, which was buried in the intertidal zone in the mid-west coast (Yellow sea) of South Korea approximately 800 years ago, was investigated. The maximum moisture content of the outer parts (approx. 3 cm of depth) of WAW was approximately 4.2 times higher than that of undegraded reference pine wood. ATR-FTIR and solid-state 13C-NMR analysis indicated a relative increase of the lignin concentration in WAW caused by the degradation of cellulose and hemicelluloses across the board studied (31-cm-wide and 14.5-cm-thick board). Micromorphological studies also revealed that bacterial degradation was progressed to a depth of 15 cm (vertically 7.3 cm) from the surface, which is the innermost part of the board. Erosion bacteria (EB) were identified as the main degraders of WAW. Degradation by tunneling bacteria (TB) was occasionally detected. Decay resistance to bacterial attacks in WAW varied between cell types and between cell wall regions. Axial tracheids showed less resistance than ray tracheids, ray parenchyma cells, and axial intercellular canal cells, including strand tracheids, subsidiary parenchyma cells, and epithelial cells. Decay resistance was higher in ray tracheids and strand tracheids than in ray parenchyma cells and subsidiary parenchyma-/epithelial cells, respectively. Bordered- and cross-field pit membranes and the initial pit borders showed higher decay resistance than the tracheid cell walls. Overall, the S2 layer of the axial tracheids showed the weakest resistance to bacterial attacks.

Postharvest storage.

Successful postharvest storage of horticultural produce is a vital aspect of feeding the world's population and has been so for as long as crops have been cultivated. Many fruit, nut, grain, vegetable, cut flower and ornamental crops deteriorate rapidly postharvest unless specific treatments, curing, drying or temperatures are maintained to slow the rate of respiration and reduce the occurrence of fungal and bacterial decay. Postharvest storage aims to preserve the desirable characteristics and nutritional quality of produce for as long as is required before consumption. Along with this, food safety during storage is a major consideration as is consumer perception of appearance, taste and increasingly these days, convenience and nutrition.

Correlation between bacterial decay and chemical changes in waterlogged archaeological wood analysed by light microscopy and Py-GC/MS

Erosion bacteria are the main degraders of archaeological wood excavated from waterlogged environments. Light microscopy and analytical pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS) were exploited to study waterlogged archaeological wood (Pinus sylvestris L.) at different stages of bacterial decay. The research explored the biochemical changes related to erosion bacteria degradation of the secondary cell wall in the wood cells and the chemical changes related to abiotic processes induced by the long-term waterlogged burial environment. Erosion bacteria were demonstrated by chemical analysis to cause significant holocellulose depletion. Detailed analysis of the holocellulose and lignin pyrolysis products revealed only minor chemical changes in the residual structure even after heavy erosion bacteria decay. Chemical changes in the lignin polymer is associated to enzymatic unlocking of the lignocellulose to gain access to the holocellulose fraction of the cell wall. Chemical changes in the holocellulose fraction are suggested to stem from depolymerisation and from alterations in the polymer matrix of the residual wood cell wall structure. Interestingly, a difference was observed between the sound reference wood and the waterlogged archaeological wood without erosion bacteria decay, indicating that long-term exposure in waterlogged environments results in partial decay of the holocellulose even in absence of bacterial activity.

Immobilization of Phosphatidylserine by Ethanol and Lysozyme on the Cell Surface for Evaluation of Apoptosis-Like Decay in Activated-Sludge Bacteria

ABSTRACT Accurate determination of microbial viability can be crucial in microbe-dominated biosystems. However, the identification of metabolic decay in bacterial cells can be elaborate and difficult. We sought to identify apoptosis-like bacterial processes by using annexin V-fluorescein isothiocyanate (FITC) (AVF), a probe typically used to stain phosphatidylserine (PS) on exposed cell membranes. The bacterial cell wall provides a barrier that is responsible for low efficiency of direct PS staining of decayed bacterial cells. This can be overcome by pretreatment of the bacteria with 70% ethanol, which fixates the bacteria and preserves the PS status, combined with lysozyme treatment to hydrolyze the cell wall. That treatment improved the efficiency of AVF staining considerably, as shown for pure strains of an Ochrobactrum sp. and a Micrococcus sp. Using this method, decayed bacterial cells (induced by starvation) were more strongly stained, indicating externalization of PS to a greater extent than seen for cells harvested at logarithmic growth. A multispecies microbial sludge was artificially decayed by heat treatment or alternating anoxic-oxic treatment, which also induced increased AVF staining, again presumably via decay-related PS externalization. The method developed proved to be efficient for identification of bacterial decay and has potential for the evaluation of multispecies bacterial samples from sources like soil matrix, bioaerosol, and activated sludge. IMPORTANCE Since the externalization of phosphatidylserine (PS) is considered a crucial characteristic of apoptosis, we sought to identify apoptosis-like decay in bacterial cells by PS staining using AVF. We show that this is possible, provided the bacteria are pretreated with ethanol plus lysozyme to remove a physical staining barrier and preserve the original, decay-related externalization of PS. Our work suggests that PS externalization occurs in starved bacteria and this can be quantified with AVF staining, providing a measure of bacterial decay. Since PS is the common component of the lipid bilayer in bacterial cell membranes, this approach also has potential for evaluation of cell decay of other bacterial species.

The use of fish dryer to improve the quality of dry salted anchovy (Stolephorus heterolobus) during storage

Title (Bahasa Indonesia): Penggunaan alat pengering ikan untuk meningkatkan mutu ikan teri (Stolephorus heterolobus) asin kering selama penyimpanan Dried salted fish processing, in general, is still traditional, since it is drying directly without using a dryer so that the resulting product can be easily damaged and quickly contaminated by bacterial decay. The use of fish dryers to be one solution in addressing the problems in the processing of fishery products such as dried salted fish. The purpose of this study was to look at the benefits of using fish dryers to the quality of dried salted fish products from various storing methods. Results showed that during 1, 2, and 3 months storage of dryer-based salted fish, total TPC and total fungi were still in the quality standards condition and below the threshold. Panelist’s assessment reflected that organoleptic appearance, odor, flavor, and consistency of the dryer-based salted fish products still met standards established by National Standard of Indonesia. Jenis usaha pengolahan ikan asin kering, pada umumnya, masih bersifat tradisional melalui penjemuran langsung tanpa menggunakan alat pengering sehingga produk, yang dihasilkan, mudah rusak dan cepat terkontaminasi oleh bakteri pembusuk. Tujuan penelitian ini adalah untuk melihat manfaat penggunaan alat pengering ikan (tipe bongkar pasang) terhadap nilai mutu dari produk ikan teri asin kering, yang dihasilkan dengan berbagai metode penyimpanan. Hasil penelitian menunjukkan bahwa total TPC dan total kapang ikan teri asin kering, yang dikeringkan menggunakan alat pengering, masih sesuai dengan standar mutu dan jauh dari ambang batas. Hasil penilaian panelis terhadap nilai organoleptik kenampakan, bau, rasa, dan konsistensi pada produk ikan teri asin kering, yang dikeringkan dengan menggunakan alat pengering, secara keseluruhan, masih sesuai dengan standar mutu organoleptik yang ditetapkan oleh Standar Nasional Indonesia (SNI).