Differences in composition of small,motile invertebrate assemblages from seagrass and unvegetated habitats in a southern Australian estuary

Assemblages of small, motile invertebrates (epifauna) from eelgrass(Zostera muelleri) and unvegetated habitats in a shallow, marine-dominatedestuary were compared at five sampling periods over one year. Assemblagesbased on abundance and biomass of 21 taxa from the two habitats groupedseparately in multivariate analyses (MDS ordination), and these groupingswere shown to be significant using an analysis of similarities (ANOSIM)randomisation routine. Secondarily to habitat differences, weak influencesof water temperature and distance to open water, but not of salinity, weredetected at some periods. Abundance and biomass of key taxa and all speciescombined were higha in eelgrass than in unvegetated habitat. Cumaceans wereexceptional in being collected predominantly from unvegetated habitat. Totalepifaunal production and crustacean production estimated using twovariables, (1) the biomass of individuals of each size class, and (2) watertemperature, were also higher in eelgrass than in unvegetated habitat. Thehigher abundance in eelgrass of taxa such as amphipods, harpacticoidcopepods and polychaetes that are major components of the diets of smallfish is consistent with a model explaining higher fish numbers in eelgrassin terms of prey availability.     

Experimental sensitivity analysis of a trickle bed bioreactor for lignin peroxidases production by P. chrysosporium

A systematic experimental analysis of the parameters affecting the behaviour of a Trickle Bed Reactor (TBR) was performed. Lignin peroxidases (LiPs) were produced in the reactor by Phanerochaete chrysosporium entrapped in a Ca-alginate film covering ceramic supports (Berl saddles). Gas and liquid velocity, liquid flow regime, and thickness of encapsulating matrix were experimentally investigated. Reactor productivity and biological activity were considered as representative of reactor performance and evaluated by six probe parameters to take into account different process system configurations, i.e. single LiP extraction, multiple LiP extraction every 24 h and in vivo applications. Liquid fluid dynamics were the critical phenomena affecting LiPs production; the ranges of gas and liquid superficial velocity influencing the reactor performance were also identified. Alginate film thickness was shown to influence specific biomass activity but a limited impact on reactor productivity was verified.     

Efficient preparation of enantiopure l-tert-leucine through immobilized penicillin G acylase catalyzed kinetic resolution in aqueous medium

Racemic _DL-tert-leucine (_DL-Tle) was resolved to obtain enantiopure _L-Tle through enantioselective hydrolysis of its N-phenylacetyl derivative with immobilized penicillin G acylase (PGA). The effects of pH, reaction temperature, substrate concentration and reaction time on the reaction were investigated. The reaction was conveniently carried out at 0.4 M substrate concentration in water at pH 8.0 and 30 °C. Under the optimized reaction conditions, _L-Tle was obtained in an enantiopure form (>99% ee) with 45.8% substrate conversion after 4 h. The thermal stability and operational stability of immobilized PGA were examined. Furthermore, the preparation of _L-Tle was successfully performed in a recirculating packed bed reactor (RPBR) system and immobilized PGA exhibited a long-term stability for 51 days with a slight decrease of activity. The isolated _D-enantiomer was racemized at 160 °C for 15 min and reused as substrate. The results obtained clearly demonstrated a potential for industrial application of immobilized PGA in the preparation of _L-Tle through enantioselective hydrolysis of its N-phenylacetyl derivative.     

Biodegradation of phenol and chlorophenols with defined mixed culture in shake-flasks and a packed bed reactor

Pseudomonas testosteroni CPW301 degraded phenol and 4-chlorophenol simultaneously, but degradation rates of these compounds were affected by 4-chlorophenol. Phenol increased the cell concentration and therefore the degradation efficiency of 4-chlorophenol was improved. Pseudomonas solanacearum TCP114 could degrade only 2,4,6-trichlorophenol. A defined mixed culture of P. testosteroni CPW301 and P. solanacearum TCP114 could treat phenol, 4-chlorophenol, and 2,4,6-trichlorophenol completely and overcome the inhibition of substrates to other microorganisms. The degradation capacity of the packed bed reactor (PBR) was higher than that of the continuous stirred tank reactor, but the PBR was unsuitable for oxygen-sensitive microorganisms.     

Factors delimiting the boundary between vertically contiguous mussel beds ofSeptifer virgatus (Wiegmann) andHormomya mutabilis (Gould)

On moderately wave-exposed rocky shores in middle Japan, the upper interidal mytilid,Septifer virgatus, and lower intertidal mytilid,Hormomya mutabilis, occur together, forming vertically contiguous mussed beds. Factors limiting the lower distribution limit ofSeptifer and the upper limit ofHormomya were investigated by collections of natural mussel clumps and single- and mixed-species transplantation experiments. Newly settled juvenileSeptifer (<5 mm shell length) were significantly fewer in the natural and artificialHormomya clumps than in theSeptifer clumps. Both natural and artificialHormomya clumps accumulated a much greater amount of sediment than did theSeptifer clumps.Hormomya clumps inhibited the recruitment ofSeptifer, presumably through accumulation of sediment, which resulted in setting the lower limit of theSeptifer zone. Survivorship of small (5–10 mm) and large (>15 mm)Hormomya was much lower inHormomya clumps transplanted upwards into theSeptifer zone than it was inHormomya clumps in theHormomya zone. In mixed-species clumps in theSeptifer zone, however, survivorship of smallHormomya was not significantly different from that in mixed-species clumps in theHormomya zone.Septifer had a positive effect on the survival of smallHormomya and increased the upper limit ofHormomya, presumably by providing shelter and thus protecting them from desiccation. The upper limit ofHormomya zone was thus considered to be set by desiccation exceeding the physiological tolerance of the species.     

Inert filter media for the biofiltration of waste gases – characteristics and biomass control

Soil biofilters and related systems based onthe use of natural filter beds have been usedfor several years for solving specific airpollution problems. Over the past decade,significant improvements have been brought tothese original bioprocesses, among which thedevelopment and use of new inert packingmaterials. The present paper overviews the mostcommon inert packings used in biofiltration ofwaste gases and their major characteristics. Apotential problem recently encountered whenusing inert filter beds is the heterogenousdistribution of biomass on the packingmaterial, and the excessive growth andaccumulation of biomass when treating highorganic loads, eventually leading to cloggingof the biofilter and reduced efficiency.Several strategies that have been proposed forsolving such problems are described in thispaper. Technologies for controlling excessbiomass accumulation can be grouped into fourcategories based on the use of mechanicalforces, the use of specific chemicals, thereduction of microbial growth, and predation.